混凝土桥梁裂缝中英文对照外文翻译文献
外文翻译完整版CORROSION AND PRESTRESSED CONCRETE BRIDGES
CORROSION AND PRESTRESSED CONCRETE BRIDGESAdrian T.Ciolko,P.E.1腐蚀和预应力混凝土桥梁阿德里安· T.Ciolko P.E.1AbstractThe impact on bridge reliability,of prestressing steel deterioration and tendonrupture created by corrosion mechanisms,is much more critical and rapid thanthat of any other component of a prestressed concrete bridge.Additionally,deterioration of embedded prestressing reinforcement in these structures may notnecessarily be made visible through manifestation of external distress in theConcrete.摘要腐蚀机制引起预应力钢筋的恶化和断裂，进而对桥梁的可靠性产生影响，这比对预应力混凝土桥的其他部分的影响更加严重，也更加迅速。
此外，在这些结构中，有粘结预应力钢筋的恶化也不必要通过混凝土外部糟糕的状况表现出来。
Initiating mechanisms and particular forms of corrosion affectingprestressed concrete structures are described based on the author’s experience.These degradation mechanisms include:•Chlorides and Corrosion•Concrete Carbonation Effects•Influence of Concrete Cracking•Electrochemical (Macrocell) and Pitting Corrosion•Stress Corrosion Cracking and Steel Embrittlement•Fretting Corrosion•Corrosion and Fatigue关于腐蚀影响预应力混凝土结构的最初机制和特定形式的描述是基于作者的经验。
桥梁工程外文翻译---桥梁裂缝产生原因浅析
The bridge crack produced the reason to simply analyseIn recent years, the traffic capital construction of our province gets swift and violent development, all parts have built a large number of concrete bridges. In the course of building and using in the bridge, relevant to influence project quality lead of common occurrence report that bridge collapse even because the crack appears The concrete can be said to " often have illness coming on " while fracturing and " frequently-occurring disease ", often perplex bridge engineers and technicians. In fact , if take certain design and construction measure, a lot of cracks can be overcome and controlled. For strengthen understanding of concrete bridge crack further, is it prevent project from endanger larger crack to try one's best, this text make an more overall analysis , summary to concrete kind and reason of production , bridge of crack as much as possible, in order to design , construct and find out the feasible method which control the crack , get the result of taking precautions against Yu WeiRan.Concrete bridge crack kind, origin cause of formation In fact, the origin cause of formation of the concrete structure crack is complicated and various, even many kinds of factors influence each other , but every crack has its one or several kinds of main reasons produced . The kind of the concrete bridge crack, on its reason to produce, can roughly divide several kinds as follows :(1) load the crack caused Concrete in routine quiet .Is it load to move and crack that produce claim to load the crack under the times of stress bridge, summing up has direct stress cracks , two kinds stress crack onces mainly. Direct stress crack refer to outside load direct crack that stress produce that cause. The reason why the crack produces is as follows, 1, Design the stage of calculating , does not calculate or leaks and calculates partly while calculating in structure; Calculate the model is unreasonable; The structure is supposed and accorded with by strength actually by strength ; Load and calculate or leak and calculate few; Internal force and matching the mistake in computation of muscle; Safety coefficient of structure is not enough. Do not consider the possibility that construct at the time of the structural design; It is insufficient to design the section; It is simply little and assigning the mistake for reinforcing bar to setup; Structure rigidity is insufficient; Construct and deal with improperly; The design drawing can not be explained clearly etc.. 2, Construction stage, does not pile up and construct the machines , material limiting ; Is it prefabricate structure structure receive strength characteristic , stand up , is it hang , transport , install to get up at will to understand; Construct not according to the design drawing, alter the construction order of the structure without authorization , change the structure and receive the strength mode; Do not do the tired intensity checking computations under machine vibration and wait to the structure . 3, Using stage, the heavy-duty vehicle which goes beyond the design load passes the bridge; Receive the contact , striking of the vehicle , shipping; Strong wind , heavy snow , earthquake happen , explode etc.. Stress crack once means the stress of secondary caused by loading outside produces the crack. The reason why the crack produces is as follows, 1, In design outside load function , because actual working state and routine , structure of thing calculate have discrepancy or is it consider to calculate, thus cause stress once to cause the structure to fracture in some position. Two is it join bridge arch foot is it is it assign " X " shape reinforcing bar , cut down this place way , section of size design and cut with scissors at the same time to adopt often to design to cut with scissors, theory calculate place this can store curved square in , but reality should is it can resist curved still to cut with scissors, so that present the crack and cause the reinforcing bar corrosion. 2, Bridge structure is it dig trough , turn on hole , set up ox leg ,etc. to need often, difficult to use a accurate one diagrammatic to is it is it calculate to imitate to go on in calculating in routine, set up and receive the strength reinforcing bar in general foundation experience. Studies have shown , after being dug the hole by the strength component , it will produce the diffraction phenomenon that strength flows, intensive near the hole in a utensil, produced the enormous stress to concentrate. In long to step prestressing force of the continuous roof beam , often block the steel bunch according to the needs of section internal force in stepping, set up the anchor head, but can often see the crack in the anchor firm section adjacent place. So if deal with improper, in corner or component form sudden change office , block place to be easy to appear crack strength reinforcing bar of structure the. In the actual project, stress crack once produced the mostcommon reason which loads the crack. Stress crack once belong to one more piece of nature of drawing , splitting off , shearing. Stress crack once is loaded and caused, only seldom calculate according to the routine too, but with modern to calculate constant perfection of means, times of stress crack to can accomplish reasonable checking computations too. For example to such stresses 2 times of producing as prestressing force , creeping ,etc., department's finite element procedure calculates levels pole correctly now, but more difficult 40 years ago. In the design, should pay attention to avoiding structure sudden change (or section sudden change), when it is unable to avoid , should do part deal with , corner for instance, make round horn , sudden change office make into the gradation zone transition, is it is it mix muscle to construct to strengthen at the same time, corner mix again oblique to reinforcing bar , as to large hole in a utensil can set up protecting in the perimeter at the terms of having angle steel. Load the crack characteristic in accordance with loading differently and presenting different characteristics differently. The crack appear person who draw more, the cutting area or the serious position of vibration. Must point out , is it get up cover or have along keep into short crack of direction to appear person who press, often the structure reaches the sign of bearing the weight of strength limit, it is an omen that the structure is destroyed, its reason is often that sectional size is partial and small. Receive the strength way differently according to the structure, the crack characteristic produced is as follows: 1, The centre is drawn. The crack runs through the component cross section , the interval is equal on the whole , and is perpendicular to receiving the strength direction. While adopting the whorl reinforcing bar , lie in the second-class crack near the reinforcing bar between the cracks. 2, The centre is pressed. It is parallel on the short and dense parallel crack which receive the strength direction to appear along the component. 3, Receive curved. Most near the large section from border is it appear and draw into direction vertical crack to begin person who draw curved square, and develop toward neutralization axle gradually. While adopting the whorl reinforcing bar , can see shorter second-class crack among the cracks. When the structure matches muscles less, there are few but wide cracks, fragility destruction may take place in the structure 4, Pressed big and partial. Heavy to press and mix person who draw muscle a lessone light to pigeonhole into the component while being partial while being partial, similar to receiving the curved component. 5, Pressed small and partial. Small to press and mix person who draw muscle a more one heavy to pigeonhole into the component while being partial while being partial, similar to the centre and pressed the component. 6, Cut. Press obliquly when the hoop muscle is too dense and destroy, the oblique crack which is greater than 45?? direction appears along the belly of roof beam end; Is it is it is it destroy to press to cut to happen when the hoop muscle is proper, underpart is it invite 45?? direction parallel oblique crack each other to appear along roof beam end. 7, Sprained. Component one side belly appear many direction oblique crack, 45?? of treaty, first, and to launch with spiral direction being adjoint. 8, Washed and cut. 4 side is it invite 45?? direction inclined plane draw and split to take place along column cap board, form the tangent plane of washing. 9, Some and is pressed. Some to appear person who press direction roughly parallel large short cracks with pressure.(2) crack caused in temperature changeThe concrete has nature of expanding with heat and contract with cold, look on as the external environment condition or the structure temperature changes, concrete take place out of shape, if out of shape to restrain from, produce the stress in the structure, produce the temperature crack promptly when exceeding concrete tensile strength in stress. In some being heavy to step foot-path among the bridge , temperature stress can is it go beyond living year stress even to reach. The temperature crack distinguishes the main characteristic of other cracks will be varied with temperature and expanded or closed up. The main factor is as follows, to cause temperature and change 1, Annual difference in temperature. Temperature is changing constantly in four seasons in one year, but change relatively slowly, the impact on structure of the bridge is mainly the vertical displacement which causes the bridge, can prop up seat move or set up flexible mound ,etc. not to construct measure coordinate , through bridge floor expansion joint generally, can cause temperature crack only when the displacement of the structure is limited, for example arched bridge , just bridge etc. The annual difference in temperature of our country generally changes the range with the conduct of the average temperature in the moon of January and July.Considering the creep characteristic of the concrete, the elastic mould amount of concrete should be considered rolling over and reducing when the internal force of the annual difference in temperature is calculated. 2, Rizhao. After being tanned by the sun by the sun to the side of bridge panel , the girder or the pier, temperature is obviously higher than other position, the temperature gradient is presented and distributed by the line shape . Because of restrain oneself function, cause part draw stress to be relatively heavy, the crack appears. Rizhao and following to is it cause structure common reason most , temperature of crack to lower the temperature suddenly 3, Lower the temperature suddenly. Fall heavy rain , cold air attack , sunset ,etc. can cause structure surface temperature suddenly dropped suddenly, but because inside temperature change relatively slow producing temperature gradient. Rizhao and lower the temperature internal force can adopt design specification or consult real bridge materials go on when calculating suddenly, concrete elastic mould amount does not consider converting into and reducing 4, Heat of hydration. Appear in the course of constructing, the large volume concrete (thickness exceeds 2. 0), after building because cement water send out heat, cause inside very much high temperature, the internal and external difference in temperature is too large, cause the surface to appear in the crack. Should according to actual conditions in constructing, is it choose heat of hydration low cement variety to try one's best, limit cement unit's consumption, reduce the aggregate and enter the temperature of the mould , reduce the internal and external difference in temperature, and lower the temperature slowly , can adopt the circulation cooling system to carry on the inside to dispel the heat in case of necessity, or adopt the thin layer and build it in succession in order to accelerate dispelling the heat. 5, The construction measure is improper at the time of steam maintenance or the winter construction , the concrete is sudden and cold and sudden and hot, internal and external temperature is uneven , apt to appear in the crack. 6, Prefabricate T roof beam horizontal baffle when the installation , prop up seat bury stencil plate with transfer flat stencil plate when welding in advance, if weld measure to be improper, iron pieces of nearby concrete easy to is it fracture to burn. Adopt electric heat piece draw law piece draw prestressing force at the component , prestressing force steel temperature can rise to 350 degrees Centigrade , the concretecomponent is apt to fracture. Experimental study indicates , are caused the intensity of concrete that the high temperature burns to obviously reduce with rising of temperature by such reasons as the fire ,etc., glueing forming the decline thereupon of strength of reinforcing bar and concrete, tensile strength drop by 50% after concrete temperature reaches 300 degrees Centigrade, compression strength drops by 60%, glueing the strength of forming to drop by 80% of only round reinforcing bar and concrete; Because heat, concrete body dissociate ink evaporate and can produce and shrink sharply in a large amount(3) shrink the crack causedIn the actual project, it is the most common because concrete shrinks the crack caused. Shrink kind in concrete, plasticity shrink is it it shrinks (is it contract to do ) to be the main reason that the volume of concrete out of shape happens to shrink, shrink spontaneously in addition and the char shrink. Plasticity shrink. About 4 hours after it is built that in the course of constructing , concrete happens, the cement water response is fierce at this moment, the strand takes shape gradually, secrete water and moisture to evaporate sharply, the concrete desiccates and shrinks, it is at the same time conduct oneself with dignity not sinking because aggregate,so when harden concrete yet,it call plasticity shrink. The plasticity shrink producing amount grade is very big, can be up to about 1%. If stopped by the reinforcing bar while the aggregate sinks, form the crack along the reinforcing bar direction. If web , roof beam of T and roof beam of case and carry baseplate hand over office in component vertical to become sectional place, because sink too really to superficial obeying the web direction crack will happen evenly before hardenning. For reducing concrete plasticity shrink,it should control by water dust when being construct than,last long-time mixing, unloading should not too quick, is it is it take closely knit to smash to shake, vertical to become sectional place should divide layer build. Shrink and shrink (do and contract). After the concrete is formed hard , as the top layer moisture is evaporated progressively , the humidity is reduced progressively , the volume of concrete is reduced, is called and shrunk to shrink (do and contract). Because concrete top layer moisture loss soon, it is slow for inside to lose, produce surface shrink heavy , insideshrink a light one even to shrink, it is out of shape to restrain from by the inside concrete for surface to shrink, cause the surface concrete to bear pulling force, when the surface concrete bears pulling force to exceed its tensile strength, produce and shrink the crack. The concrete hardens after-contraction to just shrink and shrink mainly .Such as mix muscle rate heavy component (exceed 3% ), between reinforcing bar and more obvious restraints relatively that concrete shrink, the concrete surface is apt to appear in the full of cracks crackle. Shrink spontaneously. Spontaneous to it shrinks to be concrete in the course of hardenning , cement and water take place ink react, the shrink with have nothing to do by external humidity, and can positive (whether shrink, such as ordinary portland cement concrete), can negative too (whether expand, such as concrete, concrete of slag cement and cement of fly ash). The char shrinks. Between carbon dioxide and hyrate of cement of atmosphere take place out of shape shrink that chemical reaction cause. The char shrinks and could happen only about 50% of humidity, and accelerate with increase of the density of the carbon dioxide. The char shrinks and seldom calculates . The characteristic that the concrete shrinks the crack is that the majority belongs to the surface crack, the crack is relatively detailed in width , and criss-cross, become the full of cracks form , the form does not have any law . Studies have shown , influence concrete shrink main factor of crack as follows, 1, Variety of cement , grade and consumption. Slag cement , quick-hardening cement , low-heat cement concrete contractivity are relatively high, ordinary cement , volcanic ash cement , alumina cement concrete contractivity are relatively low. Cement grade low in addition, unit volume consumption heavy rubing detailed degree heavy, then the concrete shrinks the more greatly, and shrink time is the longer. For example, in order to improve the intensity of the concrete , often adopt and increase the cement consumption method by force while constructing, the result shrinks the stress to obviously strengthen . 2, Variety of aggregate. Such absorbing water rates as the quartz , limestone , cloud rock , granite , feldspar ,etc. are smaller, contractivity is relatively low in the aggregate; And such absorbing water rates as the sandstone , slate , angle amphibolite ,etc. are greater, contractivity is relatively high. Aggregate grains of foot-path heavy to shrink light in addition, water content big to shrink the larger. 3, Water gray than. The heavier waterconsumption is, the higher water and dust are, the concrete shrinks the more greatly. 4, Mix the pharmaceutical outside. It is the better to mix pharmaceutical water-retaining property outside, then the concrete shrinks the smaller. 5, Maintain the method . Water that good maintenance can accelerate the concrete reacts, obtain the intensity of higher concrete. Keep humidity high , low maintaining time to be the longer temperature when maintaining, then the concrete shrinks the smaller. Steam maintain way than maintain way concrete is it take light to shrink naturall. 6, External environment. The humidity is little, the air drying , temperature are high, the wind speed is large in the atmosphere, then the concrete moisture is evaporated fast, the concrete shrinks the faster. 7, Shake and smash the way and time. Machinery shake way of smashing than make firm by ramming or tamping way concrete contractivity take little by hand. Shaking should determine according to mechanical performance to smash time , are generally suitable for 55s / time. It is too short, shake and can not smash closely knit , it is insufficient or not even in intensity to form the concrete; It is too long, cause and divide storey, thick aggregate sinks to the ground floor, the upper strata that the detailed aggregate stays, the intensity is not even , the upper strata incident shrink the crack. And shrink the crack caused to temperature, worthy of constructing the reinforcing bar againing can obviously improve the resisting the splitting of concrete , structure of especially thin wall (thick 200cm of wall ). Mix muscle should is it adopt light diameter reinforcing bar (8 |? construct 14 |? ) to have priority , little interval assign (whether @ 10 construct @ 15cm ) on constructing, the whole section is it mix muscle to be rate unsuitable to be lower than 0 to construct. 3%, can generally adopt 0 . 3%~0. 5%.(4), crack that causes out of shape of plinth of the groundBecause foundation vertical to even to subside or horizontal direction displacement, make the structure produce the additional stress, go beyond resisting the ability of drawing of concrete structure, cause the structure to fracture. The even main reason that subside of the foundation is as follows, 1, Reconnoitres the precision and is not enough for , test the materials inaccuratly in geology. Designing, constructing without fully grasping the geological situation, this is the main reason that cause the ground not to subside evenly . Such as hills area or bridge, district of mountain ridge,, hole interval to be too far whenreconnoitring, and ground rise and fall big the rock, reconnoitring the report can't fully reflect the real geological situation . 2, The geological difference of the ground is too large. Building it in the bridge of the valley of the ditch of mountain area, geology of the stream place and place on the hillside change larger, even there are weak grounds in the stream, because the soil of the ground does not causes and does not subside evenly with the compressing. 3, The structure loads the difference too big. Under the unanimous terms, when every foundation too heavy to load difference in geological situation, may cause evenly to subside, for example high to fill out soil case shape in the middle part of the culvert than to is it take heavy to load both sides, to subside soon heavy than both sides middle part, case is it might fracture to contain 4, The difference of basic type of structure is great. Unite it in the bridge the samly , mix and use and does not expand the foundation and a foundation with the foundation, or adopt a foundation when a foot-path or a long difference is great at the same time , or adopt the foundation of expanding when basis elevation is widely different at the same time , may cause the ground not to subside evenly too 5, Foundation built by stages. In the newly-built bridge near the foundation of original bridge, if the half a bridge about expressway built by stages, the newly-built bridge loads or the foundation causes the soil of the ground to consolidate again while dealing with, may cause and subside the foundation of original bridge greatly 6, The ground is frozen bloatedly. The ground soil of higher moisture content on terms that lower than zero degree expands because of being icy; Once temperature goes up , the frozen soil is melted, the setting of ground. So the ground is icy or melts causes and does not subside evenly . 7, Bridge foundation put on body, cave with stalactites and stalagmites, activity fault,etc. of coming down at the bad geology, may cause and does not subside evenly . 8, After the bridge is built up , the condition change of original ground . After most natural grounds and artificial grounds are soaked with water, especially usually fill out such soil of special ground as the soil , loess , expanding in the land ,etc., soil body intensity meet water drop, compress out of shape to strengthen. In the soft soil ground , season causes the water table to drop to draw water or arid artificially, the ground soil layer consolidates and sinks again, reduce the buoyancy on the foundation at the same time , shouldering the obstruction ofrubing to increase, the foundation is carried on one's shoulder or back and strengthened .Some bridge foundation is it put too shallow to bury, erode , is it dig to wash flood, the foundation might be moved. Ground load change of terms, bridge nearby is it is it abolish square , grit ,etc. in a large amount to put to pile with cave in , landslide ,etc. reason for instance, it is out of shape that the bridge location range soil layer may be compressed again. So, the condition of original ground change while using may cause and does not subside evenly Produce the structure thing of horizontal thrust to arched bridge ,etc., it is the main reason that horizontal displacement crack emerges to destroy the original geological condition when to that it is unreasonable to grasp incompletely , design and construct in the geological situation.桥梁裂缝产生原因浅析近年来，我省交通基础建设得到迅猛发展，各地兴建了大量的混凝土桥梁。
外文翻译---桥梁裂缝产生原因浅析
附录外文翻译A primary analysis on the causes of bridge cracksRecent years, the transportation infrustracture construction of our province has got a swift and violent development, and a large number of concrete bridges were built. However, in the courses of building and using these bridges, there are a lot of reports about the collapse of the bridges which are caused by the bridge cracks coming from time to time. Thus the concrete cracks can be called an often-occurring disease or an frequently-occuring disease which troubled a lot of the bridge engineering and technical personnel. However, if some measures can be taken during the design and construction of the bridge, many of the cracks can be controlled or even overcome. In order to enhance our understanding of the concrete bridge cracks and avoid the huge damage caused by the bridge cracks, this essay is thus writen to make a relatively detailed analysis and summary of the classification and causes of the concrete bridge cracks and will try to find some feasible ways to control the bridge cracks in the courses of design and building.There are various causes of the bridge cracks. Sometimes a bridge crack may influence each other. But the appearance of each crack has its own reason or reasons. In terms of the causes, the bridge cracks can be divided into the following types:First,cracks caused byloadThe cracks that are caused by the regular dynamic, static load or secondary stress are called load crack, which can be divided into direct stress cracks and secondary stress cracks. Direct stress crack refers to the cracks that are directly caused by the outside load stress. The causes of this kind of crack are as follows: 1, When calculating during the design stage, it does not calculate or calculates partly; Themodel is unreasonable; The structure supposed is not accorded with the actual strength ; Load is less or leak calculated; Internal forces and reinforcement calculation discounts; Safety coefficient of structure is not enough. Do not consider the possibility of construction at the time of the structural design; It is insufficient to design the section; It is simply little and assigning the mistake for reinforcing bars to set up; The structure rigidity is insufficient; Construct and deal with improperly; The design drawing can not be explained clearly etc.. 2,At the construction stage, does not pile up the machines , materials restrictively; Don't understand precast structure mechanical characteristics. Does it stand up , hang , transport , install are at will to understand; Construct not according to the design drawing. Alter the construction order of the structure without authorization. Change the structure strength mode; Do not do the tired intensity checking computations under machine of vibration condition etc.. 3, At the using stage, the heavy-duty vehicle which is beyond the design load passes the bridge; Receive the contact, striking of the vehicle, shipping; Strong wind, heavy snow, earthquake happen, explode etc.. Times stress cracks once means the stress of secondary caused by load outside produces the cracks. The reason why the cracks produce is as follows: 1, In designing outside load function, actual working condition and routine , structure of calculating have discrepancy or is are considered to calculate, thus cause stress once to make the structure to fracture in some position. For example, the arch feet design of two hinge arch bridge is often in decorate "X" form reinforced, while cutting down this section of design size. By means of the theoretical calculation, the department never exist bending moment , but actually should is it can resist curved still to the hinge, so it present the crack and cause the reinforcing bar corrosion. 2, Bridge structure is it dig trough , turn on hole , set up ox leg ,etc. to need often, difficult to use an accurate diagram to analog computation. It is general according to experience to set mechanical reinforced. Studies have shown that after mechanical components are dug hole, diffraction flow will produce. It gathers near the hole and produces the enormous stress concentration. In long span prestressed continuous beams, it is often to block the steel beam according to the needs of section internal force in the span, and set up the anchor head, but in near anchorage section can often see a crack. So if dealing with improperly, in the corner of the structure or components' shape mutations, stress reinforced truncation place easily crack. In the actual project, times stress cracks can be the most common reason which lead to load crack. Times stress cracks are tension, splitting, shear properties.Stress crack once is loaded and caused, only seldom calculates according to the routine too, but along with the continuous improvement of the modern computing method, times stress cracks can accomplish reasonable checking computations. For example, on the secondary stress produced by prestressing force, creep etc., many plane stem department finite element program all can calculate correctly, but it is more difficult 40 years ago. In the design, should pay attention to avoid structural break (or section mutation). When it is unable to avoid , should do local processing, such as corners do rounded corners, mutations make gradual transition, and strengthen constructional reinforcement at the same time. Corners increase oblique reinforced. For larger holes, if conditional, can install edge angles in the surrounding Settings. In accordance with the load characteristics, load cracks present different characteristics. This kind of cracks appear in more tensile crack, shear zone or severe vibration parts. But it must be pointed out, if pressure areas appear peeling or have short cracks along the compressive direction, it is often the symbol of structure can limit bearing capacity, it is an omen that the structure is destroyed. The reason is often that sectional size is partial and small. According to the different structure stress modes, the resulting crack characteristics are as follows: 1, Center tensile. Cross-section throughout component cracks. The spacings are approximately the same. The direction perpendicular to the force. When using thread steels, times cracks appear near reinforced between Cracks. 2, Center compression. Along the components of parallel to the stress direction appears short and secret parallel crack. 3, Bending terminal. Near bending moment maximum section, from the tensile crack edges appear tensile direction with vertical cracks. And gradually to neutralize axis direction. When using thread reinforced, between gaps appear shorter times crack. When constructional reinforcement is fewer, cracks are few and wide, the structure may happen brittle fracture. 4, Large eccentric compression. Large eccentric compression and small eccentric compression of lower tensile reinforcement, are similar to the flexural members. 5, Small eccentric compression. Small eccentric compression and large eccentric compression of more tensile reinforcement, are similar to the central compression members. 6, Shear. When the stirrup are too dense, baroclinic destruction happens. Along the girder ends 45°direction belly appear the diagonal crack; When stirrups are appropriate, shear compression failure occurs. Along the girder ends about 45°direction in the mid-lower appear parallel inclined cracks. 7, Torsion. Component side more than 45°comes first abdomen direction diagonalcrack of the treaty. And adjacent facets to spiral direction to unfold.8, Cutting. Along the stigma board inside four sides about 45°direction cant happen rip, forming a blunt cut. 9, Local compression. In local compression area appears multiple short cracks roughly parallelling the stress direction.Second, cracks caused by the change of the temperatureThe concrete has nature of expanding with heat and contract with cold, looking on as the external environment condition or the structure temperature changes, concrete takes place out of shape, if out of shape to restrain from, produce the stress in the structure, produce the temperature crack promptly when exceeding concrete tensile strength in stress. In some long-span bridges, temperature stress can is it reach live stress even to go beyond. The temperature crack distinguishes the main characteristic of other cracks will be varied with expanding or closing up with temperature. And the main factors are as follows, to cause temperature change: 1, Annual difference in temperature. Temperature is changing constantly in four seasons in one year, but changes relatively slowly, the impact on structure of the bridge is mainly the vertical displacement, can coordinate it by bridge expansion joint, support displacement, or setting up flexible pier, etc. Can cause temperature crack only when the displacement of the structure is limited, such as arch bridge, rigid frame bridge etc. The annual difference in temperature of our country generally changes the range with the conduct of the average temperature in the month of January and July. Considering the creep characteristic of the concrete, the elastic modulus of concrete should be considered fold reduction when the internal force of the annual difference in temperature is calculated. 2, Sunshine. After being tanned by the sun, floorings and the girder or the side of the pier, temperature is obviously higher than other positions. The temperature gradient is presented by nonlinear distribution. Due to the restriction by themselves, Lead to local tensile stress bigger. The crack appears. Sunshine and following to it most cause structural temperature crack. 3, Lower the temperature suddenly. Heavy rain, cold air attack , sunset, etc. can cause structure surface temperature drop suddenly. But inside temperature change relatively slow producing temperature gradient. Sunshine and lowering the temperature internal force can adopt design specification or consult real bridge materials to go on when calculating. Concrete elastic modulus amount does not consider fold reduction. 4, Heat of hydration. Appear in the course of constructing, After pouring the large volumeconcrete(thickness exceeds 2.0m), due to cement water hydrate and send out heat, causing inside very much high temperature, the internal and external difference in temperature is too large, causing the surface to appear the crack. Should according to actual conditions in constructing, try to choose the low hydration heat cement, limit cement's unit consumption, reduce the temperature aggregate into mold, reduce the internal and external difference in temperature, and lower the temperature slowly , can adopt the circulation cooling system to carry on the inside to dispel the heat in case of necessity, or adopt the thin layer and build it in succession in order to accelerate dispelling the heat. 5, The construction measure is improper at the time of steam maintenance or the winter construction , the concrete is suddenly cold and suddenly hot, internal and external temperature is uneven , apt to appear the crack. 6, Prefabricate T roof beam horizontal baffle when the installation , prop up seat bury stencil plate with transfer flat stencil plate when welding in advance, if weld measure to be improper, iron pieces of nearby concrete easy to is it fracture to burn. Using electro-thermal zhangrafa tension when tensing pre-stressed beam, prestressing force steels' temperature can rise to 350 degrees centigrade, the concrete component is apt to fracture. Experimental study indicates, caused by fire burns with high temperature strength of concrete significantly lower the temperature increasing, glueing forming the decline thereupon of strength of reinforcing bar and concrete, tensile strength drop by 50% after concrete temperature reaches 300 degrees centigrade, compression strength drops by 60%, glueing the strength of forming to drop by 80% of only round reinforcing bar and concrete; Because of heat, concrete body dissociate ink evaporate and can produce and shrink sharply in a large amount.Third, cracks caused by the contractionIn the actual project, concrete crack caused by shrinkage is the most common. Shrink kinds in concrete, plastic shrinkage and shrink contraction (air shrinkage) are to be the main reasons that the volume of concrete out of shape happens to shrink, autogenous shrinkage in addition and carbonized contraction. Plastic shrinkage. About 4~5 hours after it is built that in the course of constructing, concrete happens, the cement hydration reaction is fierce at this moment, the strand takes shape gradually, molecular chain gradually forms, secrete water and moisture to evaporate sharply, the concrete desiccates and shrinks, it is at the same time conducting aggregate sinking with dignity. Concrete has not yet hardened then, it iscalled plastic shrinkage. The plastic shrinkage's producing amount grade is very big, can be up to about 1%. If stopped by the reinforcing bar while the aggregate sinks, forming the crack along the reinforcing bar direction. Vertical cross-section place in the component such as T beam, a beam webs and roof and floor junction, before sclerosis uneven will occur, heavy fact along the direction of the surface of perforation cracks. For reducing concrete plastic shrinkage, it should control by water dust when being construct then, avoiding last long-time mixing, unloading should not be too quick. Is it take closely knit to smash to shake, vertical sectional place should divide layer build. Shrink contraction (air shrinkage). After the concrete is formed hard, as the top layer moisture is evaporated progressively, the humidity is reduced progressively, the volume of concrete is reduced, is called shrink contraction (air shrinkage). Because concrete top layer moisture loss soon, it is slow for inside to lose, produce surface shrink heavy, inside shrink a light one even to shrink, it is out of shape to restrain from by the inside concrete for surface to shrink, cause the surface concrete to bear pulling force, when the surface concrete bears pulling force to exceed its tensile strength, produce and shrink the crack. The concrete hardens after-contraction to just shrink contraction mainly .Such as the component with higher steel ratio (exceed 3% ), between reinforcing bar and more obvious restraints relatively that concrete shrink, the concrete surface is apt to appear in the full of cracks crackle. Autogenous shrinkage.Autogenous shrinkage is concrete to be in the course of hardenning , cement and water take place ink react. The shrink has nothing to do with external humidity, and can positive (whether shrink, such as ordinary portland cement concrete), can negative too (whether expand, such as concrete, concrete of slag cement and cement of fly ash). Carbonized contraction. Between carbon dioxide and hyrate of cement of atmosphere take place out of shape shrink that chemical reaction cause. Carbonized contraction could happen only about 50% of humidity, and accelerate with increase of the density of the carbon dioxide. The carbonized contraction seldom calculates. The characteristic that the concrete shrinks the crack is that the majority belongs to the surface crack, the crack is relatively detailed in width, and criss-cross, become the full of cracks form , the form does not have any law.Fourth, cracks caused by the deformation of the subgradeBecause foundation vertical to even to subside or horizontal directiondisplacement, make the structure produce the additional stress, go beyond resisting the ability of drawing of concrete structure, cause the structure to fracture. The even main reasons that differential settlement of the foundation are as follows: 1, Geological prospecting precision is insufficient and the testing materials are inaccurate in geology. Designing, constructing without fully grasping the geological situation, is the main reason that cause foundation uneven settlement. Such as hilly areas' bridges or district of mountain bridges, spacing of wells is too far when reconnoitring, and ground rises and falls frequently. The reconnoitring report can't fully reflect the real geological situation. 2, The geological difference of the ground is too large. Building the bridge in the valley of the ditch of mountain areas, geology of the stream place and place on the hillside change larger, even there is soft foundation in the stream, due to different foundation soil with different compressibility causes uneven settlement. 3, The structure loads' differences are too big. Under the unanimous terms, when every foundation too heavy to load difference in geological situation, may cause evenly to subside, such as high to fill out soil box culverts in the middle part of the culvert than to is it take heavy to load both sides, the middle part to subside soon heavy than both sides, casing it might fracture. 4, The difference of basic type of structure is great. Unite it in the bridge the samly, mix and use different foundations, such as expanding the foundation and pile foundations, or adopt a pile foundation when a pile diameter or a pile length differs greatly at the same time , or adopt the foundation of expanding when basis elevation is widely different at the same time , may cause the ground not to subside evenly too. 5, Foundation built by stages. In the newly-built bridge near the foundation of original bridge, if the half a bridge about expressway built by stages, the newly-built bridge loads or the foundation causes the soil of the ground to consolidate again while dealing with, may cause and subside the foundation of original bridge greatly. 6, The subgrade is frozen bloatedly. The ground soil of higher moisture content on terms that lower than zero degree expands because of being icy; Once temperature goes up, the frozen soil is melted, the foundation sinks. So the foundation's frost or melting causes differential settlement evenly. 7, Bridge foundation put on body, cave with stalactites and stalagmites, activity fault, etc. of coming down at the bad geology, may cause differential settlement evenly. 8, After the bridge is built up, the condition of original ground changed. After most natural grounds and artificial grounds are soaked with water, especially plain fill, loess, swelled ground, etc., the soil body intensitydrops when meeting water, the compression increases. In the soft soil foundation, season or arid artificially cause the water table to drop, the ground soil layer consolidates and sinks again, reduce the buoyancy on the foundation at the same time. Negative friction increases, the load stand by foundation strengthens. Some bridge foundation is put too shallow to erode, dig, the foundation might be moved. Ground load change of terms, such as bridge nearby happens collapse, landslide, etc. reason for instance, banking up plenty of waste square, dinas. it is out of shape that the bridge location range soil layer may be compressed again. So, the condition of original foundation changes while using may cause differential settlement evenly. Produce the structure thing of horizontal thrust to arched bridges, etc., it is the main reason that horizontal displacement crack emerges to destroy the original geological condition when to that it is unreasonable to grasp completely, design and construct in the geological situation.桥梁裂缝产生原因浅析近年来，我省交通基础建设得到迅猛发展，各地兴建了大量的混凝土桥梁。
论混凝土的施工温度与结构裂缝外文翻译17页word
论混凝土的施工温度与结构裂缝外文翻译On the construction of concrete temperature and cracks1. the causes of the cracksCracks in concrete are a variety of reasons, mainly temperature and humidity changes, brittle and uneven concrete, as well as the structure is irrational, failure of raw materials (such as alkali-aggregate reaction), template deformation, and so on the basis of differential settlement.The concrete to harden off a large number of cement during the hydration heat, the internal temperature rising on the surface caused by tensile stress. Late in the cooling process, due to coagulation on the basis of or be bound by the old, will emerge in the concrete tensile stress. Lower temperatures in the concrete surface will be a lot of tensile stress. When the tensile stress beyond the capacity of concrete crack, the cracks will appear. A number of concrete changes in the internal humidity or changes very little slow, but possible changes in surface humidity or more dramatic changes. Such as conservation, failed to keep dry when wet, surface shrinkage deformation of concrete subject to internal constraints, but also often leads to cracks. Short-term loading at the time of ultimate tensile deformation only (0.6 ~ 1.0) × 104, the limit of long-term loading spaces when the only stretch deformation (1.2 ~ 2.0) × 104. Unevenly as a result of raw materials, water-cement ratio of instability, and transportation and pouring in the process of segregation phenomena, in the same piece of concrete in the tensile strength is uneven,there are many low tensile capacity, easy to fracture in a weak position. In reinforced concrete, the tensile stress is mainly borne by the steel, concrete is subject to compressive stress. In plain concrete or reinforced coagulation on the edge of the site if the structure of the tensile stress appears to be relying on its own concrete共12 页commitment.2. thermal stress analysisAccording to the formation of thermal stress can be divided into the following three stages:(1)early: Since the beginning of pouring concrete to cement the end of exothermic basic general about 30 days. Two characteristics of this stage, first, to release a large number of cement hydration heat, and the other is the elastic modulus of coagulation dramatic changes. Modulus of elasticity as a result of changes within this period in the formation of residual stress in the concrete.(2) medium-term: from the basic role of cement heat until the end of the stable temperature of the concrete cooling time, during this period, the temperature stress was mainly due to cooling and the outside concrete caused by temperature changes, stress and early formation of these residual stress superposition phase, during which the coagulation of the elastic modulus changed little.(3) late: concrete completely cooling period after the operation. Thermal stress is mainly caused by external temperature changes, the stress and the first two-phase superposition of residual stress.Under the thermal stress caused by the reasons can be divided into two categories:(1) self-stress: there is no constraint on the border or completely static structure, if the internal temperature distribution is nonlinear, due to structural constraints arising from their co-temperature stress. For example, the conversion layer of its relatively larger size, concrete cooling surface temperature low, the internal temperatures are high, the surface tensile stress, compressive stress appears in the middle.(2) bound by stress: the structure of all or part of the boundary bound by the outside world can not be free-form deformation caused by stress. Roof box,共12 页such as concrete and concrete barrier.Both the temperature and the concrete stress is often caused by shrinkage of the combined effect of stress.Known to be in accordance with an accurate analysis of the temperature of the thermal stress distribution, size is a more complex task. In most cases, the need to rely on model test or numerical calculation. Creep of concrete so that the temperature there is considerable stress relaxation, thermal stresscalculation, we must consider the effects of creep, is no longer calculated in detail here.3. temperature control and measures to prevent the cracksIn order to prevent cracking, reduce the thermal stress can control the conditions of temperature and to improve the binding of two aspects.Temperature control measures are as follows:(1) used to improve the aggregate gradation, dry hard concrete, mixed mixture, add air-entraining agent or plasticizer, etc. measures to reduce the amount of cement concrete;(2) mixing concrete by adding water or cooling water will be gravel and pouring concrete to reduce the temperature;(3) pouring hot days to reduce the pouring of concrete thickness, the use of pouring heat levels;(4) laid in concrete water pipes, access to cold water to cool;(5) the provisions of reasonable time, the temperature drop when the surface insulation, concrete surface in order to avoid a sharp temperature gradient;(6) Construction of long-term exposure to block the surface of the concrete pouring, or thin-walled structures, thermal insulation in the cold season to take measures;Measures to improve the constraints are:共12 页(1) a reasonable sub-block joints;(2) basis to avoid too much ups and downs;(3) reasonable arrangements for the construction process, to avoid excessive side elevation and long-term exposure;In addition, to improve the performance of concrete to improve theanti-cracking ability, to strengthen the conservation, to prevent surface drying, in particular, is to ensure the quality of concrete is very important to prevent cracks, should pay special attention to avoid cross-cracks appears to restore the integrity of its structure it is very difficult, so the construction should be to prevent the occurrence of cross-cutting the main crack.In concrete construction, in order to increase the turnover rate of the template, often require new pouring concrete as soon as possible. When the concrete temperature is higher than the temperature should be appropriate to consider time, so as to avoid the early cracks in the concrete surface. New pouring early, a lot of the surface tensile stress, a "temperature shock" phenomenon. Concrete pouring in the early heat of hydration as a result of the dissemination of the surface caused by a large tensile stress, when the surface temperature is higher than the temperature at this time to remove the template, a sharp fall in surface temperature is bound to lead to temperature gradient, so an additional one on the surface tensile stress, thermal stress superposition and hydration, coupled with the shrinkage of concrete, Tensile stress to reach the surface of great value, there is the danger oflead to cracks, but if in a timely manner after the removal of the template on the surface coverage of a light insulating material, such as foam sponge and so on, have a concrete surface to prevent excessive tensile stress, with significant results.Reinforced concrete on the large volume of thermal stress has little effect because the large volume of concrete reinforced with a very low rate. Only on 共12 页the general impact of reinforced concrete. Not too high in temperature and stress below the yield limit under the condition of the properties of steel is stable, and with the stress, time and temperature has nothing to do. Linear expansion coefficient of steel and concrete linear expansion coefficient difference between the small changes in temperature between the two with only a very small stress. Since the modulus of elasticity of steel to concrete elastic modulus of 7 ~ 15-fold, when the stress reached the tensile strength of concrete and cracking, the steel stress will not exceed 100 ~ 200kg/cm2 .. So , Want to use in reinforced concrete to prevent the emergence of small cracks is difficult. However, after the reinforced structure of the number of cracks in general has become more than a small distance, a smaller width and depth. And if the diameter of steel thin and close spacing, the crack resistance of concrete to enhance the effect of better. Concrete and reinforced concrete structure of the surface often occur cracks in thin and shallow, most of them belonging to shrinkage cracks. While this is generally shallow cracks, but itsstrength and durability of the structure is still a certain impact.In order to ensure the quality of concrete to prevent cracking and improve the durability of concrete, the proper use of admixtures is also one of the measures to reduce cracking. Such as the use of anti-cracking agent and water, in practice, its major role in concluding as follows:(1) the existence of a large number of pores in the concrete that, after evaporation of water generated by capillary capillary tension, deformation of the concrete shrinkage. Pores increased capillary diameter can reduce the surface tension, but would reduce the strength of concrete.(2) the impact of water-cement ratio is an important factor for concrete shrinkage, the use of anti-cracking agent can reduce water consumption reduced by 25% concrete.(3) the amount of cement concrete is also an important factor in shrinkage,共12 页water addition and subtraction mixed concrete cracking agent in maintaining the strength of concrete under the condition of 15 percent can reduce the amount of cement, aggregate size, by increasing the amount to supplement.(4) anti-cracking agent and water can improve the consistency of cement slurry to reduce the bleeding of concrete, reduce shrinkage deformation Shen.(5) to improve and cement bonded aggregate, and enhance theanti-cracking performance of concrete.(6) concrete bound in the contraction produced by tensile stress, when the tensile stress is greater than the tensile strength of concrete will be produced when the cracks. Water-reducing agent can be an effectiveanti-cracking of the concrete tensile strength to increase, a substantial increase in anti-cracking performance of concrete.(7) mixing-compacting concrete admixtures can, and can effectively improve the carbonation resistance of concrete to reduce the carbonation shrinkage.(8)-doped water-reducing agent after the concrete cracking retardation time due, in the effective prevention of the rapid hydration heat of cement based on cement to avoid long-term result of non-condensable increase plastic shrinkage.(9)-doped workability of concrete admixtures, and easy to find flat surfaces to form a micro-membrane to reduce evaporation and reduce drying shrinkage.Many have a retarding admixture to increase the workability and improve the function of plasticity, we in engineering practice in this area should be more contrast and research experiments than simply relying on external conditions to improve may be even more simple and economic.4. early concrete conservationPractice has proved that the common concrete cracks, the majority ofsurface cracks at different depths, mainly because of the temperature gradient caused by the cold temperature region is also vulnerable to a sharp fall in the formation共12 页of cracks. Insulation so that the concrete surface to prevent early cracking is particularly important.Thermal stress from the point of view, the insulation should meet the following requirements:(1) to prevent the concrete inside and outside the concrete surface temperature difference and gradient, to prevent surface cracks.(2) to prevent the concrete super-cold, it should be possible to make concrete the construction period of not less than the minimum temperature of concrete used for the stability of the temperature.(3) to prevent cold-old concrete in order to reduce the concrete between the old and new constraints.Early concrete conservation, the main objective is to maintain the appropriate temperature and humidity conditions in order to achieve the effect of two aspects, on the one hand, the concrete from adverse temperature and humidity deformation invasion to prevent the harmful and drying shrinkage. On the one hand, to enable the smooth progress of cement hydration, with a view to meet the design capacity of the strength and crack resistance.Appropriate conditions of temperature and humidity are interrelated. Coagulation on the insulation often has the effect of moisture.Theoretical analysis of fresh concrete contained in the water fully meets the requirements of cement hydration and more than. However, due to evaporation and other factors often cause water loss, thereby delay or prevent the hydration of cement, concrete surface and most likely to be directly affected by such a negative impact. Concrete pouring, therefore the first few days after the critical period of conservation in the construction should pay attention to.5. concluding remarksAbove the temperature of concrete and cracks in the construction of the 共12 页relation between theory and practice of the preliminary study, although the academic community about the causes of cracks in concrete and calculation methods are different theories, but specific measures to prevent and improve the opinion it is quite uniform At the same time, the application in practice is also a relatively good effect, concrete construction and more depends on our observation, and more, when compared to multi-issue analysis, and more sum up, combined with a wide range of prevention measures, the cracks in the concrete is completely avoided.论混凝土的施工温度与结构裂缝1.裂缝的原因混凝土中产生裂缝有多种原因，主要是温度和湿度的变化，混凝土的脆性和不均匀性，以及结构不合理，原材料不合格（如碱骨料反应），模板变形，基础不均匀沉降等。
土木毕业设计外文翻译---桥梁裂缝产生原因浅析
外文文献原文The bridge crack produced the reason to simply analyseIn recent years, the traffic capital construction of our province gets swift and violent development, all parts have built a large number of concrete bridges. In the course of building and using in the bridge, relevant to influence project quality lead of common occurrence report that bridge collapse even because the crack appears The concrete can be said to " often have illness coming on " while fracturing and " frequently-occurring disease ", often perplex bridge engineers and technicians. In fact , if take certain design and construction measure, a lot of cracks can be overcome and controlled. For strengthen understanding of concrete bridge crack further, is it prevent project from endanger larger crack to try one's best, this text make an more overall analysis , summary to concrete kind and reason of production , bridge of crack as much as possible, in order to design , construct and find out the feasible method which control the crack , get the result of taking precautions against Yu WeiRan.Concrete bridge crack kind, origin cause of formation In fact, the origin cause of formation of the concrete structure crack is complicated and various, even many kinds of factors influence each other , but every crack has its one or several kinds of main reasons produced . The kind of the concrete bridge crack, on its reason to produce, can roughly divide several kinds as follows :(1) load the crack caused Concrete in routine quiet .Is it load to move and crack that produce claim to load the crack under the times of stress bridge, summing up has direct stress cracks , two kinds stress crack onces mainly. Direct stress crack refer to outside load direct crack that stress produce that cause. The reason why the crack produces is as follows, 1, Design the stage of calculating , does not calculate or leaks and calculates partly while calculating in structure; Calculate the model is unreasonable; The structure is supposed and accorded with by strength actually by strength ; Load and calculate or leak and calculate few; Internal force and matching the mistake in computation of muscle; Safety coefficient of structure is not enough. Do not consider the possibility that construct at the time of the structural design; It is insufficientto design the section; It is simply little and assigning the mistake for reinforcing bar to set up; Structure rigidity is insufficient; Construct and deal with improperly; The design drawing can not be explained clearly etc.. 2, Construction stage, does not pile up and construct the machines , material limiting ; Is it prefabricate structure structure receive strength characteristic , stand up , is it hang , transport , install to get up at will to understand; Construct not according to the design drawing, alter the construction order of the structure without authorization , change the structure and receive the strength mode; Do not do the tired intensity checking computations under machine vibration and wait to the structure . 3, Using stage, the heavy-duty vehicle which goes beyond the design load passes the bridge; Receive the contact , striking of the vehicle , shipping; Strong wind , heavy snow , earthquake happen , explode etc.. Stress crack once means the stress of secondary caused by loading outside produces the crack. The reason why the crack produces is as follows, 1, In design outside load function , because actual working state and routine , structure of thing calculate have discrepancy or is it consider to calculate, thus cause stress once to cause the structure to fracture in some position. Two is it join bridge arch foot is it is it assign " X " shape reinforcing bar , cut down this place way , section of size design and cut with scissors at the same time to adopt often to design to cut with scissors, theory calculate place this can store curved square in , but reality should is it can resist curved still to cut with scissors, so that present the crack and cause the reinforcing bar corrosion. 2, Bridge structure is it dig trough , turn on hole , set up ox leg ,etc. to need often, difficult to use a accurate one diagrammatic to is it is it calculate to imitate to go on in calculating in routine, set up and receive the strength reinforcing bar in general foundation experience. Studies have shown , after being dug the hole by the strength component , it will produce the diffraction phenomenon that strength flows, intensive near the hole in a utensil, produced the enormous stress to concentrate. In long to step prestressing force of the continuous roof beam , often block the steel bunch according to the needs of section internal force in stepping, set up the anchor head, but can often see the crack in the anchor firm section adjacent place. So if deal with improper, in corner or component form sudden change office , block place to be easy to appear crack strengthreinforcing bar of structure the. In the actual project, stress crack once produced the most common reason which loads the crack. Stress crack once belong to one more piece of nature of drawing , splitting off , shearing. Stress crack once is loaded and caused, only seldom calculate according to the routine too, but with modern to calculate constant perfection of means, times of stress crack to can accomplish reasonable checking computations too. For example to such stresses 2 times of producing as prestressing force , creeping ,etc., department's finite element procedure calculates levels pole correctly now, but more difficult 40 years ago. In the design, should pay attention to avoiding structure sudden change (or section sudden change), when it is unable to avoid , should do part deal with , corner for instance, make round horn , sudden change office make into the gradation zone transition, is it is it mix muscle to construct to strengthen at the same time, corner mix again oblique to reinforcing bar , as to large hole in a utensil can set up protecting in the perimeter at the terms of having angle steel. Load the crack characteristic in accordance with loading differently and presenting different characteristics differently. The crack appear person who draw more, the cutting area or the serious position of vibration. Must point out , is it get up cover or have along keep into short crack of direction to appear person who press, often the structure reaches the sign of bearing the weight of strength limit, it is an omen that the structure is destroyed, its reason is often that sectional size is partial and small. Receive the strength way differently according to the structure, the crack characteristic produced is as follows: 1, The centre is drawn. The crack runs through the component cross section , the interval is equal on the whole , and is perpendicular to receiving the strength direction. While adopting the whorl reinforcing bar , lie in the second-class crack near the reinforcing bar between the cracks. 2, The centre is pressed. It is parallel on the short and dense parallel crack which receive the strength direction to appear along the component. 3, Receive curved. Most near the large section from border is it appear and draw into direction vertical crack to begin person who draw curved square, and develop toward neutralization axle gradually. While adopting the whorl reinforcing bar , can see shorter second-class crack among the cracks. When the structure matches muscles less, there are few but wide cracks, fragility destruction may take place in thestructure 4, Pressed big and partial. Heavy to press and mix person who draw muscle a less one light to pigeonhole into the component while being partial while being partial, similar to receiving the curved component. 5, Pressed small and partial. Small to press and mix person who draw muscle a more one heavy to pigeonhole into the component while being partial while being partial, similar to the centre and pressed the component. 6, Cut. Press obliquly when the hoop muscle is too dense and destroy, the oblique crack which is greater than 45?? direction appears along the belly of roof beam end; Is it is it is it destroy to press to cut to happen when the hoop muscle is proper, underpart is it invite 45?? direction parallel oblique crack each other to appear along roof beam end. 7, Sprained. Component one side belly appear many direction oblique crack, 45?? of treaty, first, and to launch with spiral direction being adjoint. 8, Washed and cut. 4 side is it invite 45?? direction inclined plane draw and split to take place along column cap board, form the tangent plane of washing. 9, Some and is pressed. Some to appear person who press direction roughly parallel large short cracks with pressure.(2) crack caused in temperature changeThe concrete has nature of expanding with heat and contract with cold, look on as the external environment condition or the structure temperature changes, concrete take place out of shape, if out of shape to restrain from, produce the stress in the structure, produce the temperature crack promptly when exceeding concrete tensile strength in stress. In some being heavy to step foot-path among the bridge , temperature stress can is it go beyond living year stress even to reach. The temperature crack distinguishes the main characteristic of other cracks will be varied with temperature and expanded or closed up. The main factor is as follows, to cause temperature and change 1, Annual difference in temperature. Temperature is changing constantly in four seasons in one year, but change relatively slowly, the impact on structure of the bridge is mainly the vertical displacement which causes the bridge, can prop up seat move or set up flexible mound ,etc. not to construct measure coordinate , through bridge floor expansion joint generally, can cause temperature crack only when the displacement of the structure is limited, for example arched bridge , just bridge etc. The annual difference in temperature of our country generally changes therange with the conduct of the average temperature in the moon of January and July. Considering the creep characteristic of the concrete, the elastic mould amount of concrete should be considered rolling over and reducing when the internal force of the annual difference in temperature is calculated. 2, Rizhao. After being tanned by the sun by the sun to the side of bridge panel , the girder or the pier, temperature is obviously higher than other position, the temperature gradient is presented and distributed by the line shape . Because of restrain oneself function, cause part draw stress to be relatively heavy, the crack appears. Rizhao and following to is it cause structure common reason most , temperature of crack to lower the temperature suddenly 3, Lower the temperature suddenly. Fall heavy rain , cold air attack , sunset ,etc. can cause structure surface temperature suddenly dropped suddenly, but because inside temperature change relatively slow producing temperature gradient. Rizhao and lower the temperature internal force can adopt design specification or consult real bridge materials go on when calculating suddenly, concrete elastic mould amount does not consider converting into and reducing 4, Heat of hydration. Appear in the course of constructing, the large volume concrete (thickness exceeds 2. 0), after building because cement water send out heat, cause inside very much high temperature, the internal and external difference in temperature is too large, cause the surface to appear in the crack. Should according to actual conditions in constructing, is it choose heat of hydration low cement variety to try one's best, limit cement unit's consumption, reduce the aggregate and enter the temperature of the mould , reduce the internal and external difference in temperature, and lower the temperature slowly , can adopt the circulation cooling system to carry on the inside to dispel the heat in case of necessity, or adopt the thin layer and build it in succession in order to accelerate dispelling the heat. 5, The construction measure is improper at the time of steam maintenance or the winter construction , the concrete is sudden and cold and sudden and hot, internal and external temperature is uneven , apt to appear in the crack. 6, Prefabricate T roof beam horizontal baffle when the installation , prop up seat bury stencil plate with transfer flat stencil plate when welding in advance, if weld measure to be improper, iron pieces of nearby concrete easy to is it fracture to burn. Adopt electric heat piece draw law piece draw prestressing force at the component ,prestressing force steel temperature can rise to 350 degrees Centigrade , the concrete component is apt to fracture. Experimental study indicates , are caused the intensity of concrete that the high temperature burns to obviously reduce with rising of temperature by such reasons as the fire ,etc., glueing forming the decline thereupon of strength of reinforcing bar and concrete, tensile strength drop by 50% after concrete temperature reaches 300 degrees Centigrade, compression strength drops by 60%, glueing the strength of forming to drop by 80% of only round reinforcing bar and concrete; Because heat, concrete body dissociate ink evaporate and can produce and shrink sharply in a large amount(3) shrink the crack causedIn the actual project, it is the most common because concrete shrinks the crack caused. Shrink kind in concrete, plasticity shrink is it it shrinks (is it contract to do ) to be the main reason that the volume of concrete out of shape happens to shrink, shrink spontaneously in addition and the char shrink. Plasticity shrink. About 4 hours after it is built that in the course of constructing , concrete happens, the cement water response is fierce at this moment, the strand takes shape gradually, secrete water and moisture to evaporate sharply, the concrete desiccates and shrinks, it is at the same time conduct oneself with dignity not sinking because aggregate,so when harden concrete yet,it call plasticity shrink. The plasticity shrink producing amount grade is very big, can be up to about 1%. If stopped by the reinforcing bar while the aggregate sinks, form the crack along the reinforcing bar direction. If web , roof beam of T and roof beam of case and carry baseplate hand over office in component vertical to become sectional place, because sink too really to superficial obeying the web direction crack will happen evenly before hardenning. For reducing concrete plasticity shrink,it should control by water dust when being construct than,last long-time mixing, unloading should not too quick, is it is it take closely knit to smash to shake, vertical to become sectional place should divide layer build. Shrink and shrink (do and contract). After the concrete is formed hard , as the top layer moisture is evaporated progressively , the humidity is reduced progressively , the volume of concrete is reduced, is called and shrunk to shrink (do and contract). Because concrete top layermoisture loss soon, it is slow for inside to lose, produce surface shrink heavy , inside shrink a light one even to shrink, it is out of shape to restrain from by the inside concrete for surface to shrink, cause the surface concrete to bear pulling force, when the surface concrete bears pulling force to exceed its tensile strength, produce and shrink the crack. The concrete hardens after-contraction to just shrink and shrink mainly .Such as mix muscle rate heavy component (exceed 3% ), between reinforcing bar and more obvious restraints relatively that concrete shrink, the concrete surface is apt to appear in the full of cracks crackle. Shrink spontaneously. Spontaneous to it shrinks to be concrete in the course of hardenning , cement and water take place ink react, the shrink with have nothing to do by external humidity, and can positive (whether shrink, such as ordinary portland cement concrete), can negative too (whether expand, such as concrete, concrete of slag cement and cement of fly ash). The char shrinks. Between carbon dioxide and hyrate of cement of atmosphere take place out of shape shrink that chemical reaction cause. The char shrinks and could happen only about 50% of humidity, and accelerate with increase of the density of the carbon dioxide. The char shrinks and seldom calculates . The characteristic that the concrete shrinks the crack is that the majority belongs to the surface crack, the crack is relatively detailed in width , and criss-cross, become the full of cracks form , the form does not have any law . Studies have shown , influence concrete shrink main factor of crack as follows, 1, Variety of cement , grade and consumption. Slag cement , quick-hardening cement , low-heat cement concrete contractivity are relatively high, ordinary cement , volcanic ash cement , alumina cement concrete contractivity are relatively low. Cement grade low in addition, unit volume consumption heavy rubing detailed degree heavy, then the concrete shrinks the more greatly, and shrink time is the longer. For example, in order to improve the intensity of the concrete , often adopt and increase the cement consumption method by force while constructing, the result shrinks the stress to obviously strengthen . 2, Variety of aggregate. Such absorbing water rates as the quartz , limestone , cloud rock , granite , feldspar ,etc. are smaller, contractivity is relatively low in the aggregate; And such absorbing water rates as the sandstone , slate , angle amphibolite ,etc. are greater, contractivity is relatively high. Aggregate grains of foot-path heavy to shrink light inaddition, water content big to shrink the larger. 3, Water gray than. The heavier water consumption is, the higher water and dust are, the concrete shrinks the more greatly. 4, Mix the pharmaceutical outside. It is the better to mix pharmaceutical water-retaining property outside, then the concrete shrinks the smaller. 5, Maintain the method . Water that good maintenance can accelerate the concrete reacts, obtain the intensity of higher concrete. Keep humidity high , low maintaining time to be the longer temperature when maintaining, then the concrete shrinks the smaller. Steam maintain way than maintain way concrete is it take light to shrink naturall. 6, External environment. The humidity is little, the air drying , temperature are high, the wind speed is large in the atmosphere, then the concrete moisture is evaporated fast, the concrete shrinks the faster. 7, Shake and smash the way and time. Machinery shake way of smashing than make firm by ramming or tamping way concrete contractivity take little by hand. Shaking should determine according to mechanical performance to smash time , are generally suitable for 55s / time. It is too short, shake and can not smash closely knit , it is insufficient or not even in intensity to form the concrete; It is too long, cause and divide storey, thick aggregate sinks to the ground floor, the upper strata that the detailed aggregate stays, the intensity is not even , the upper strata incident shrink the crack. And shrink the crack caused to temperature, worthy of constructing the reinforcing bar againing can obviously improve the resisting the splitting of concrete , structure of especially thin wall (thick 200cm of wall ). Mix muscle should is it adopt light diameter reinforcing bar (8 |? construct 14 |? ) to have priority , little interval assign (whether @ 10 construct @ 15cm ) on constructing, the whole section is it mix muscle to be rate unsuitable to be lower than 0 to construct. 3%, can generally adopt 0 . 3%~0. 5%.(4), crack that causes out of shape of plinth of the groundBecause foundation vertical to even to subside or horizontal direction displacement, make the structure produce the additional stress, go beyond resisting the ability of drawing of concrete structure, cause the structure to fracture. The even main reason that subside of the foundation is as follows, 1, Reconnoitres the precision and is not enough for , test the materials inaccuratly in geology. Designing, constructing without fully grasping the geological situation, this is the main reason that cause the ground not to subside evenly .Such as hills area or bridge, district of mountain ridge,, hole interval to be too far when reconnoitring, and ground rise and fall big the rock, reconnoitring the report can't fully reflect the real geological situation . 2, The geological difference of the ground is too large. Building it in the bridge of the valley of the ditch of mountain area, geology of the stream place and place on the hillside change larger, even there are weak grounds in the stream, because the soil of the ground does not causes and does not subside evenly with the compressing. 3, The structure loads the difference too big. Under the unanimous terms, when every foundation too heavy to load difference in geological situation, may cause evenly to subside, for example high to fill out soil case shape in the middle part of the culvert than to is it take heavy to load both sides, to subside soon heavy than both sides middle part, case is it might fracture to contain 4, The difference of basic type of structure is great. Unite it in the bridge the samly , mix and use and does not expand the foundation and a foundation with the foundation, or adopt a foundation when a foot-path or a long difference is great at the same time , or adopt the foundation of expanding when basis elevation is widely different at the same time , may cause the ground not to subside evenly too 5, Foundation built by stages. In the newly-built bridge near the foundation of original bridge, if the half a bridge about expressway built by stages, the newly-built bridge loads or the foundation causes the soil of the ground to consolidate again while dealing with, may cause and subside the foundation of original bridge greatly 6, The ground is frozen bloatedly. The ground soil of higher moisture content on terms that lower than zero degree expands because of being icy; Once temperature goes up , the frozen soil is melted, the setting of ground. So the ground is icy or melts causes and does not subside evenly . 7, Bridge foundation put on body, cave with stalactites and stalagmites, activity fault,etc. of coming down at the bad geology, may cause and does not subside evenly . 8, After the bridge is built up , the condition change of original ground . After most natural grounds and artificial grounds are soaked with water, especially usually fill out such soil of special ground as the soil , loess , expanding in the land ,etc., soil body intensity meet water drop, compress out of shape to strengthen. In the soft soil ground , season causes the water table to drop to draw water or arid artificially, the ground soil layer consolidates and sinks again,reduce the buoyancy on the foundation at the same time , shouldering the obstruction of rubing to increase, the foundation is carried on one's shoulder or back and strengthened .Some bridge foundation is it put too shallow to bury, erode , is it dig to wash flood, the foundation might be moved. Ground load change of terms, bridge nearby is it is it abolish square , grit ,etc. in a large amount to put to pile with cave in , landslide ,etc. reason for instance, it is out of shape that the bridge location range soil layer may be compressed again. So, the condition of original ground change while using may cause and does not subside evenly Produce the structure thing of horizontal thrust to arched bridge ,etc., it is the main reason that horizontal displacement crack emerges to destroy the original geological condition when to that it is unreasonable to grasp incompletely , design and construct in the geological situation.目录桥梁裂缝产生原因浅析 (11)一、荷载引起的裂缝 (11)二、温度变化引起的裂缝 (13)三、收缩引起的裂缝 (14)四、地基础变形引起的裂缝 (15)桥梁裂缝产生原因浅析近年来，我省交通基础建设得到迅猛发展，各地兴建了大量的混凝土桥梁。
道路与桥梁工程中英文对照外文翻译文献
中英文对照外文翻译(文档含英文原文和中文翻译)Bridge research in EuropeA brief outline is given of the development of the European Union, together with the research platform in Europe. The special case of post-tensioned bridges in the UK is discussed. In order to illustrate the type of European research being undertaken, an example is given from the University of Edinburgh portfolio: relating to the identification of voids in post-tensioned concrete bridges using digital impulse radar.IntroductionThe challenge in any research arena is to harness the findings of different research groups to identify a coherent mass of data, which enables research and practice to be better focused. A particular challenge exists with respect to Europe where language barriers are inevitably very significant. The European Community was formed in the 1960s based upon a political will within continental Europe to avoid the European civil wars, which developed into World War 2 from 1939 to 1945. The strong political motivation formed the original community of which Britain was not a member. Many of the continental countries saw Britain’s interest as being purelyeconomic. The 1970s saw Britain joining what was then the European Economic Community (EEC) and the 1990s has seen the widening of the community to a European Union, EU, with certain political goals together with the objective of a common European currency.Notwithstanding these financial and political developments, civil engineering and bridge engineering in particular have found great difficulty in forming any kind of common thread. Indeed the educational systems for University training are quite different between Britain and the European continental countries. The formation of the EU funding schemes —e.g. Socrates, Brite Euram and other programs have helped significantly. The Socrates scheme is based upon the exchange of students between Universities in different member states. The Brite Euram scheme has involved technical research grants given to consortia of academics and industrial partners within a number of the states— a Brite Euram bid would normally be led by an industrialist.In terms of dissemination of knowledge, two quite different strands appear to have emerged. The UK and the USA have concentrated primarily upon disseminating basic research in refereed journal publications: ASCE, ICE and other journals. Whereas the continental Europeans have frequently disseminated basic research at conferences where the circulation of the proceedings is restricted.Additionally, language barriers have proved to be very difficult to break down. In countries where English is a strong second language there has been enthusiastic participation in international conferences based within continental Europe —e.g. Germany, Italy, Belgium, The Netherlands and Switzerland. However, countries where English is not a strong second language have been hesitant participants }—e.g. France.European researchExamples of research relating to bridges in Europe can be divided into three types of structure:Masonry arch bridgesBritain has the largest stock of masonry arch bridges. In certain regions of the UK up to 60% of the road bridges are historic stone masonry arch bridges originally constructed for horse drawn traffic. This is less common in other parts of Europe as many of these bridges were destroyed during World War 2.Concrete bridgesA large stock of concrete bridges was constructed during the 1950s, 1960s and 1970s. At the time, these structures were seen as maintenance free. Europe also has a large number of post-tensioned concrete bridges with steel tendon ducts preventing radar inspection. This is a particular problem in France and the UK.Steel bridgesSteel bridges went out of fashion in the UK due to their need for maintenance as perceived in the 1960s and 1970s. However, they have been used for long span and rail bridges, and they are now returning to fashion for motorway widening schemes in the UK.Research activity in EuropeIt gives an indication certain areas of expertise and work being undertaken in Europe, but is by no means exhaustive.In order to illustrate the type of European research being undertaken, an example is given from the University of Edinburgh portfolio. The example relates to the identification of voids in post-tensioned concrete bridges, using digital impulse radar.Post-tensioned concrete rail bridge analysisOve Arup and Partners carried out an inspection and assessment of the superstructure of a 160 m long post-tensioned, segmental railway bridge in Manchester to determine its load-carrying capacity prior to a transfer of ownership, for use in the Metrolink light rail system..Particular attention was paid to the integrity of its post-tensioned steel elements. Physical inspection, non-destructive radar testing and other exploratory methods were used to investigate for possible weaknesses in the bridge.Since the sudden collapse of Ynys-y-Gwas Bridge in Wales, UK in 1985, there has been concern about the long-term integrity of segmental, post-tensioned concrete bridges which may b e prone to ‘brittle’ failure without warning. The corrosion protection of the post-tensioned steel cables, where they pass through joints between the segments, has been identified as a major factor affecting the long-term durability and consequent strength of this type of bridge. The identification of voids in grouted tendon ducts at vulnerable positions is recognized as an important step in the detection of such corrosion.Description of bridgeGeneral arrangementBesses o’ th’ Barn Bridge is a 160 m long, three span, segmental, post-tensionedconcrete railway bridge built in 1969. The main span of 90 m crosses over both the M62 motorway and A665 Bury to Prestwick Road. Minimum headroom is 5.18 m from the A665 and the M62 is cleared by approx 12.5 m.The superstructure consists of a central hollow trapezoidal concrete box section 6.7 m high and 4 m wide. The majority of the south and central spans are constructed using 1.27 m long pre-cast concrete trapezoidal box units, post-tensioned together. This box section supports the in site concrete transverse cantilever slabs at bottom flange level, which carry the rail tracks and ballast.The center and south span sections are of post-tensioned construction. These post-tensioned sections have five types of pre-stressing:1. Longitudinal tendons in grouted ducts within the top and bottom flanges.2. Longitudinal internal draped tendons located alongside the webs. These are deflected at internal diaphragm positions and are encased in in site concrete.3. Longitudinal macalloy bars in the transverse cantilever slabs in the central span .4. Vertical macalloy bars in the 229 mm wide webs to enhance shear capacity.5. Transverse macalloy bars through the bottom flange to support the transverse cantilever slabs.Segmental constructionThe pre-cast segmental system of construction used for the south and center span sections was an alternative method proposed by the contractor. Current thinking suggests that such a form of construction can lead to ‘brittle’ failure of the ent ire structure without warning due to corrosion of tendons across a construction joint，The original design concept had been for in site concrete construction.Inspection and assessmentInspectionInspection work was undertaken in a number of phases and was linked with the testing required for the structure. The initial inspections recorded a number of visible problems including:Defective waterproofing on the exposed surface of the top flange.Water trapped in the internal space of the hollow box with depths up to 300 mm.Various drainage problems at joints and abutments.Longitudinal cracking of the exposed soffit of the central span.Longitudinal cracking on sides of the top flange of the pre-stressed sections.Widespread sapling on some in site concrete surfaces with exposed rusting reinforcement.AssessmentThe subject of an earlier paper, the objectives of the assessment were:Estimate the present load-carrying capacity.Identify any structural deficiencies in the original design.Determine reasons for existing problems identified by the inspection.Conclusion to the inspection and assessmentFollowing the inspection and the analytical assessment one major element of doubt still existed. This concerned the condition of the embedded pre-stressing wires, strands, cables or bars. For the purpose of structural analysis these elements、had been assumed to be sound. However, due to the very high forces involved,、a risk to the structure, caused by corrosion to these primary elements, was identified.The initial recommendations which completed the first phase of the assessment were:1. Carry out detailed material testing to determine the condition of hidden structural elements, in particularthe grouted post-tensioned steel cables.2. Conduct concrete durability tests.3. Undertake repairs to defective waterproofing and surface defects in concrete.Testing proceduresNon-destructi v e radar testingDuring the first phase investigation at a joint between pre-cast deck segments the observation of a void in a post-tensioned cable duct gave rise to serious concern about corrosion and the integrity of the pre-stress. However, the extent of this problem was extremely difficult to determine. The bridge contains 93 joints with an average of 24 cables passing through each joint, i.e. there were approx. 2200 positions where investigations could be carried out. A typical section through such a joint is that the 24 draped tendons within the spine did not give rise to concern because these were protected by in site concrete poured without joints after the cables had been stressed.As it was clearly impractical to consider physically exposing all tendon/joint intersections, radar was used to investigate a large numbers of tendons and hence locate duct voids within a modest timescale. It was fortunate that the corrugated steel ducts around the tendons were discontinuous through the joints which allowed theradar to detect the tendons and voids. The problem, however, was still highly complex due to the high density of other steel elements which could interfere with the radar signals and the fact that the area of interest was at most 102 mm wide and embedded between 150 mm and 800 mm deep in thick concrete slabs.Trial radar investigations.Three companies were invited to visit the bridge and conduct a trial investigation. One company decided not to proceed. The remaining two were given 2 weeks to mobilize, test and report. Their results were then compared with physical explorations.To make the comparisons, observation holes were drilled vertically downwards into the ducts at a selection of 10 locations which included several where voids were predicted and several where the ducts were predicted to be fully grouted. A 25-mm diameter hole was required in order to facilitate use of the chosen horoscope. The results from the University of Edinburgh yielded an accuracy of around 60%.Main radar sur v ey, horoscope verification of v oids.Having completed a radar survey of the total structure, a baroscopic was then used to investigate all predicted voids and in more than 60% of cases this gave a clear confirmation of the radar findings. In several other cases some evidence of honeycombing in the in site stitch concrete above the duct was found.When viewing voids through the baroscopic, however, it proved impossible to determine their actual size or how far they extended along the tendon ducts although they only appeared to occupy less than the top 25% of the duct diameter. Most of these voids, in fact, were smaller than the diameter of the flexible baroscopic being used (approximately 9 mm) and were seen between the horizontal top surface of the grout and the curved upper limit of the duct. In a very few cases the tops of the pre-stressing strands were visible above the grout but no sign of any trapped water was seen. It was not possible, using the baroscopic, to see whether those cables were corroded.Digital radar testingThe test method involved exciting the joints using radio frequency radar antenna: 1 GHz, 900 MHz and 500 MHz. The highest frequency gives the highest resolution but has shallow depth penetration in the concrete. The lowest frequency gives the greatest depth penetration but yields lower resolution.The data collected on the radar sweeps were recorded on a GSSI SIR System 10.This system involves radar pulsing and recording. The data from the antenna is transformed from an analogue signal to a digital signal using a 16-bit analogue digital converter giving a very high resolution for subsequent data processing. The data is displayed on site on a high-resolution color monitor. Following visual inspection it is then stored digitally on a 2.3-gigabyte tape for subsequent analysis and signal processing. The tape first of all records a ‘header’ noting the digital radar settings together with the trace number prior to recording the actual data. When the data is played back, one is able to clearly identify all the relevant settings —making for accurate and reliable data reproduction.At particular locations along the traces, the trace was marked using a marker switch on the recording unit or the antenna.All the digital records were subsequently downloaded at the University’s NDT laboratory on to a micro-computer.（The raw data prior to processing consumed 35 megabytes of digital data.）Post-processing was undertaken using sophisticated signal processing software. Techniques available for the analysis include changing the color transform and changing the scales from linear to a skewed distribution in order to highlight、突出certain features. Also, the color transforms could be changed to highlight phase changes. In addition to these color transform facilities, sophisticated horizontal and vertical filtering procedures are available. Using a large screen monitor it is possible to display in split screens the raw data and the transformed processed data. Thus one is able to get an accurate indication of the processing which has taken place. The computer screen displays the time domain calibrations of the reflected signals on the vertical axis.A further facility of the software was the ability to display the individual radar pulses as time domain wiggle plots. This was a particularly valuable feature when looking at individual records in the vicinity of the tendons.Interpretation of findingsA full analysis of findings is given elsewhere, Essentially the digitized radar plots were transformed to color line scans and where double phase shifts were identified in the joints, then voiding was diagnosed.Conclusions1. An outline of the bridge research platform in Europe is given.2. The use of impulse radar has contributed considerably to the level of confidence in the assessment of the Besses o’ th’ Barn Rail Bridge.3. The radar investigations revealed extensive voiding within the post-tensioned cable ducts. However, no sign of corrosion on the stressing wires had been found except for the very first investigation.欧洲桥梁研究欧洲联盟共同的研究平台诞生于欧洲联盟。
现浇楼板裂缝外文文献翻译中英文
外文文献翻译(含：英文原文及中文译文)英文原文Roduction and prevention and cure of the crack of skyscraperRothbard MAlong with the speeding of town house construction step, not a few areas with small residences set up one after another, many inhabitants move continuously into the new residence, their quality to housing request is more and more high, particularly pay attention to very much to some cracks circumstances which sprinkle building plank to appear now, worry these cracks' aring end will cause insecurity trouble, but in succession to building quality direct the section hurl tell.Such as once the some city develop a company to set up 6 layers of floor residence 16 totally, constructing area about 100,000 square meters, the brick mixs structure, the beginning repairs, one steps 2 box off with the brick wall, each one's establishing a turn of beam together building plank is togetherwhole to sprinkle, the plank thick 100 mms, concrete mark number is C20, house long about with 80-90 ms, don't establish flexible sew, first floor is the 2.2 m garage layer, the C20 reinforcing bar cage of the foundation adoption infuses to note a stake.It's small area's turn to complete work in October,2003, finishing construction acceptance, didn't discover obvious crack, discover the building plank appears crackwhen the inhabitant repair, past jointly to quality direct the section hurl tell, through step to see on the spot, 16 houses all exist the depth different crack.The crack width is between the 0.2 mms mms-0.4ses, the great majority of the crack position is placed in plank four Capes, the dynasty sun is more obvious.Hence, the Superintendent office of quality concerned, sinking to decline quantity and inclination degree to carry on a reexamination to the house first, result all in allow the scope, again look into construction diagram paper to also match to request concerning the norm.Owing to above-mentioned circumstance, pass by hard analytical, the confirmation crack reason has the following what time:1. cause now main reason of sprinkling the plank crack is the constringency of concrete, the concrete is in the nature the hardening the process, because water evaporates continuously, but the physical volume gradual constringency, but the plank is on all sides to be subjected to a stipulation of, can't flex freely, so when the constringency of concrete cause to sprinkle knothole stipulation now should the dint exceed certain limit, certanly will cause to sprinkle plank to open crack now.And the crack part take place much at should the dint more concentrated Cape in the place-plank, but is mutually perpendicular with the Overcast angle line of wall2. construct too early on the cast-in-place board , add and carry on one's shoulder or back the crack caused. " norm of inspection of qualityof structural construction of concrete " stipulates , before the concrete intensity reaches 1.2N/mm2, can't trample or install template and support on it . But developer , for race against time , catch up with progress , or concrete at , congeal and congeal stage after all for the first time still in water at the good cast-in-place board just, take up the post of purpose to trample, carry the material , concentrate on piling up fragment of brick , mortar , template ,etc.. Premature adding and is carried on one's shoulder or back, has caused the crack of cast-in-place board artificially.3. the crack which the temperature change causes. As everybody knows, the cement condenses and hardens fast at room temperature, the characteristic such as being great of heat of hydration, especially in summer, after the concrete is built, the release amount of the heat of hydration is great, the concrete is under the high temperature, can't get and water maintenance in time , and desiccate and shrink, make concrete take place dry to split , result in fracturing finally. Investigation find in the majority board corner crack in , tan by the sun towards the front directly the sun.4.the house is crossed too long to set up the essential expansion joint , is the reason which causes the crack too. The developer is in order to save the land, often take the length of the house into account , make the house whole too long, set up expansion joint either, because of lack essential expansion joint, freedom flexible degree in house reach orexceed should set up interval that expansion joint require , will present the crack too.5.the board is defeated by the muscle and sunk in the crack produced . In the course of constructing, because constructors operate barbarously, trample the reinforcing bar arbitrarily , cause and shoulder the muscle and sink, the antiabrasion layer is too big, reduce the sectional effective height of the board, make the bearing capacity of the board unable to reach the requirement of ones that design, thus cause the production of the crack of board.Effective height, make the bearing capacity of the board unable to reach the requirement of ones that design, thus cause the production of the crack of board. How to prevent and cure the production of the board crack of cast-in-place board, according to the construction experience for many years, offer some following prevention measures, suitable for consulting :1. Do well cast-in-place board maintain , work , guarantee concrete intensity , prevent and cure important link that crack produce one of conscientiously. The norm stipulates , must cover and keep maintenance warm in 12 hours after the concrete is built at room temperature, ordinary cement is no less than 7 days, if the one that ignored to concrete watered maintenance, on one hand it reduce concrete intensity, on the other hand it make concrete to be in the course of hardening too late to supplementthe moisture, therefore lack water and produce the crack in a large amount. So do a good job of watering maintenance of concrete , can already reduce the crack that temperature produces , can also reduce the crack that the concrete shrink and produce . 2. cast-in-place board don't pass morning people , pile material , He Shi load , because concrete have a sclerosis course build ,, just have intensity; In this course , should maintain the concrete , can't exert any external force to the concrete . In a situation that the concrete has not had certain intensity yet , concentrate on , pile up construction material or prop up mould stand , rest on it, that brought the cast-in-place board is not intensity like this, but more cracks. So, must make sure that just allow to trample or install template and support on it after the concrete intensity reaches 1.2N/mm2.3. shoulder thickness of antiabrasion layer of the muscle the strict control panel . Cast-in-place board shoulder muscle put , on board , have roof beam according to designing requirement through generally put on reinforcing bar of roof beam or stay with reinforcing bar lashing of roof beam cut off , For control good to shoulder muscle antiabrasion layer thickness , must adopt φ10 - φ14 reinforcing bar horse stool, vertical-horizontal interval 800mm come fixed position to shoulder muscle from side to side, and with electric welding horse with shoulder muscle weld firm stool, make horse to be stool while the concrete builds non-wiping, guarantee , shoulder muscle sink, control , shoulder musclethickness of antiabrasion layer effectively , make board shoulder muscle antiabrasion layer cross thick producing cracking.4. control good sand , stone in a foot-path and mud content strictly. The thick sand in the cast-in-place board should be selected for use, a stone of foot-path between 0.25-0.5mm, the mud content of grit can't exceed 1% . Sand,, stone grains of foot-path careful and too light, mud content too big, will reduce concrete intensity, will make the concrete produce the crack finally.5. dispose certain amounts of angle muscles in four corners of the board , radiate the muscle . Take place in board corner phenomenon this more to cast-in-place board crack, corner set up all around in boardThe length radiates the muscle for about 1800mm, so as to meet demands of angle stress of the board, the stress sphere of action of making the cast-in-place board produce the crack conforms with radiation muscle, thus change and control the production of the crack effectively forced concrete structure reinforced with an overview ReinSince the reform and opening up, with the national economy's rapid and sustained development of a reinforced concrete structure built, reinforced with the development of technology has been great. Therefore, to promote the use of advanced technology reinforced connecting to improve project quality and speed up the pace of construction, improve labor productivity, reduce costs, and is of great significance.Reinforced steel bars connecting technologies can be divided into two broad categories linking welding machinery and steel. There are six types of welding steel welding methods, and some apply to the prefabricated plant, and some apply to the construction site, some of both apply. There are three types of machinery commonly used reinforcement linking method primarily applicable to the construction site. Ways has its own characteristics and different application, and in the continuous development and improvement. In actual production, should be based on specific conditions of work, working environment and technical requirements, the choice of suitable methods to achieve the best overall efficiency.radial squeeze linkWill be a steel sleeve in two sets to the highly-reinforced Department with superhigh pressure hydraulic equipment (squeeze tongs) along steel sleeve radial squeeze steel casing, in squeezing out tongs squeeze pressure role of a steel sleeve plasticity deformation closely integrated with reinforced through reinforced steel sleeve and Wang Liang's Position will be two solid steel bars linkedCharacteristic: Connect intensity to be high, performance reliable, can bear high stress draw and pigeonhole the load and tired load repeatedly.Easy and simple to handle, construction fast, save energy andmaterial, comprehensive economy profitable, this method has been already a large amount of application in the project.Applicable scope : Suitable for Ⅱ, Ⅲ, Ⅳgrade reinforcing bar (including welding bad reinforcing bar ) with ribbing of φ18- 50mm, connection between the same diameter or different diameters reinforcing bar .must squeeze linkExtruders used in the covers, reinforced axis along the cold metal sleeve squeeze dedicated to insert sleeve Lane two hot rolling steel drums into a highly integrated mechanical linking methods.Characteristic: Easy to operate and joining fast and not having flame homework , can construct for 24 hours , save a large number of reinforcing bars and energy.Applicable scope : Suitable for , set up according to first and second class antidetonation requirement -proof armored concrete structure φⅡ, Ⅲgrade reinforcing bar with ribbing of hot rolling of 20- 32mm join and construct live.cone thread connectingUsing cone thread to bear pulled, pressed both effort and self-locking nature, undergo good principles will be reinforced by linking into cone-processing thread at the moment the value of integration into the joints connecting steel bars.Characteristic: Simple , all right preparatory cut of the craft , connecting fast, concentricity is good, have pattern person who restrain from advantage reinforcing bar carbon content.Applicable scope : Suitable for the concrete structure of the industry , civil building and general structures, reinforcing bar diameter is for for the the 16- 40mm one Ⅱ, Ⅲgrade verticality, it is the oblique to or reinforcing bars horizontal join construct live.These are now commonly used to connect steel synthesis methods, which links technology in the United States, Britain, Japan and other countries are widely used. There are different ways to connect their different characteristics and scope of the actual construction of production depending on the specific project choose a suitable method of connecting to achieve both energy conservation and saving time limit for a project ends.Causes of cracks in concrete and control measuresShrinkage cracksShrinkage cracks are caused by the humidity, it accounts for non-structural cracks in concrete in the main part. We know that concrete is a cement as the main cementing material to natural sand, stone aggregate mixing water, after casting molding, hardens and the formation of artificial stone.In the construction, in order to ensure its workability, often adding cement hydration than water needed for 4 to 5 times more water. More of these water to free state exists, and the gradualevaporation of the hardening process, resulting in the formation of large pores inside the concrete, voids or holes, resulting in volume shrinkage of concrete. In addition, the hardening process of concrete hydration and carbonation of concrete volume will lead to shrinkage. According to the experimental determination of the ultimate shrinkage of concrete is about 0104% ~ 0106%.Shows that shrinkage is the inherent physical properties of concrete, in general, the larger water-cement ratio, the higher the concrete strength, aggregate less, the higher the temperature, surface water loss is larger, the larger the value of its contract, the more easily shrinkage cracks. According to the formation of shrinkage cracks and formation mechanism of the time, works in the common shrinkage cracks are mainly plastic shrinkage cracks, settlement shrinkage cracking and drying shrinkage cracks in three categories, in addition to their contract (chemical shrinkage) cracks and carbonation shrinkage cracks.Plastic shrinkage cracks Plastic shrinkage cracks in concrete plastic stage, before the final set. The cause of this is concrete paste and quickly evaporating water flow to the surface, with the increase in water loss, capillary negative pressure generated by contraction of the concrete surface of the drastic volume shrinkage. Strength of concrete at a time has not yet formed, which resulted in cracking of the concrete surface.This multi-cracks in dry weather, hot and windy, the fracture shallow, intermediate width, both ends of the fine, of different lengths, anddisconnected.中文译文现浇楼板裂缝的产生与防治Rothbard M随着城镇住宅建设步伐的加快，不少小区居住区相继成立，不少居民不断迁入新居，其对住房要求的质量越来越高，尤其是要重视现在一些散落的建筑板出现裂缝的情况，担心这些裂缝的坍塌会造成不安全的麻烦，但相继对建筑质量直接段投诉。
外文翻译混凝土裂缝的成因预防及处理
The causes, prevention and treatment of cracks in concrete Abstract:In the building construction concrete cracks a quality common problem, the causes of cracks in concrete, prior prevention, as well as after the repair process is a more common phenomenon in the process of building production, should be taken seriously enough. The concrete is a brittle material of a gravel aggregate, cement, water and other additional material formed by mixing a non-homogeneous. Concrete construction and deformation constraints and a series of problems, there are a large number of micro-porosity, cavitation and micro-cracks in the concrete hardening molding. The author combines his engineering work experience, summed up the cracks in concrete causes and prevention measures.Keywords: causes of cracks in concrete preventive treatmentIn building construction, concrete cracks is a widespread problem, cracks solution is a more difficult problem. Cracks in concrete reasons are manifold, deformation: such as contraction, expansion, settlement and other causes cracks; external load caused by: improper maintenance of concrete; cracks caused by the external additive problems.Concrete cracks, if not prevention measures to solve, extending its further development will lead to the internal reinforcement corrosive, reducing the carrying capacity of the reinforced concrete structure, impermeability, durability useful life, and even affect people's lives and property safety . Crack is impossible to completely eliminate the engineering specification expressly provides some structure in which the different conditions, allowing the existence of a certain width and depth of the crack. But in the construction process should be as far as possible to take effective preventive and technical safeguards to effectively control the cracks, as little as possible or minimize crack width, depth, and in particular to avoid in key positions or harmful cracks.1.Causes and types of concrete cracksThe concrete is a brittle material of a gravel aggregate, cement, water and other additional material formed by mixing a non-homogeneous. Hardening molding concrete concrete construction and deformation constraints there are a large number of micro-porosity, cavitation and micro-cracks, precisely because of the existence of these initial defects before the concrete showing some heterogeneity characteristics . Micro-cracks is usually a harmless cracks on concrete load-bearing, seepage and use the function does not cause harm. But in the concrete under load, temperature effects, the micro-cracks will continue to expand and connectivity, and ultimately the formation of visible macro cracks, the cracks is often said that the concrete works.Many cracks in concrete cracks caused by deformation: such as temperature change, shrinkage, expansion, uneven subsidence caused cracks; external load induced cracks; cracks caused by improper conservation of the environment and chemical action, etc. .Common cracks in the concrete are the following: (1) shrinkage cracks; ②plastic shrinkage cracking; (3) settlement cracks; ④temperature cracks; ⑤chemical reaction caused by cracks.2.Concrete cracks and prevention2.1 Shrinkage cracks and prevention ofShrinkage cracks appear in a week or so after the end of the concrete curing period of time or after concrete pouring. The evaporation of the water in the slurry will produce shrinkage, and the shrinkage is irreversible. Drying shrinkage cracks are mainly caused due to the different degree of evaporation of the moisture inside and outside the concrete result of deformation of the type: concrete affected by the influence of external conditions, excessive surface moisture loss, large deformation, internal humidity changes smaller deformation smaller, the larger the surface shrinkage deformation by concrete internal constraints, have a greater tensile stress cracks. The lower the relative humidity, the greater the shrinkage of cement paste shrinkage cracks are easy to produce. Shrinkage cracks parallel to the surface of the linear or reticular light fine cracks, width of more than 0.05 to 0.2 mm between the flat parts more common in mass concrete, thin flat-slab along the short to distribution. Shrinkage cracks usually affect the impermeability of concrete, causing corrosion of steel affect the durability of concrete, water pressure will produce hydraulic fracturing affecting concrete bearing capacity. The concrete shrinkage main and to the water-cement ratio of the concrete, cement component, the amount of cement used, thenature and amount of aggregate, the amount of admixture.The main preventive measures:(1)Selection of a smaller amount of shrinkage cement, commonly used in low heat cement and fly ash cement, reduce the amount of cement.(2)Concrete shrinkage by water-cement ratio, the greater the water-cement ratio, the greater the shrinkage in the concrete mix design should try to control the selection of a good water-cement ratio, while mixing the water-reducing agent .(3)Strict control than with concrete mixing and construction, concrete water consumption must not be greater than the amount of water given by the mixture ratio design.(4)To strengthen the early curing of concrete and appropriate to extend the concrete curing time. Appropriate to extend the winter construction concrete insulation cover, and brushing curing agent curing.(5) Set the appropriate contraction joints in concrete structures2.2 Plastic shrinkage cracks and preventionThe plastic shrinkage refers to the before condensation, the concrete surface due to rapid dehydration resulting contraction. Plastic shrinkage cracking is generally hot and dry or windy weather, the cracks mostly wide in the middle, both ends of the thin and vary in length, non-coherentstate. Short cracks as long as 20 to 30cm the longer cracks of up to 2 to 3 m, width of 1 to 5 mm. Main causes: the concrete before the final setting almost no strength or intensity is very small or just the final setting concrete small strength, high temperature or a larger wind, the concrete surface excessive water loss, resulting in capillary have a greater negative pressure of the concrete volume of a sharp contraction, but this time the strength of the concrete can not resist its own contraction, resulting in cracking. The main factors affecting the plastic shrinkage cracking water-cement ratio, the setting time of the concrete, the ambient temperature, wind speed, relative humidity, and so on.The main preventive measures:(1) Selection of shrinkage values smaller high early strength Portland cement or ordinary Portland cement.(2) Strict control of water-cement ratio, to increase the slump and workability of the concrete, to reduce the amount of cement and water mixed with superplasticizer.(3) Pouring concrete before watering the grass roots and templates evenly soaked.(4) Timely covered by plastic film or wet straw, hemp sheet to maintain final setting of concrete the moist front surface or the surface of the concrete spraying curing agent for conservation.To set the sun and wind facilities .(5) At high temperatures and windy weather, timely conservation.2.3 subsidence cracks and preventionSubsidence cracks caused by structural foundation soil is uneven, soft, or backfill or flooding due to uneven settlement; template stiffness, the template support spacing is too large or the bottom of the support as a result of loose, especially in the template support winter on the frozen ground, permafrost thaw uneven settlement, resulting in the concrete structure cracks. Such cracks are deep into or through the cracks, toward subsidence, generally along the perpendicular to the ground or in the form of an angle of 30 °to 45 °direction, subsidence cracks tend to have a certain amount of dislocation, crack width is often and is proportional to the amount of the settlement. Crack width was less affected by temperature changes. Ground deformation stability, subsidence cracks basically stabilized.The main preventive measures:(1)on the soft soil, filling foundation should be carried out prior to the construction of the superstructure necessary compaction and reinforcement.(2)to ensure that the template has a sufficient strength and stiffness, and firmly support the foundation uniform force.(3) prevent the process of concreting the foundation is immersed inwater.(4) template removal time can not be too early, and pay attention to the order form removal.(5) in the erection of the template on the permafrost to take certain precautions.2.4 Temperature cracks and preventionTemperature cracks occurred in mass concrete surface or larger changes in temperature regions in concrete structures. Concrete pouring, in the hardening process of cement hydration reaction to produce large amounts of heat of hydration (when the amount of cement per cubic meter of concrete will release 17,500 27500kJ heat at 350 to 550 kg/m3, so that the internal temperature of the concrete SITA about 70 °C or higher). Cause the internal temperature to rise sharply due to the larger volume of concrete, the accumulation of a large amount of heat of hydration within the concrete and easy to distribute, and rapid cooling of the surface of the concrete, thus forming a larger temperature difference inside and outside, the larger the temperature difference caused by the internal and external different degrees of thermal expansion and contraction of the concrete surface tensile stress (Practice has proved that when the temperature difference between inside and outside of the concrete itself is 25 ° C to 26 °C, will produce roughly about10MPa concrete tensile stress). When the tensile stress exceeds the ultimate tensile strength of the concrete, the concrete surface cracks, cracks occurred in the concrete construction in the late. Concrete construction when the temperature changes, or concrete attacked by the cold wave will lead to concrete surface temperature sharp decline, and contraction, contraction of the concrete surface bound by internal concrete, will produce large tensile stress. cracks, such cracks are generated in the the shallow concrete surface within the range of usually only.The trend of temperature cracks usually certain rules, often criss-cross a large area of structural cracks; the length of the beam and plate size larger structures, cracks parallel to the short side; deep and penetrating temperature cracks are generally parallel or nearly parallel to the direction of the short side , cracks along the longest edge segments appear more dense middle. Crack width sizes, affected by temperature changes more obvious, summer, winter wide narrow. The high temperature expansion caused by the concrete temperature is usually middle coarse fine at both ends, while the the shrink cracks thickness less obvious changes. The emergence of such cracks can cause corrosion of steel, concrete carbonation, reduce freeze-thaw resistance of concrete, anti-fatigue and impermeability.The main preventive measures:(1) try to use low heat or moderate heat cement, slag cement, fly ash cement.(2) reduce the amount of cement to try to control the amount of cement 450kg/m3.(3) reduce the water-cement ratio, generally water-cement ratio of concrete is controlled below 0.6.(4) improve the aggregate gradation, fly ash or superplasticizer to reduce the amount of cement, lower heat of hydration.(5) improve the concrete mixing process, "secondary air" traditional "cold" on the basis of new technology, reduce the temperature of concrete pouring.(6)a certain amount of concrete admixture having less water, plasticizers, retarding admixture role to improve the fluidity of the concrete mixture, water retention, reduce the heat of hydration, delaying the time of occurrence of the thermal peak.(7)hot season puts up visor and other auxiliary measures to control the temperature rise of the concrete pouring, to reduce pouring concrete temperature.(8)mass concrete temperature stress associated with the structure size, the larger the size of the concrete structure, the greater the temperature stress, so reasonable arrangements for the construction process, hierarchical, block pouring, to facilitate cooling, reducingconstraints.2.5 chemical reaction caused cracks and preventionAlkali-aggregate reaction cracks and steel corrosion cracks caused by the most common due to the chemical reaction caused by cracks in the reinforced concrete structure. Concrete mixing will produce some of the alkaline ions, these ions produce a chemical reaction with certain reactive aggregate and absorbs water in the surrounding environment and the volume increases, resulting in concrete crisp, expansion cracking. Such cracks usually appear in the concrete structure during use, in the event difficult to remedy, should take effective measures to prevent it in the construction. Concrete pouring poor vibrators or reinforced protective layer is thin, harmful substances into the concrete reinforcing bars from corrosion, the corroded reinforcement volume expansion, leading to concrete Splitting the cracks of this type of longitudinal cracks along the location of reinforcement .The main preventive measures:(1) selection of the alkali reactivity of small sand and gravel aggregate.(2) selection of low-alkali cement and admixtures of low-alkali or alkali.(3) selection of a suitable admixture AAR with.3 crack treatmentCracks in concrete remedial measures mainly the following methods: surface repair method, grouting, caulking closure method, structural reinforcement, concrete replacement method, electrochemical protection and legal bionic self-healing.3.1 Surface repair methodSurface repair method is a simple, common repair method, the action is in the cracks in the surface of the painting grout, epoxy mortar or concrete surface coating paint, anti-corrosion materials such as asphalt, concrete protection at the same time in order to prevent various The Effect of cracking, usually can paste in cracks in the surface of the glass fiber cloth and other measures.3.2 grouting, caulking closure methodThe grouting method is the use of pressure equipment cementing material is pressed into the cracks in the concrete, the cementing material hardened concrete to form a whole, and thus play the purpose of plugging consolidation. Top cementing material grout, epoxy, methacrylate, polyurethane and other chemical materials. The filleting gouges along the cracks in the tank filled, the plastic or rigid sealing material, in order to achieve the purpose of closed cracks. Commonly used plastic materialsare PVC, clay, plastic ointment, butyl rubber, etc.; rigid sealing material is a polymer cement mortar.3.3 Structural reinforcement methodWhen the the cracks impact on the performance of concrete structures, to take structural reinforcement concrete structure. Commonly used in the following ways: structural reinforcement to increase the cross-sectional area of the concrete structure, corner in the component outsourcing steel, prestressed Reinforcing paste the steel reinforcement, additional the fulcrum reinforcement and shotcrete reinforcement.3.4 Concrete replacement methodThe concrete substitution method is an effective method for dealing with serious damage to the concrete, this method is deteriorated concrete is removed first, and then replaced into the new concrete or other materials. Top replacement materials: of Ordinary concrete or cement mortar, polymer or polymer modified concrete or mortar.3.5 electrochemical Protection ActCathodic protection, chloride extraction, alkaline recovery method, the use of the electrochemical action of the applied electric field in the medium, to change concrete or reinforced concrete in which the state of the environment, passivated steel, in order to achieve the purpose ofanti-corrosion.3.6 biomimetic self-healing legalBionic self-healing legitimate the traditional components of the concrete in some special components such as liquid-core fibers or capsules containing binder, formed within the concrete the intelligent bionic self-healing neural network system, when the concrete cracks secreted part of the liquid core fiber cracks can heal again. Conclusion:Cracks is a common phenomenon in the concrete structure, its appearance will not only reduce the impermeability of the building, affect the use of the building, and would lead to corrosion of steel, concrete carbonation, reduce the durability of the materials, the impact the carrying capacity of the building, so to carefully study the concrete cracks, be treated differently, using a reasonable method for processing to take effective preventive measures to prevent the emergence and development of cracks in the construction, to ensure the safety of buildings and structures and stable work.混凝土裂缝的成因、预防及处理摘要：在建筑工程施工中混凝土裂缝的产生是一项质量通病，因此对混凝土裂缝的成因分析、事先预防，以及产生后的修补处理是建筑生产过程中较为普遍的现象，应引起足够的重视。
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中英文对照外文翻译文献中英文资料对照外文翻译附录A桥梁裂缝产生原因浅析近年来，我省交通基础建设得到迅猛发展，各地兴建了大量的混凝土桥梁。
在桥梁建造和使用过程中，有关因出现裂缝而影响工程质量甚至导桥梁垮塌的报道屡见不鲜。
混凝土开裂可以说是“常发病”和“多发病”，经常困扰着桥梁工程技术人员。
其实，如果采取一定的设计和施工措施，很多裂缝是可以克服和控制的。
为了进一步加强对混凝土桥梁裂缝的认识，尽量避免工程中出现危害较大的裂缝，本文尽可能对混凝土桥梁裂缝的种类和产生的原因作较全面的分析、总结，以方便设计、施工找出控制裂缝的可行办法，达到防范于未然的作用。
混凝土桥梁裂缝种类、成因实际上，混凝土结构裂缝的成因复杂而繁多，甚至多种因素相互影响，但每一条裂缝均有其产生的一种或几种主要原因。
混凝土桥梁裂缝的种类，就其产生的原因，大致可划分如下几种：1.荷载引起的裂缝混凝土桥梁在常规静、动荷载及次应力下产生的裂缝称荷载裂缝，归纳起来主要有直接应力裂缝、次应力裂缝两种。
直接应力裂缝是指外荷载引起的直接应力产生的裂缝。
裂缝产生的原因有：1.设计计算阶段，结构计算时不计算或部分漏算；计算模型不合理；结构受力假设与实际受力不符；荷载少算或漏算；内力与配筋计算错误；结构安全系数不够。
结构设计时不考虑施工的可能性；设计断面不足；钢筋设置偏少或布置错误；结构刚度不足；构造处理不当；设计图纸交代不清等。
2.施工阶段，不加限制地堆放施工机具、材料；不了解预制结构结构受力特点，随意翻身、起吊、运输、安装；不按设计图纸施工，擅自更改结构施工顺序，改变结构受力模式；不对结构做机器振动下的疲劳强度验算等。
3.使用阶段，超出设计载荷的重型车辆过桥；受车辆、船舶的接触、撞击；发生大风、大雪、地震、爆炸等。
次应力裂缝是指由外荷载引起的次生应力产生裂缝。
裂缝产生的原因有：1.在设计外荷载作用下，由于结构物的实际工作状态同常规计算有出入或计算不考虑，从而在某些部位引起次应力导致结构开裂。
例如两铰拱桥拱脚设计时常采用布置“X”形钢筋、同时削减该处断面尺寸的办法设计铰，理论计算该处不会存在弯矩，但实际该铰仍然能够抗弯，以至出现裂缝而导致钢筋锈蚀。
2.桥梁结构中经常需要凿槽、开洞、设置牛腿等，在常规计算中难以用准确的图式进行模拟计算，一般根据经验设置受力钢筋。
研究表明，受力构件挖孔后，力流将产生绕射现象，在孔洞附近密集，产生巨大的应力集中。
在长跨预应力连续梁中，经常在跨内根据截面内力需要截断钢束，设置锚头，而在锚固断面附近经常可以看到裂缝。
因此，若处理不当，在这些结构的转角处或构件形状突变处、受力钢筋截断处容易出现裂缝。
实际工程中，次应力裂缝是产生荷载裂缝的最常见原因。
次应力裂缝多属张拉、劈裂、剪切性质。
次应力裂缝也是由荷载引起，仅是按常规一般不计算，但随着现代计算手段的不断完善，次应力裂缝也是可以做到合理验算的。
例如现在对预应力、徐变等产生的二次应力，不少平面杆系有限元程序均可正确计算，但在40年前却比较困难。
在设计上，应注意避免结构突变（或断面突变），当不能回避时，应做局部处理，如转角处做圆角，突变处做成渐变过渡，同时加强构造配筋，转角处增配斜向钢筋，对于较大孔洞有条件时可在周边设置护边角钢。
荷载裂缝特征依荷载不同而异呈现不同的特点。
这类裂缝多出现在受拉区、受剪区或振动严重部位。
但必须指出，如果受压区出现起皮或有沿受压方向的短裂缝，往往是结构达到承载力极限的标志，是结构破坏的前兆，其原因往往是截面尺寸偏小。
根据结构不同受力方式，产生的裂缝特征如下：1.中心受拉。
裂缝贯穿构件横截面，间距大体相等，且垂直于受力方向。
采用螺纹钢筋时，裂缝之间出现位于钢筋附近的次裂缝。
2.中心受压。
沿构件出现平行于受力方向的短而密的平行裂缝。
3.受弯。
弯矩最大截面附近从受拉区边沿开始出现与受拉方向垂直的裂缝，并逐渐向中和轴方向发展。
采用螺纹钢筋时，裂缝间可见较短的次裂缝。
当结构配筋较少时，裂缝少而宽，结构可能发生脆性破坏。
4.大偏心受压。
大偏心受压和受拉区配筋较少的小偏心受压构件，类似于受弯构件。
中英文对照外文翻译文献5.小偏心受压。
小偏心受压和受拉区配筋较多的大偏心受压构件，类似于中心受压构件。
6.受剪。
当箍筋太密时发生斜压破坏，沿梁端腹部出现大于45°方向的斜裂缝；当箍筋适当时发生剪压破坏，沿梁端中下部出现约45°方向相互平行的斜裂缝。
7.受扭。
构件一侧腹部先出现多条约45°方向斜裂缝，并向相邻面以螺旋方向展开。
8.受冲切。
沿柱头板内四侧发生约45°方向斜面拉裂，形成冲切面。
9.局部受压。
在局部受压区出现与压力方向大致平行的多条短裂缝。
2.温度变化引起的裂缝混凝土具有热胀冷缩性质，当外部环境或结构内部温度发生变化，混凝土将发生变形，若变形遭到约束，则在结构内将产生应力，当应力超过混凝土抗拉强度时即产生温度裂缝。
在某些大跨径桥梁中，温度应力可以达到甚至超出活载应力。
温度裂缝区别其它裂缝最主要特征是将随温度变化而扩张或合拢。
引起温度变化主要因素有：1.年温差。
一年中四季温度不断变化，但变化相对缓慢，对桥梁结构的影响主要是导致桥梁的纵向位移，一般可通过桥面伸缩缝、支座位移或设置柔性墩等构造措施相协调，只有结构的位移受到限制时才会引起温度裂缝，例如拱桥、刚架桥等。
我国年温差一般以一月和七月月平均温度的作为变化幅度。
考虑到混凝土的蠕变特性，年温差内力计算时混凝土弹性模量应考虑折减。
2.日照。
桥面板、主梁或桥墩侧面受太阳曝晒后，温度明显高于其它部位，温度梯度呈非线形分布。
由于受到自身约束作用，导致局部拉应力较大，出现裂缝。
日照和下述骤然降温是导致结构温度裂缝的最常见原因。
3.骤然降温。
突降大雨、冷空气侵袭、日落等可导致结构外表面温度突然下降，但因内部温度变化相对较慢而产生温度梯度。
日照和骤然降温内力计算时可采用设计规范或参考实桥资料进行，混凝土弹性模量不考虑折减。
4.水化热。
出现在施工过程中，大体积混凝土（厚度超过2.0米）浇筑之后由于水泥水化放热，致使内部温度很高，内外温差太大，致使表面出现裂缝。
施工中应根据实际情况，尽量选择水化热低的水泥品种，限制水泥单位用量，减少骨料入模温度，降低内外温差，并缓慢降温，必要时可采用循环冷却系统进行内部散热，或采用薄层连续浇筑以加快散热。
5.蒸汽养护或冬季施工时施工措施不当，混凝土骤冷骤热，内外温度不均，易出现裂缝。
6.预制T梁之间横隔板安装时，支座预埋钢板与调平钢板焊接时，若焊接措施不当，铁件附近混凝土容易烧伤开裂。
采用电热张拉法张拉预应力构件时，预应力钢材温度可升高至350℃，混凝土构件也容易开裂。
试验研究表明，由火灾等原因引起高温烧伤的混凝土强度随温度的升高而明显降低，钢筋与混凝土的粘结力随之下降，混凝土温度达到300℃后抗拉强度下降50%，抗压强度下降60%，光圆钢筋与混凝土的粘结力下降80%；由于受热，混凝土体内游离水大量蒸发也可产生急剧收缩。
3.收缩引起的裂缝在实际工程中，混凝土因收缩所引起的裂缝是最常见的。
在混凝土收缩种类中，塑性收缩和缩水收缩（干缩）是发生混凝土体积变形的主要原因，另外还有自生收缩和炭化收缩。
塑性收缩。
发生在施工过程中、混凝土浇筑后4-5小时左右，此时水泥水化反应激烈，分子链逐渐形成，出现泌水和水分急剧蒸发，混凝土失水收缩，同时骨料因自重下沉，因此时混凝土尚未硬化，称为塑性收缩。
塑性收缩所产生量级很大，可达1%左右。
在骨料下沉过程中若受到钢筋阻挡，便形成沿钢筋方向的裂缝。
在构件竖向变截面处如T梁、箱梁腹板与顶底板交接处，因硬化前沉实不均匀将发生表面的顺腹板方向裂缝。
为减小混凝土塑性收缩，施工时应控制水灰比，避免过长时间的搅拌，下料不宜太快，振捣要密实，竖向变截面处宜分层浇筑。
缩水收缩（干缩）。
混凝土结硬以后，随着表层水分逐步蒸发，湿度逐步降低，混凝土体积减小，称为缩水收缩（干缩）。
因混凝土表层水分损失快，内部损失慢，因此产生表面收缩大、内部收缩小的不均匀收缩，表面收缩变形受到内部混凝土的约束，致使表面混凝土承受拉力，当表面混凝土承受拉力超过其抗拉强度时，便产生收缩裂缝。
混凝土硬化后收缩主要就是缩水收缩。
如配筋率较大的构件（超过3%），钢筋对混凝土收缩的约束比较明显，混凝土表面容易出现龟裂裂纹。
自生收缩。
自生收缩是混凝土在硬化过程中，水泥与水发生水化反应，这种收缩与外界湿度无关，且可以是正的（即收缩，如普通硅酸盐水泥混凝土），也可以是负的（即膨胀，如矿渣水泥混凝土与粉煤灰水泥混凝土）。
炭化收缩。
大气中的二氧化碳与水泥的水化物发生化学反应引起的收缩变形。
炭化收缩只有在湿度50%左右才能发生，且随二氧化碳的浓度的增加而加快。
炭化收缩一中英文对照外文翻译文献般不做计算。
混凝土收缩裂缝的特点是大部分属表面裂缝，裂缝宽度较细，且纵横交错，成龟裂状，形状没有任何规律。
研究表明，影响混凝土收缩裂缝的主要因素有：1.水泥品种、标号及用量。
矿渣水泥、快硬水泥、低热水泥混凝土收缩性较高，普通水泥、火山灰水泥、矾土水泥混凝土收缩性较低。
另外水泥标号越低、单位体积用量越大、磨细度越大，则混凝土收缩越大，且发生收缩时间越长。
例如，为了提高混凝土的强度，施工时经常采用强行增加水泥用量的做法，结果收缩应力明显加大。
2.骨料品种。
骨料中石英、石灰岩、白云岩、花岗岩、长石等吸水率较小、收缩性较低；而砂岩、板岩、角闪岩等吸水率较大、收缩性较高。
另外骨料粒径大收缩小，含水量大收缩越大。
3.水灰比。
用水量越大，水灰比越高，混凝土收缩越大。
4.外掺剂。
外掺剂保水性越好，则混凝土收缩越小。
5.养护方法。
良好的养护可加速混凝土的水化反应，获得较高的混凝土强度。
养护时保持湿度越高、气温越低、养护时间越长，则混凝土收缩越小。
蒸汽养护方式比自然养护方式混凝土收缩要小。
6.外界环境。
大气中湿度小、空气干燥、温度高、风速大，则混凝土水分蒸发快，混凝土收缩越快。
7.振捣方式及时间。
机械振捣方式比手工捣固方式混凝土收缩性要小。
振捣时间应根据机械性能决定，一般以5-15s/次为宜。
时间太短，振捣不密实，形成混凝土强度不足或不均匀；时间太长，造成分层，粗骨料沉入底层，细骨料留在上层，强度不均匀，上层易发生收缩裂缝。
对于温度和收缩引起的裂缝，增配构造钢筋可明显提高混凝土的抗裂性，尤其是薄壁结（壁厚20-60cm）。
构造上配筋宜优先采用小直径钢筋(φ8-φ14)、小间距布置(@10-@15cm)，全截面构造配筋率不宜低于0.3%，一般可采用0.3%~0.5%。
4.地基础变形引起的裂缝由于基础竖向不均匀沉降或水平方向位移，使结构中产生附加应力，超出混凝土结构的抗拉能力，导致结构开裂。
基础不均匀沉降的主要原因有：1.地质勘察精度不够、试验资料不准。