土木工程专业英语全部惠宽堂

Lesson 1Compression MembersNew Words1. achieve achievement2. eccentricity center, 中心; ec centric 偏心的；ec centricity 偏心，偏心距3. inevitable evitable 可避免的avoidable; in evitable 不可避免的unavoidable4. truss 桁架triangular truss, roof truss, truss bridge5. bracing brace 支柱，支撑；bracing, 支撑，撑杆6. slender 细长，苗条；stout; slenderness7. buckle 压曲，屈曲；buckling load8. stocky stout9. convincingly convince, convincing, convincingly10. stub 树桩，短而粗的东西；stub column 短柱11. curvature 曲率；curve, curvature12. detractor detract draw or take away; divert; belittle，贬低，诽谤；13. convince14. argument dispute, debate, quarrel, reason, 论据（理由）15. crookedness crook 钩状物，v弯曲，crooked 弯曲的16. provision 规定，条款Phrases and Expressions1. compression member2. bending moment shear force, axial force3. call upon (on) 要求，请求，需要4. critical buckling load 临界屈曲荷载critical 关键的，临界的5. cross-sectional area6. radius of gyration 回转半径gyration7. slenderness ratio 长细比8. tangent modulus 切线模量9. stub column 短柱10. trial-and-error approach 试算法11. empirical formula 经验公式empirical 经验的12. residual stress 残余应力residual13. hot-rolled shape 热轧型钢hot-rolled bar14. lower bound 下限upper bound 上限16. effective length 计算长度Definition （定义）Compression members are those structural elements that are subjected only to axial compressive forces: that is, the loads are applied along a longitudinal axis through the centroid of the member cross section, and the stress can be taken as f a=P/A, where f a is considered to be uniform over the entire cross section. 受压构件是仅受轴向压力作用的构件，即：荷载是沿纵轴加在其截面形心上的，其应力可表示为…，式中，假定f a在整个截面上均匀分布。

This ideal state is never achieved in reality, however, and some eccentricity of the load is inevitable. 然而，现实中从来都不可能达到这种理想状态，因为荷载的一些偏心是不可避免的。

This will result in bending, but it can usually be regarded as secondary and can be neglected if the theoretical loading condition is closely approximated. 这将导致弯曲，但通常认为它是次要的，如果理论工况是足够近似的，就可将其忽略。

This cannot always be done if there is a computed bending moment, and situation of this type will be considered in Beam-Columns. 但这并非总是可行的，如有计算出的弯矩存在时，这种情形将在梁柱理论中加以考虑。

The most common type of compression member occurring in buildings and bridges is the column, a vertical member whose primary function is to support vertical loads. 在建筑物和桥梁中最常见的受压构件就是柱，其主要功能就是支承竖向荷载。

In many instances these members are also called upon to resist bending, and in these cases the member is a beam-column. Compression members can also be found in trusses and as components of bracing systems. 在许多情况下，它们也需要抵抗弯曲，在此情况下，将它们称为梁柱。

受压构件也存在于桁架和支撑系统中。

Column Theory （柱理论）Consider the long, slender compression member shown in Fig.1.1a. 考虑如图1.1.a所示的长柱If the axial load P is slowly applied, it will ultimately reach a value large enough to cause the member to become unstable and assume the shape indicated by the dashed line. 如果慢慢增加轴向荷载P，它最终将达到一个足够大的值使该柱变得不稳定(失稳)，如图中虚线所示。

The member is said to have buckled, and the corresponding load is called th e critical buckling load. 这时认为构件已经屈曲，相应的荷载称为临界屈曲荷载。

If the member is more stocky, as the one in Fig.1.1b, a larger load will be required to bring the member to the point of instability. 如果该构件更粗短些，如图1.1b所示，则需要更大的荷载才能使其屈曲。

For extremely stocky members, failure may be by compressive yielding rather than buckling. 对特别粗短的构件，破坏可能是由受压屈服引起而非由屈曲引起。

For these stocky members and for more slender columns before they buckle, the compressive stress P/A is uniform over the cross section at any point along the length. 对这些短柱以及更细长的柱，在其屈曲前，在其长度方向上任意点处横截面上的压应力P/A都是均匀的。

As we shall see, the load at which buckling occurs is a function of slenderness, and for very slender members this load could be quite small. 我们将会看到，屈曲发生时的荷载是长细程度的函数，非常细长的构件的屈曲荷载将会很低。

If the member is so slender (a precise definition of slenderness will be given shortly) that the stress just before buckling is below the proportional limit—that is, the member is still elastic—the critical buckling load is given by 如果构件如此细长（随后将会给出细长程度的精确定义）以致即将屈曲时的应力低于比例极限—即，构件仍是弹性的，临界屈曲荷载如下式给出：22L EIP cr π= (1.1)where E is the modulus of elasticity of the material, I is the moment of inertia of the cross-sectional area with respect to the minor principal axis, and L is the length of the member between points of support. 式中E 为材料弹性模量，I 为关于截面副主轴的惯性矩，L 为支座间的距离。

For Eq1.1 to be valid, the member must be elastic, and its ends must be free to rotate but not translate laterally. This end condition is satisfied by hinges or pins. 要使方程1.1成立，构件必须是弹性的，且其两端必须能自由转动，但不能侧向移动。

This remarkable relationship was first formulated by Swiss mathematician Leonhard Euler and published in 1975. 此著名公式是瑞士数学家欧拉于1975年提出的。