连续箱梁桥毕业设计

3×20m预应力混凝土连续箱梁分离式立交桥设计

摘要本设计为3×2O米预应力混凝土连续箱梁分离式立交桥。由于设计要求上跨一条二级公路，因此选用互不影响直行交通的分离式立交桥。全桥为双向四车道，分左右两幅桥进行设计，单幅结构横向宽度为12m。全桥采用先简支后连续的方法进行施工。在设计过程中，首先进行尺寸拟定，然后计算荷载横向分配系数，出于安全性和简便性，根据横向分配系数决定出以边梁为例进行内力组合并进行配筋计算,最后进行预应力损失及后期结构截面验算。

关键词分离式立交桥,箱型梁，预应力混凝土，横向分配系数

ABSTRACT

The design for the 3 × 20 meters of prestressed concrete continuous box girder separate overpass. Because a secondary road across the design requirements, so choose independently of each other direct transport of Separated Interchange. Full two-way four-lane bridge, at around two bridge design, single structure transverse width of 12m. Full-bridge using the first method simple and continuous support construction. In the design process, first, the size of the formulation, and then calculate the lateral load distribution coefficient, for security and simplicity, according to the lateral distribution coefficient to determine the side beams and an example of a combination of internal forces Reinforcement, Finally prestressing loss and post-structural cross-sectional checking.

Key Words: Separate overpass, Box girder, Prestressed concrete, Horizontal partition coefficient

目录

绪论 --------------------------------------------------------- 1 1.设计资料 ----------------------------------------------------- 2

1.1 工程概况 ------------------------------------------------ 2

1.2设计标准------------------------------------------------- 3

1.3 设计使用材料及相关参数----------------------------------- 3

1.4 设计使用规范--------------------------------------------- 5

2.桥型方案比选 ------------------------------------------------- 6

2.1预应力混凝土连续箱梁桥----------------------------------- 6

2.2钢筋混凝土箱型拱桥--------------------------------------- 7

2.3预应力混凝土连续刚构桥----------------------------------- 8

2.4比选方案表----------------------------------------------- 9

2.5比选方案分析-------------------------------------------- 10

3.上部结构尺寸拟定--------------------------------------------- 11

3.1尺寸拟定------------------------------------------------ 12

3.2毛截面几何特性------------------------------------------ 15

4.内力组合效应 ------------------------------------------------ 16

4.1 自重作用效应的计算-------------------------------------- 16

4.1.1结构自重作用荷载集度计算--------------------------- 17

4.1.2 内力计算------------------------------------------- 18

4.2 可变作用效应计算---------------------------------------- 22

4.2.1汽车荷载的横向分布系数----------------------------- 22

4.2.2冲击系数------------------------------------------- 28

4.2.3车道折减系数--------------------------------------- 28

4.2.4可变作用效应计算----------------------------------- 28

4.3温差应力的计算------------------------------------------ 33

4.4支座沉降的计算------------------------------------------ 35

4.5内力组合------------------------------------------------ 37

4.5.1按承载能力极限状态设计----------------------------- 37

4.5.2按正常使用极限状态设计----------------------------- 38

4.5.3 计算结果------------------------------------------- 40

5 预应力钢筋的估算与布置--------------------------------------- 42

5.1钢束的估算---------------------------------------------- 42

5.1.1正弯矩配筋估算------------------------------------- 42

5.1.2负弯矩配筋计算------------------------------------- 42

5.2钢束的布置---------------------------------------------- 43

6 预应力损失及有效预应力计算----------------------------------- 47

6.1 预应力钢筋张拉（锚下）控制应力

----------------------- 47

con

6.2 钢束预应力损失------------------------------------------ 47

6.3截面预应力损失合计和有效预应力-------------------------- 53

7.箱梁及截面验算 ---------------------------------------------- 56

7.1基本理论------------------------------------------------ 56

7.2计算公式------------------------------------------------ 56

8 抗裂验算 ---------------------------------------------------- 61

8.1基本理论------------------------------------------------ 61

8.2 正截面抗裂验算------------------------------------------ 62