摘 要

Abstract 2

1 绪论 3

1.1预应力混凝土连续梁桥概述 3

1.2设计标准 3

1.3桥址建设条件 4

1.3.1地形地貌 4

1.3.2水文气候 4

1.3.3工程地质条件 4

1.4主要材料 5

1.5规范与技术标准 6

2 桥型方案比选 7

2.1设计要求 7

2.2桥梁纵、横断面设计和平面布置 7

2.3初拟桥型方案 8

2.3.1方案一：预应力混凝土连续梁桥 8

2.2.2方案二：预应力混凝土连续刚构桥 10

2.3.3方案三：预应力混凝土板拉桥 12

2.4方案比选 14

3 桥梁总体布置 16

3.1桥孔布置 16

3.2横截面尺寸拟定 16

3.3桥梁下部构造 18

3.4 主要材料 18

3.4.1混凝土 18

3.4.2普通钢材 19

3.4.3预应力钢束 19

3.4.4预应力锚具 19

3.4.5预应力管道 20

4.1桥梁电算 21

4.2单元划分 21

4.2.1单元划分原则 21

4.2.2具体单元划分 21

接上表 23

接上表 24

4.3 模型截面 24

4.4截面几何特性 25

4.4.1计算方法 25

4.5材料特性 26

5 主梁内力计算 27

5.1施工阶段划分 27

5.2恒荷载内力计算 28

5.2.1计算方法 28

5.2.2控制截面的选定 28

5.2.3恒载内力计算 28

5.3活载计算 31

5.3.1设计车量荷载 32

5.3.2计算方式 32

5.3.3计算结果 33

5.4基础沉降引起的内力计算 34

5.4.1 计算方法 34

5.4.2计算结果 34

5.5温度荷载引起的内力计算 36

5.5.1计算方法 36

5.1.2计算结果 36

5.6内力组合 37

5.6.1内力组合计算要求 38

5.6.2主力组合 38

5.6.3主力 附加组合 40

6 主梁配筋 42

6.1 预应力钢筋数量估算 42

6.1.1估算方法 42

6.1.2 计算公式 42

6.1.3钢束布置估算表 43

6.2预应力束筋的布置 44

6.2.1钢束布置原则 45

7 主梁验算 46

7.1 正截面抗弯验算 46

8.5正常使用极限状态下钢筋验算 53

7.4正截面抗裂验算 54

7.6挠度验算 57

7.6.1预拱度设置 57

7.6.2挠度计算 57

结论 58

参考文献 59

致谢 60

摘要

香都高速六盘水至咸宁段经六盘水市水城县玉舍乡鱼塘村有一溪沟阻隔，计划修建戛拉寨大桥横跨溪沟，本设计为戛拉寨大桥的设计计算，根据桥址情况，拟定出三个比选方案，本设计根据当地的地形地貌，以经济、安全、舒适、美观为原则，最后选取主桥为三跨预应力混凝土连续梁桥的桥型为最终设计方案。主桥全长360米，沿跨中对称布置，主梁采用变截面单箱单室预应力箱梁，能更好的符合桥梁的受力情况，把材料的性能充分发挥，有减轻桥梁自重，减少造价的突出优点。结合桥梁的高度等因素，设计采用平衡悬臂施工法来解决桥高和河深不利于施工的问题。使用平衡悬臂施工法施工时，在桥跨合拢阶段要时刻注意桥梁体系转化时带来的受力变化。

模型设计使用Midas civil软件建立完成，建模后针对不同施工工况分别施加荷载，最后累计到截面上下缘以及挠度。成桥阶段内力计算需要添加静力荷载和移动荷载，静力荷载包括自重以及二期恒载，移动荷载车道荷载（此桥为不设置人行通道故不需考虑人群荷载),计算控制截面影响线，按最不利荷载布置，求出截面最大和最小结构内力。

关键词：预应力混凝土连续梁；单箱单室；变截面箱梁

Abstract

The Liupanshui-Xianning section of the Xiangdu Expressway is blocked by a creek in Yutang Village, Yushe Township, Shuicheng County, Liupanshui City. It is planned to construct the Dalazhai Bridge across the creek. The design is based on the design of the Zalazhai Bridge. According to the situation of the bridge site, Three alternative schemes are proposed. Based on the local topography and landform, the design is based on the principles of economy, safety, comfort and aesthetics. Finally, the main bridge is selected as the bridge design of the three-span prestressed concrete continuous beam bridge as the final design scheme. The main bridge has a total length of 260 meters and is symmetrically arranged along the middle span. The main beam adopts a single-box single chamber prestressed box girder with variable cross-section, which can better meet the force conditions of the bridge, give full play to the performance of the material, and reduce the weight of the bridge. Reduce the outstanding advantages of cost. In combination with the height of the bridge and other factors, the design of a balanced cantilever construction method was adopted to solve the problem that the bridge height and river depth were not conducive to construction. When using the balanced cantilever construction method, attention should be paid to the force changes brought about by the transformation of the bridge system during the bridge span closing phase.

After modeling, the load was applied to different construction conditions and finally accumulated to the upper and lower edges of the section and the deflection. Computation of internal forces during the completion of the bridge requires the addition of static and moving loads. The static load includes its own weight and the second-stage dead load, and the moving load lane load (this bridge is not a pedestrian path so it does not need to consider the crowd load), and calculates the control section influence line. According to the most unfavorable load arrangement, the maximum and minimum structural internal forces of the cross section are obtained.