论文总字数：67300字

摘 要

近年来，预应力混凝土连续梁桥由于其跨越能力大、施工方法灵活、适应性强、结构刚度大、抗地震能力强、通车平顺性好以及造型美观等特点，在国内越来越得到广泛的应用。论文设计的是临海公路大桥引桥上部结构设计，大桥位于临海高等级公路如东段新建工程2标段，该桥位于洋口港经济开发区，在K47 738.000段跨越四贯河（规划洋口运河），道路设计中心线与河道边线右偏角约104.1度。四贯河现有河口宽28.7m，水面宽约27.8m。根据省航道调研结论、地方意见和未来港池规划要求，洋口大桥通航标准为60×7m(净宽×净高)，设计最高通航水位为3.04m（1985国家高程基准）。主桥采用50 80 50m连续梁结构，引桥采用25m简支变连续小箱梁结构，总体跨径布置为（3×25） （4×25） （50 80 50） （4×25） （3×25）m，桥梁全长为536.22m。

本设计仅对引桥上部结构进行设计。设计过程如下：

1.确定主梁构造及细部尺寸，本设计采用预制箱形梁，且主梁的高度不变，近墩台处截面通过腹板、底板的加厚以及设置横隔梁等方法使强度得以加强。

2.利用桥梁博士软件分析结构内力，估算纵向预应力筋数量，然后再布置预应力钢束和预应力损失的计算。

3.进行截面强度验算。

关键词：预应力混凝土；先简支后连续梁桥；结构设计；预制安装施工；桥梁博士

Abstract

In recent years, the pre-stressed concrete continuous box Girder Bridge have been more and more widely used internally because of its advantages such as large span capacity, flexible construction methods, adaptability, structural rigidity, anti-seismic capability, traffic convenience and attractive appearance. The graduation project is about the design of superstructure of Linhai bridge, which is located in Rudong country. It’s a new bridge for Linhai highway to across Yangkou River, whose width is about 28.7m. In order to save investment, set the water pier across the river. The main bridge across Yangkou River in a 50 80 50 tapered cantilever construction of pre-stressed concrete continuous box girder, with approach bridge adopted 25m pre-stressed concrete hollow beams, and the overall span arrangement is (4×25) (50 80 50) (4×25).

The procedure of the design is as follows:

1. Chief dimension and constructional details of the main beam are defined, box birder goes as second-degree parabola, for which is generally similar to the change of continuous bridge’s moments of flexion. The section near the pier is strengthened by the provision of thickened webs, bottom slabs and across beam, and the thickness of the web and the bottom slab are changed in linearity.
2. With Doctor Bridge software to analyze internal gross force of the structures, and the internal force composition can be done by the computed results. According to the internal force composited, the evaluated amount of longitudinal tendons can be worked out, and then we can distribute the tendons to the bridge and the loss of pre-stressing is calculated.
3. Check strength of the main cross section.

Key words：Pre-stressed concrete; Simple supported-to-continuous girder bridge; Structure desidgn; Cantilever constructed; Doctor Bridge.

目 录

摘 要 I

Abstract II

绪 论 1

第一章 设计概述........................................................................................................................3

1.1工程概述................................................................................................................................. 3

1.2技术标准 ................................................................................................................................3

1.3设计规范 ................................................................................................................................4

1.4主要材料................................................................................................................................. 4

1.5结构计算相关参数 ................................................................................................................5

第二章 方案选择 ........................................................................................................................5

第三章 桥跨总体布置及结构尺寸拟定 ................................................................................6

3.1桥跨结构图式及尺寸拟定 ................................................................................................6

3.1.1结构图式 ........................................................................................................................6

3.2横向分布计算 .......................................................................................................................10

第四章 荷载内力计算 ...............................................................................................................11

4.1恒载内力计算 .......................................................................................................................11

4.1.1 计算方法 .......................................................................................................................11

4.1.2恒载内力计算结果 .......................................................................................................11

4.2活载内力计算 .......................................................................................................................14

4.2.1活载内力计算结果 .......................................................................................................15

第五章 次内力计算 ...............................................................................................................18

5.1混凝土徐变内力计算 .......................................................................................................18

5.2温度变化内力计算 ...............................................................................................................19

5.3混凝土收缩变形计算 .......................................................................................................21

5.4不均匀沉降内力计算 .......................................................................................................24

5.5温度变化内力计算结果 .......................................................................................................27

第六章 内力组合 .......................................................................................................................31

6.1内力组合结果 .......................................................................................................................31

第七章 预应力钢束设计 .......................................................................................................40

7.1 预应力钢束的布置 ...............................................................................................................40

第八章 施工方法设计 ...............................................................................................................45

8.1引桥施工方法及注意事项 ...............................................................................................45

第九章 截面验算 .......................................................................................................................46

9.1承载能力极限状态计算 .......................................................................................................46

9.2正常使用极限状态计算 .......................................................................................................52

9.2.1抗裂验算 .......................................................................................................................52

第十章 结语 ...............................................................................................................................62

致 谢 .......................................................................................................................................63

参考文献（References） .......................................................................................................64

绪 论

随着我国公路的迅速发展，行车的平稳性和舒适性越来越受到重视。简支梁结构虽然构造简单、受力明确、施工快速，但桥面接缝较多，影响行车，跳车现象也比较严重，不能完全满足公路行车的要求。先简支后连续的桥梁结构可大大减少桥梁接缝，提高行车平稳性和舒适性，且其价格便宜、施工速度快，使用范围也越来越广。根据现场实际情况，本设计中采用4×25m先简支后连续小箱梁结构形式。

毕业设计的目的在于培养毕业生综合能力，灵活运用大学所学的各门基础课和专业课知识，并结合相关设计规范，独立的完成一个专业课题的设计工作。设计过程中提高学生独立的分析问题，解决问题的能力以及实践动手能力，达到具备初步专业工程人员的水平，为将来走向工作岗位打下良好的基础。

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