论文总字数：56810字

摘 要

本毕业设计的题目是3×20m预应力混凝土等截面连续箱梁桥的上部结构设计。随着材料和施工技术的飞速发展，以及预应力混凝土连续梁桥的优良的力学特性，该桥型成为了现代桥梁结构的主力军，占据了极大的比例。在公路和市政道路行车要求不断提升的大背景下，在中小跨径桥梁中，连续梁桥具有良好的受力性能、协调变形较小、伸缩缝少、行车平顺舒服、造型简洁大方、养护工程量少和较好的抗震性能使得该桥型的应用十分广泛，成为广大地区建设桥梁的主要结构类型。本设计是昆山中环高架互通D匝道第二联。主桥为预应力混凝土等截面连续箱梁，跨径组合为（3x20）m，桥梁宽度为12.3m，采用满堂支架现浇施工方法。下部结构采用实体墩，钻孔摩擦桩基础。

桥梁设计荷载为公路－I级，结构设计安全等级为一级。

设计过程简述如下：

(1)确定主梁构造与拟定截面具体尺寸；本次设计方案采用等截面连续箱型梁，主梁的截面下边缘在4号墩附近线性变化，其余部分采用等高箱梁，在近墩台应力集中处加厚腹板和底板进行加强。

(2)运用AutoCAD、Midas civil电算软件运算上部结构内里，估算预应力钢筋用量，布置、调整预应力钢束。

(3)运用AutoCAD、Midas civil等软件进行截面强度验算；验算桥梁上部结构在持久状况、短暂状况下的内力、应力和裂缝宽度。

(4)输出电算软件数据，手算验证个别截面，整理输出验算结果形成报告。

关键词：满堂支架现浇施工；AutoCAD；Midas civil；预应力混凝土等截面连续箱梁

(3 *20) m prestressed concrete continuous box girder bridge design

Abstract

The topic of this graduation project is the superstructure design of 3 * 20m prestressed concrete continuous box girder bridge with constant cross-section. With the rapid development of materials and construction technology, as well as the excellent mechanical properties of prestressed concrete continuous girder bridge, the bridge has become the main force of the modern bridge structure, which occupies a large proportion. In the background of highway and municipal road traffic demand rising, the small and medium span bridge, continuous girder bridge has good mechanical properties, deformation is smaller, less expansion joints, driving smooth and comfortable, concise and generous, less maintenance and good seismic performance of application of the bridge is very extensive, mainly the construction of the bridge structure has become a wide area of type. This design is Kunshan central elevated interchange D ramp second. The main bridge is a prestressed concrete continuous box girder with constant cross section (3x20) m, and the width of the bridge is 12.3m. The substructure adopts the solid pier, the bored pile foundation.

The bridge design load for highway grade I, grade level security structure design.

The design process is as follows:

(1) to determine the main structure and develop specific section size; the design scheme with constant cross section continuous box girder, girder section under the edge in the vicinity of a linear change of pier No. 4, and the remaining part of high box girder, the stress concentration at the pier near the thickened web and bottom strengthening.

(2) use AutoCAD, Midas civil software to calculate the upper structure inside, estimate the amount of prestressed steel, layout, adjust the prestressed steel beam.

(3) use AutoCAD, Midas civil and other software to check the strength of section, check the internal force, stress and crack width of the superstructure of the bridge under the condition of lasting and transient.

(4) the output of the computer software data, hand calculation verification of individual sections, finishing the results of the calculation of the output report.

Key words: full support cast-in-place construction; AutoCAD; Midas civil; prestressed concrete continuous box girder with constant cross-section

目 录

摘要 I

Abstract II

绪论 1

第一章 设计信息概述 2

1.1 设计桥梁形式 2

1.2技术标准及设计参数 2

第二章 设计要点 4

2.1 桥型布置与尺寸拟定 4

2.2 结构有限元建模 5

2.3桥梁 7

第三章 施工方案设计 11

3.1 预应力混凝土箱体施工方案 11

3.2 预应力施工 11

第四章 预应力钢束 13

4.1预应力钢束估算 13

4.2预应力钢束布置 15

第五章 桥梁施工阶段数据信息 18

第六章 持久状况下承载能力极限状态验算 30

第七章 持久状况下正常使用极状态验算 37

7.1 抗裂验算 37

7.2应力验算 49

7.3受拉区钢筋拉应力验算 53

7.4挠度验算 58

第八章 持久状况下截面验算图示 60

第九章 结束语 63

致谢 64

参考文献（References） 65

附录 66

绪论

随着城市经济的发展，人口数量的不断增加，导致城市用地紧张，加之交通量的剧增和城市快速化进程的推进，城市快速不断发展。在快速路的设计中，跨线桥的应用不可避免，又因连续梁桥的舒适性较好，在城市道路中应用较为广泛。悬臂梁桥在大跨径桥梁中应用较多，加之施工工艺较为复杂，需要大型的桥梁预制场，不适合城市桥梁的应用。小箱梁桥仍需要较大的预制场，而且小箱梁的视觉不如整体箱梁桥，综合跨径、施工、维护、造价、行车舒适性等因素，在已有的桥跨布置情况下，我们选择后张法预应力混凝土等截面连续箱梁桥。该桥梁结构通过预先张拉高强钢筋是混凝土受压，充分利用混凝土和预应力钢筋两种材料的优点，提高了混凝土的抗裂性能，也大大减少了混凝土的用量，减少了自重，提高了经济效益。

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