论文总字数：71011字

摘 要

预应力混凝土连续梁桥是工程上广泛使用的一种桥型,它不但强度高、抗震能力强、刚度好及抗裂性强,而且具有行车平稳、养护工作量小、伸缩缝少、造型简洁美观、设计及施工经验成熟等特点。

该设计针对桥址处地形地质条件，从桥跨布设及施工方法等多方面进行综合比较，同时充分考虑设计参数和环境影响，选择了172m三跨变截面预应力混凝土箱形连续梁桥。采用双向6车道，桥宽为36m，由两个单箱双室截面组成；梁高采用变高度梁， 按二次抛物线变化，边跨支点处梁高2m、跨中处梁高2m、中跨支点处梁高4.4m，采用满堂支架施工。

设计计算时，首先进行恒载内力计算、利用《公路钢筋混凝土及预应力混凝土桥涵设计规范》和Midas Civil l进行活载内力计算、次内力的计算，在此基础上按承载能力极限状态和正常使用极限状态进行荷载效应组合，并绘制弯矩和剪力包络图；其次，该设计按照全预应力构件设计，根据正截面抗裂要求，确定预应力钢筋的数量，按照钢筋束布置构造要求和布置原则进行钢筋束的配置，并依据后张法进行预应力损失和有效预应力的计算；再者，对上部结构进行正截面抗弯承载力、斜截面抗剪承载力、正截面抗裂、混凝土法向应力验算，最后根据《公路桥涵地基与基础设计规范》（JTJ 024—85）进行桥墩设计和竖向承载力、水平承载力验算和桩基础设计。该设计完成了桥梁上部结构、下部结构的设计和验算，并编制了计算书和相关图纸。

计算结果表明该桥在正常使用极限状态及承载能力极限状态下，桥梁结构各主要受力构件强度、刚度及变形均满足规范要求。

关键词：预应力混凝土 连续梁桥 箱梁 满堂支架施工

Jiang Su Xi Cheng Bridge Right Frame Scheme C

Abstract

Prestressed concrete continuous beam bridge is widely used in a bridge type, it is not only high strength, strong seismic capacity, good rigidity and crack resistance, and has a smooth traffic, conservation of small workload, less expansion joints, simple modeling Beautiful, design and construction experience mature and so on.

   The design is based on the terrain and geologic conditions of the bridge site, and the comprehensive comparison is made from the bridge and bridge construction method and the construction method. At the same time, considering the design parameters and environmental impact, the 172m three variable cross section prestressed concrete box continuous beam bridge is selected. Using two-way 6-lane, the bridge width of 36m, composed of two single-box double-room section; beam height using variable height beam, according to the second parabola changes, the edge of the fulcrum at the beam height of 2m, Fulcrum at the height of 4.4m, full of stent construction.

   In the design calculation, the calculation of the internal force of the dead load is carried out, and the calculation of the internal force and the calculation of the internal force is carried out by using the "Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts" and Midas Civil l, and on the basis of the bearing capacity limit state and normal Secondly, the design is based on the design of the whole prestressing member. According to the requirement of the cross section crack, the number of prestressed steel bars is determined, and the structural requirements of the tendon are arranged according to the requirements of the reinforced beam structure. And the layout principle of the reinforcement of the beam structure, and according to the post-tension method for prestress loss and effective prestress calculation; Moreover, the upper structure of the normal section of the bending capacity of bending, oblique cross-section shear capacity, (JTJ 024-85), the bridge pier design and vertical bearing capacity, the horizontal bearing capacity checking and the pile foundation design are carried out according to the "Highway Bridge and Culvert Foundation and Foundation Design Code" (JTJ 024-85). The design of the bridge to complete the structure, the lower structure of the design and verification, and the preparation of the calculation of books and related drawings.

   The results show that the strength, stiffness and deformation of the main components of the bridge are in accordance with the normative requirements under the normal limit condition and bearing capacity limit.

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Keywords: prestressed concrete ，box girder ，continuous beam bridge， construction Full Support.

第一章 方案设计

1.1跨径布置

1.1.1标准跨径

江苏锡澄大桥实际桥长172m。按照设计任务书中的要求，本联设计采用变截面连续箱梁结构形式。为了在整体上保证桥的整体协调及美观性，跨径布置时，要和前后联协调好，通过计算调整，最终确定本联的跨径布置如下：

48m 76m 48m= 172m

标准跨径(相邻墩身轴线距离)布置图示如图 1-1。

48m 76m 48m

1 2 2 3 4

图1.1 .标准跨境（相邻墩身轴线距离）布置图

本联为三跨连续梁桥，三跨连续梁合理布置。由参考文献[1]第二章第一节(P69)可知，三跨连续梁合理的跨径布置为边跨与中跨之比为0.6:1到0.7:1之间，且对称布置，该桥选择的边跨与中跨比为0.632:1,并对称布置。

1.1.2 计算跨径

上面的跨径布置为标准跨径，计算跨径还要考虑到两边跨伸缩缝及支座尺寸的的折减。为了减小伸缩缝的宽度，把固定支座放在2#墩上，让梁体向两边伸缩。由设计任务书可知 本桥的设计年平均温差为±20℃，混凝土材料的温度膨胀系数为 1.0×10-5/℃，则可计算得左右两边的伸缩缝宽度至少分别为：3cm，4cm；再考虑到支座尺寸的影响，计算跨径布置如下图 1-2：

0.56m 48m 76m 48m 0.56m=173.12m

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