预应力混凝土连续梁桥上部结构的设计论文道桥

摘要

本设计主要是关于预应力混凝土连续梁桥上部结构的设计。预应力混凝土连续梁桥以结构受力性好、变形小、伸缩缝少、行车平顺舒适、养护工程量小、抗震能力强等而成为最富有竞争力的主要桥型之一。

设计桥梁跨度为30m+30m+30m+30m+30m，分为两幅设计，单幅为单箱单室，桥面总宽26m,双向4车道。主要采用现浇混凝土施工，按桥梁纵坡由低到高进行浇筑，一旦浇筑必须按每联连续浇筑，不得停歇。本桥设计分为双幅14联，按联施工。

设计过程如下：

首先，确定主梁主要构造及细部尺寸，它必须与桥梁的规定和施工保持一致，考虑到抗弯刚度和抗扭刚度影响，设计采用箱型粱。主梁的高度呈成二次抛物线变化，因为二次抛物线近似于连续梁桥弯矩变化的曲线。

其次，利用桥梁博士电子软件分析结构的总内力（包括恒载和活载的内力计算），用于计算内力组合结果也由桥梁博士电子软件计算而得，从而估算出纵向预应力筋的数目，然后再布置预应力钢丝束。

再次，计算预应力损失及次内力，次内力包括先期恒载徐变次内力、先期预应力徐变次内力、后期合拢预应力索产生的弹性次内力、局部温度变化次内力。

然后进一步进行截面强度验算，其中包括承载力极限状态和正常使用极限状态。在正常使用极限状态验算中包括计算截面的混凝土法向应力验算、预应力钢筋中的拉应力验算、截面的主应力计算。

最后，通过手算计算出桥面板及桥墩的形式及受力情况，最终整理成本桥设计的总体信息。

关键词：预应力混凝土连续梁；后张法；现浇砼施工

Abstract

The graduate design is mainly about the design of superstructure of long-span pre-stressed concrete continuous box Girder Bridge .Pre-stressed concrete continuous Girder Birdge become one of main bridge types of the most full of completion ability because of subjecting to the dint function with the structure good,having the small defomation,few of control joint,going smoothly comfort,protected the amout of engineering small and having the powerfully ability of carthquake proof and so on.For time and ability limited,the design of the substructure,transverse pre-stressing and vertical pre-stressing is not considered.

The spans of the bridge are 30m+30m+30m+30m+30m m,main beam is respective designed,each suit has one box one room and four traffic ways of all,the width of the bridge surface is 26m.The major girder applies cantilever hung-basket bearing,symmetric equilibrium construction. The bridge design is divided into 126 units and 48 construction section

The design process is as follows:First, make sure the main girder structure of details and size, it must be with the rules and regulations of the bridge construction keeps consistent, considering the bending stiffness and wrest resistant effect stiffness, design USES a box beams. The height of the main girder is into two parabolic change, because two parabolic approximate continuous girder bridge bending moment the curve of the change.

Secondly, the use of bridge structure analysis of electronic software dr total internal force (including the dead load and live load of internal force calculation), used to calculate the combination of internal force of the bridge by dr software and electronic calculation, and estimate the number of longitudinal prestressed reinforcement, and then arrangement of prestressed steel wire.

Again, the loss of prestress and internal force calculation time, time constant load first internal force including creep time internal force, first prestressed creep time internal force, closed late prestressed cable effects of elastic time internal force, local temperature changes of internal force of The Times