预应力混凝土连续梁.doc

摘要
此次毕业设计主要是关于小跨度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凭借其结构受力性能好、变形小、伸缩缝少、行车平顺舒适、养护工程量小、抗震能力强等优点而成为最富有竞争力的主要桥型之一。
设计桥梁跨度为40m+40m+40m,,为分离式双幅双向车道。主梁施工采用满堂支架施工。
设计过程如下:
首先,进行桥梁方案比选,通过综合分析,最后确定为梁桥。
第二步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,考虑到抗弯刚度及抗扭刚度的影响,设计采用箱形梁。
其次,计算桥梁的恒载及活载,确定最大弯矩截面,通过计算确定预应力钢筋的面积,定出预应力束的数目,并布置预应力束。
再次,计算预应力损失。
然后,进一步进行截面强度的验算,其中包括承载能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。
然后再进行桥墩与桩基础的设计及计算。
关键字:预应力混凝土连续梁桥,满堂支架施工,截面强度验算
Abstract
Graduation project is mainly on three-span continuous prestressed concrete beam bridge structure design. Continuous prestressed concrete beam bridge, with its structure by the force performance, small deformation, expansion joints, smooth fortable driving and a small amount of maintenance engineering, seismic capability advantages and e the petitive one of the main bridge.
The span of the design bridge is 40m+40m +40 m, broad bridge, divided into four two-way lanes. The main beam construction adopts full framing construction.
Design process as follows :
First, prehensive analysis to elect bridge parison, the final determination is the beam bridge.
Secondly, make sure the main girder structure and the size of the details, It must be consistent with the provisions and construction of the bridge. Taking into account the bending stiffness and the torsional stiffness, the design adopt the box beam.
Thirdly, through the calculation of the bridge dead load and live load, determine the maximum moment section .Determined by calculating the area of prestressed reinforcement, then, set the number of prestressed beam and layout prestressed tendons.
Then, the calculation of loss and the second prestressed forces.
Then, further cross-section strength of checking, including load-bearing capacity limit state and normal use of the extreme limit. In normal use limit state calculation includes sections of the concrete calculation method to stress calculation, prestressed reinforced the tensile