天津南仓道立交桥主桥斜拉索调索优化方案

Optimization Scheme of Stay Cable Adjustment for Main Bridge of Nancang Avenue Interchange in Tianjin

天津南仓道立交桥主桥为双塔连体四索面预应力混凝土分幅斜拉桥。原设计采取压重方案辅助斜拉索多步一次张拉至设计值。由于压重方案实施困难,该工程采用多步一次张拉法和多步多次张拉法相结合的综合调索技术优化原设计调索方案。采用结构分析软件MIDAS Civil分别模拟优化前后的调索过程,并对该桥的施工阶段、成桥状态进行结构分析。分析结果表明:优化前后边墩支反力、桥塔底部反力变化在5%以内,主梁应力结果基本吻合,成桥恒载索力差在1.58%以内;优化后桥梁各部分受力均满足规范要求。

The main bridge of Nancang Avenue Interchange in Tianjin is a prestressed concrete cable-stayed bridge with conjoined twin pylons,four cable planes and separated decks.In the original design,the stay cables of the bridge would be tensioned to their designed values in one time in multiple steps by the aid of counterweight,however,since it was difficult to realize the counterweight,the original designed cable adjustment scheme was optimized by the comprehensive technique of combining the methods of one-time tensioning in multiple steps and the multiple-time tensioning in multiple steps.The structural analysis software MIDAS Civil was used to respectively simulate the cable adjustment process before and after the scheme was optimized and the structural analysis of the bridge at construction and completion stages was made.The results of the analysis indicated that the variations of reaction force of the side piers and pylon bases before and after the scheme was optimized were all within 5%,the stress of the main girder was basically agreeable,the dead load cable force differences of the completed bridge were within 1.58% and the mechanical behavior of various parts of the bridge after the scheme was optimized could satisfy the requirements in the technical specification.