天津南疆港预应力连续梁桥悬臂施工监控

Research on the Construction Control of Cantilever of Prestressed Continuous Bridge in Tianjin Nanjiang Haven

研究目的:天津南疆港复线公路桥是大型车辆进出南疆港的重要交通通道。设计中考虑一个车道承受特殊荷载,车辆为750 kN三轴车,车距为10 m,该桥的设计荷载远大于公路-Ⅰ级荷载,有必要解决梁部悬臂在施工中的挠度控制和应力控制问题,以保证桥梁顺利合龙并达到理想的线形及施工过程中的安全。研究结论:只有合理控制桥梁各阶段挠度、应力,合理确定立模高程,才能保证桥梁线形和应力分布达到设计要求;挠度的测量应安排在日出之前进行,以消除日照温差的影响;计算中混凝土弹性模量应取用现场实测值;本桥施工监控中,使用参数识别法对施工中产生的误差进行调整,效果良好,行之有效;应力测试中收缩、徐变的影响较大,分阶段计算它的影响,概念清楚、使用方便。

Research purposes： The double -lane highway bridge in Tianjin Nanjiang Haven is an important traffic passageway for large - sized vehicles going to and coming from Tianjin Nanjiang Haven. One lane is designed for the vehicle with three axis, vehicle weight of 750 kN and vehicle distance of 10 m. The design load of the bridge is great than Ⅰ grade highway. So it is necessary to control distortion and stress in cantilever cast for the purposes of ensuring the bridge closure and construction safety, and obtaining a perfect bridge type of line. Research conclusions： Only distortion and stress of bridge is controlled in construction and the moulding board elevation is ensured, the bridge type of line and stress distribution can satisfy the design requirement. The distortion measurement should be conducted before sunrise to eliminate effect of temperature difference. The real field measured values of the concrete elastic modulus must be adopted in computation. In construction control of this bridge, the errors happened in construction is modified by adopting parameter identification method, obtaining a good result. As the effects of shrinkage and creepage are evident in stress testing, the effect should be calculated to each construction phase for the clear and easy usage.