大悬臂预应力盖梁在上部结构换梁施工过程中的受力性能研究

Research on Mechanical Behavior of Large Cantilever Prestressed Bent Cap during Superstructure Girder Replacement Construction

摘要:

大悬臂预应力混凝土盖梁施工中常常采用预应力分批张拉以满足受力需求，若后续桥梁维修更换上部结构，大悬臂预应力盖梁则会面临卸载工况，出现应力过大，甚至混凝土开裂或压溃等不利情况。为研究S20外环泰和路高架在整体换梁施工过程中大悬臂预应力混凝土盖梁的受力性能，建立了施工全过程有限元模型，通过结算结果分析，提出汽车吊联合压重块压重的施工措施，优化全过程施工步骤，解决了盖梁应力超限的问题，保障施工安全，为以后类似工程提供参考。

Abstract:

Large cantilever prestressed concrete bent caps commonly employ staged tensioning of prestressing tendons during construction to meet structural requirements. If bridge superstructure is replaced during subsequent bridge maintenance, large cantilever prestressed bent caps will encounter unloading scenarios, potentially leading to adverse conditions such as concrete cracking or crushing failure. To investigate the mechanical behavior of large cantilever prestressed concrete bent caps during the holistic girder replacement of Shanghai S20 Outer Ring Taihe Road Viaduct, a full-process FE model was established. Analysis of structural calculation results led to the implementation of construction measures utilizing mobile cranes combined with counterweight blocks. This approach optimized construction sequencing, resolved bent cap stress exceedance issues, ensured construction safety, and provided valuable references for similar future projects.