支承门式墩施工支架的既有线桥梁可靠性分析

Reliability analysis of existing linebridges with supporting portal pier construction supports

针对支承门式墩施工支架的既有线桥梁可靠性分析研究相对不足的问题,研究结合实际工程实例,建立了一种针对门式墩施工对上跨既有线桥梁进行可靠性分析的计算方法。该方法首先计算初步设计的施工支架对既有桥梁的作用力;然后对既有桥梁进行实体建模分析,主梁采用八节点六面体线性减缩积分单元(C3D8R),预应力筋采用两节点线性三维桁架单元(T3D2),并将预应力钢筋以嵌入(Embed)方式置于混凝土模型内部,网格尺寸设定为1 cm,严格依照图纸进行精细装配;此外,通过模拟降温过程以施加预应力筋的预应力;然后对混凝土的强度、变形以及开裂情况进行可靠性分析。基于分析结果对初步设计的支架结构提供了针对性的改进建议。实际工程应用显示:采用这种方法进行计算,能够切实保证门式墩施工过程的安全性,同时确保既有桥梁在施工阶段的可靠性。

In response to the relatively insufficient research on the reliability analysis of existing line bridges supported by portal pier construction brackets,this study combines practical engineering examples to establish a calculation method for the reliability analysis of existing line bridges over portal pier construction.This method first calculates the force exerted by the preliminary designed construction support on the existing bridge;Then,a solid modeling analysis was conducted on the existing bridge.The main beam used an eight node hexahedral linear reduced integral element(C3D8R),and the prestressed steel bars used a two node linear three-dimensional truss element(T3D2).The prestressed steel bars were embedded inside the concrete model with a grid size of 1 cm,and fine assembly was strictly carried out according to the drawings;In addition,by simulating the cooling process to apply prestress to the prestressing tendons;Then,a reliability analysis is conducted on the strength,deformation,and cracking of the concrete.Based on the analysis results,targeted improvement suggestions were provided for the preliminary design of the support structure.Practical engineering applications have shown that using this method for calculation can effectively ensure the safety of the construction process of portal piers,while also ensuring the reliability of existing bridges during the construction phase.