基于有限元的在役桥梁综合损伤评测法

A comprehensive evaluation method of damage in in-service girder bridges based on the finite element method

为研究在役桥梁遭受混凝土开裂、钢筋锈蚀、预应力缺损等诸多病害作用下梁体的实际刚度分布状况,根据平截面假定及有限元基本原理,推导梁桥纵向刚度分段求解方程组。借助室外实梁试验,通过施加跨中集中荷载,读取纵梁各代表性分段测点挠度值以修正桥梁纵向刚度。分析结果表明:由于损伤原因及损伤程度各不相同,实际梁体刚度分布随纵向分配区域变化而不同,不能笼统地按照规范选取全梁统一刚度作为桥梁损伤评判标准。建议在役桥梁采用纵向刚度分段计算,以真实、可靠地反映在役桥梁整体损伤状况,锁定损伤范围,估算损伤程度。

In older to study the actual stiffness distribution of beams suffered from all kinds of diseases such as concrete crack,rebar corrosion and prestressed defect,subsection equation of longitudinal stiffness was deduced according to the plane cross-section assumption and the finite element theory.Applying a concentrated load to the mid-span of the beams in-site and obtaining deflection results of the typical sections,longitudinal stiffness of the bridge is corrected and the theory is verified.The analysis results showed that the actual stiffness changed with the areas of different longitudinal distribution and damage.It was improper to take uniform stiffness in the entire beam to evaluate bridge damage approximately.The conclusion suggested that subsection equation of longitudinal stiffness could be used as a reliable tool to identify and estimate damage of in-service bridges.