考虑结构损伤的在役混凝土桥梁有限元模型修正方法

A Method for Updating FE Model of In-service Concrete Bridge Considering Structural Damage

混凝土桥梁结构及材料参数在服役期间处于动态变化过程(如材料劣化),在桥梁完工投入运营之后再测定桥梁的材料或者结构参数较为困难,且采用基于桥梁初始设计参数建立的有限元模型来对其进行模拟的精度有限。为建立考虑结构损伤的在役混凝土斜拉桥的高精度有限元模型,提出了一种基于桥梁荷载试验的混凝土斜拉桥有限元模型修正方法。首先以一座混凝土斜拉桥为依托工程,建立了桥梁初始Midas有限元模型。在考虑混凝土斜拉桥结构特点、施工误差以及可能出现的结构损伤部位的基础上,选取4个结构参数及1个试验参数作为待修正参数。根据依托工程桥梁荷载试验特点及常规试验内容,选择了4个覆盖了结构静、动力特性的指标作为目标函数,根据有限元计算结果建立了待修正参数与目标函数之间的响应面方程。最后根据依托工程荷载试验的结果,结合响应面方程对初始有限元模型进行了修正。结果表明:采用修正后参数的计算结果与实际桥梁施工情况相符,修正后的桥梁有限元模型具有较高精度,可较好地反映出实际桥梁工程在弹性阶段的静、动力力学状态;所提出方法可通过桥梁荷载试验来反推桥梁当前状况下的参数状态,实现对桥梁结构的精确模拟,该方法不仅适用于新建桥梁也可对长期运营的桥梁的结构状态进行反推和模拟。

Concrete bridge structure and its material parameters are in a dynamic change process(such as material deterioration)during service,it is difficult to determine the material or structural parameters of bridge after the bridge is completed and put into operation,and the accuracy of simulating it with the FE model based on the initial design parameters of the bridge is limited.In order to establish a high-precision FE model of in-service concrete cable-stayed bridge considering structural damage,a method for modifying the FE model of concrete cable-stayed bridge based on the bridge load test is proposed.First,taking a concrete cable-stayed bridge as the supporting project,the initial FE model of Midas is established.Then,considering the structural characteristics,construction errors and possible structural damage positions of the concrete cable-stayed bridge,4 structural parameters and 1 test parameter are selected as the parameters to be corrected.According to the characteristics of the bridge load test of the supporting project and the conventional test content,4 indicators covering the static and dynamic characteristics of the structure are selected as the objective function,and the response surface equation between the parameters to be corrected and the objective function is established based on the FE calculation result.Finally,the initial FE model is revised based on the result of the engineering load test and the response surface equation.The result shows that(1)The calculated result based on the revised parameters is consistent with the actual bridge construction condition,and the revised bridge FE model has high accuracy and can better reflect the static and dynamic mechanical behaviors of the actual bridge project in the elastic phase.(2)The proposed method can reverse the parameter state of the bridge under current condition through the bridge load test to realize the accurate simulation of the bridge structure.The method is not only suitable for newly built bridges,but also can reverse and simulate the structural state of long-term operating bridges.