一种基于冲击振动响应分析的桥梁橡胶支座病害诊断方法

提出了一种利用桥梁在冲击荷载作用下动力响应诊断既有桥梁橡胶支座脱空或者受力不均病害的理论方法。以支座刚度的相对下降量为病害指数，计算桥梁冲击响应及其对病害指数的灵敏度，建立灵敏度方程，采用有限元更新技术和优化算法识别支座刚度。一座铁路简支单箱梁桥和一座公路装配式简支箱梁桥的分析结果表明，利用所提病害诊断方法可以准确识别单个或多个支座的刚度变化量，从而判断桥梁支座是否脱空或受力不均。对于铁路简支单箱梁桥，宜将冲击点和响应点布置在扭转振动较大的梁翼缘上；对于公路装配式简支箱梁桥，宜将冲击点和响应点设置在每片主梁的轴线上。

A DIAGNOSIS METHOD FOR BRIDGE RUBBER SUPPORT DISEASE BASED ON IMPACT RESPONSES

A theoretical diagnosis method is proposed for local separation or uneven loading diseases of bridge rubber supports, using the dynamic responses of bridges under impact loads. The support stiffness reduction ratio is defined as a disease index. The impact responses and their sensitivities to the disease indexes are calculated. The sensitivity equation is established and solved, and the support stiffness is identified by the finite element model updating technique and optimization method. A simply-supported railway box-girder bridge and a simply-supported fabricated roadway box-girder bridge are taken as examples. The results show that the stiffness variations of single or multiple supports can be well identified by the proposed disease diagnosis method, and then the supports can be judged whether locally separated or unevenly loaded. For simply-supported railway box-girder bridges, the impact points and response measurement points should be placed on the bridge flanges with larger torsional vibrations, while for simply-supported fabricated roadway box-girder bridges, they should be placed on axis of each girder.