结合桥梁梁端转角响应的损伤识别研究

Damage detection combined with rotation response of beam end

基于桥梁转角响应易于获取的特点及桥梁影响线的准静态优势,以桥梁实际影响线精准提取前期研究为基础,提出一种结合桥梁梁端转角响应的损伤识别方法。针对梁式桥,结合实际转角影响线构建损伤定位指标,通过定位指标曲线局部峰值确定损伤位置。依此建立包含损伤信息的基函数,对实际转角影响线进行最小二乘拟合识别曲线系数,实现损伤定量。开展车辆过桥数值仿真研究,在20 m长简支梁模型上设置不同损伤工况,模拟二轴车过桥所致转角响应,考虑行车速度、路面平整度和测试噪声等因素影响,以此进行转角影响线的提取及损伤识别。结果表明,同等情况下损伤程度越大,识别结果偏差越小;相较2处损伤,单处损伤的定位更加准确。开展损伤识别模型试验,在5 m长试验梁不同位置处设置2处损伤,进一步进行损伤定位及定量研究。识别试验梁的损伤位置分别为2.09 m和3.05 m,损伤程度分别为0.31和0.47,均与实际值较为接近。上述研究表明:所构建的未损基函数及损伤基函数包含梁结构完整及损伤特征,结合当前状态下梁端转角响应可实现桥梁的损伤识别;损伤识别结果具备较高精度,可为直接利用梁端转角数据进行桥梁的损伤定位定量提供参考。

As rotation response of bridge was easy to obtain and bridge influence line is quasi-static,a damage detection method combining rotation response of bridge beam end was put forward on the basis of previous research on accurate extraction of actual influence line of bridge.For beam bridges,the damage location index was constructed by combining actual rotation influence line,and the damage location was determined by the local peak value of the location index curve.According to this location,the basis function containing damage information was established.The actual rotation influence line was fitted with the least square.The curve coefficient was identified to realize the damage quantitation.Carry out the numerical simulation research of vehicle crossing the bridge,set different damage conditions on the 20 m long simply supported beam model,simulate the rotation response caused by two-axle vehicle crossing the bridge,and consider the influence of driving speed,pavement flatness,test noise and other factors.The rotation influence line was extracted,and the damage was identified.The results show that the larger damage degree under the same conditions,the smaller deviation of detection results.The location of single damage is more accurate than that of two damages.The damage detection model test is carried out and two damages are set at different locations of the 5 m long test beam for further damage location and quantitative research.The damage location of the identified test beam is 2.09 m and 3.05 m respectively.The damage degree is 0.31 and 0.47 respectively,which are close to the actual value.The above research shows the constructed basis function that both the undamaged and the damaged one contain the complete characteristics of beam,and the damage detection of bridge can be realized by combining the rotation response of beam end under the current state.The results of damage detection have high accuracy,which can provide a reference for the quantitative location of bridge damage by directly using the rotation of beam end.