基于模态曲率差的钢-混凝土组合梁损伤识别方法研究

Research on Damage Identification Method for Steel-concrete Composite Beams Based on Modal Curvature Difference

在役钢-混凝土组合梁在疲劳荷载和不良环境影响下会发生损伤,造成结构使用性能及承载力下降,需进行必要的健康检测及损伤评估。基于ANSYS有限元模型,对钢-混凝土组合梁栓钉和钢梁损伤前后的模态曲率变化进行分析,并基于模态曲率差进行损伤识别,最后通过模型试验进行验证。结果表明,栓钉损伤后,损伤区域内模态曲率反向斜率消失,损伤区域两端模态曲率差出现极值点,可将模态曲率反向斜率消失的区域和模态曲率差极值点之间的区域判断为栓钉损伤区域。钢梁损伤后,模态曲率和模态曲率差均在损伤位置发生突变,后者变化更明显;模态曲率结果受取值间距和取值路径影响,取值间距取栓钉间距时,按不同路径均可对栓钉和钢梁损伤进行有效识别;模态试验结果可以验证以上方法的可行性,但识别结果受测量误差影响较大。

Under the fatigue loads and adverse environmental effects,the in-service steel-concrete composite beams may experience different forms of damage,resulting in a decrease in structural performance and resistant capacity.Therefore,necessary health detection and damage assessment are needed.The modal curvature changes of steel-concrete composite beam before and after the damage of studs and steel girder were analyzed using ANSYS finite element model.Based on the difference of modal curvature,the studs damage and steel girder damage were identified.Finally,the identification method was verified through model experiments.The results show that,after the stud is damaged,the reverse slope of the modal curvature in the damaged area disappears,meanwhile the value of modal curvature difference at two ends of the damaged area experience extreme points.The area where the reverse slope of the modal curvature disappears and the area between the extreme points of the modal curvature difference can be determined as the damage area of studs.After the steel girder is damaged,both the modal curvature and the modal curvature difference undergo sudden changes at the damage location,with the latter showing more significant changes.The modal curvature is affected by the spacing and path when picking the values.When the spacing between picking points is taken as the spacing between studs,the studs damage and steel girder damage can be effectively identified through different paths.The modal test results can verify the feasibility of the identification method by modal curvature difference,but the identification accuracy is greatly affected by measurement errors.