带裂缝钢筋混凝土梁损伤诊断的振动方法

建立了健康的和带有理想裂缝的钢筋混凝土梁的分离式有限元模型,推导了其中四节点矩形粘结单元的刚度矩阵。利用该模型可以计算它们的振动特性参数,研究其局部损伤与振动特性参数的关系。有限元模型数值仿真计算结果与实际测试结果相吻合。数值仿真计算及实际测试结果均表明:固有频率是进行钢筋混凝土梁裂缝类损伤定性辨识的重要指标;曲率模态振型和应变模态振型是钢筋混凝土梁裂缝类局部损伤的敏感参数,利用它们的模态绝对残差向量可以实现实梁裂缝类损伤的准确定位识别;曲率模态振型和应变模态振型的绝对残差向量范数,与裂缝类损伤的严重程度具有单调性关系,可以基于其进行裂缝类损伤的定量辨识。

Damage Diagnosis Based on Vibration Method For Reinforced Concrete Beam with Crack

The separate finite element model is established for the healthy reinforced concrete beam(RCB) and the RCB with perfect crack in this paper,and stiffness matrix for sticking unit in the model with 4 nodes is deduced.The parameters of vibration characteristic are able to be calculated for the healthy and damage RCB with the model.The relationship between the damage and the parameters is able to be studied by using this model.The numerical result tallies with the outcome from testing.After the numerical calculation and testing,three conclusions can be drawn.Firstly,the nature frequency is important guideline to determine the nature of the damage,such as the cracks,in the RCB.Secondly,the curvature mode shape and the strain mode shape are the sensitive parameters of the local damage in the RCB and the location of crack can be distinguished exactly by using the mode absolute residual vector in testing. Thirdly,the relationship is monotone between the norm of absolute residual vector of curvature mode shape and strain mode shape and the damage severity,and the damage severity can be evaluated based on the norm.