【摘要】 混凝土结构在大荷载作用下出现裂纹,其模态参数呈非线性规律.本文采用分段线性假设进行简化,即认为结构在不同级的荷载下对应有局部的线性特性.对钢筋混凝土T型简支梁在若干不同等级纯力加载并产生相应裂纹的情况下,分别进行试验模态分析,然后用非线性最小二乘拟合的方法,对所得各线性结果进行综合,以推求各种载荷作用(裂纹)下模态参数非线性变化规律.有关研究表明,将这种方法提供的结果用于桥梁承载力的动态法测定是合理可行的.更多还原

【Abstract】 The dynamic parameters of RC structure under different loads and cracks show nonlinear characteristics. This paper assumes that the RC beams have the sectional linear characteristics under different loads and cracks, and treats the sturctures with experimental modal analysis and the identification technique in the frequency and time domain,the results demonstrate that the three lowest resonant frequencies decrease as the loads and the cracks increase. Finaly,the experimental results are synthesized to extrapolate the nonlinear characteristics, the related researches show that the approximate method is feasible for application in the analysis of bridge ultimate load-carrying capacity.更多还原