Dynamic test is carried on 12 RC beams,which is subjected to an increasing static load in the middle to introduce cracks.After each loadstep, unloading, and an experimental dynamic monitoring is performed on the beam, then reloading to the next step. Modal analysis is carried out on beams under each loadstep, and beam frequency corresponding to different damage stages are demonstrated.With the mathematical statistics method, mean value and standard deviation of beam frequency reduction rate is given, which confidence intervals are estimated. Furthemore, relationship between beam frequency reduction and load is also found by curve fitting.%设计了12根钢筋混凝土简支梁,进行了逐级加荷一卸荷试验,每次卸荷后,测试梁的动力特性并进行模态分析,得到不同加载条件下梁的自振频率,对频率进行统计分析,得到不同承载状况下RC梁模态频率均值及方差,对频率均值进行了置信区间估计.此外,通过曲线拟合,得到了模态频率的变化量和外荷载之间的关系曲线.
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