【摘要】 用高斯白噪声模拟结构的脉动激励,获取其有限测点上有限时长的加速度反应并加入测量噪声;用改进NExT-ERA法识别含误差的不完备模态;用稳定图法和奇值法选择高精度的模态;进而比较由高精度模态建立的基于模态柔度、模态应变能、小波组分能量的损伤指标识别悬索桥损伤的能力和抗噪性,以及有限传感器的不同布置方案对损伤识别能力的影响。西堠门悬索桥的数值计算结果表明:该模态识别和选择的方法是有效的;基于模态应变能和模态柔度的指标对加劲梁损伤有一定灵敏度和抗噪性;能识别的损伤程度取决于模态误差和信噪比的大小;传感器优化布点可提高损伤指标的灵敏度。更多还原

【Abstract】 Using Gaussian white noises to obtain acceleration responses with limited recording lengths at finite degrees-of-freedom(DOF),authors analytically simulated structural ambient excitations.The measurement noises were added in.Then,incomplete modal parameters containing errors were identified by using an improved NExT-ERA method;high precision modes were selected based on singular values method and stabilization diagram method.Damage capacity and noise immunity of suspension bridge detected by modal flexibility,modal strain energy and wavelet packet component energy which was established under high precision modal state were contrasted.Influences of different sensor localization schemes at finite DOF on damage detection capacities were discussed.Numerical example results of Xihoumen Suspension Bridge show that methods of modal identification and mode selection in this paper are effective;damage indexes of incomplete modal flexibility and modal strain energy are relatively sensitive and robust to damage of girders;identified damage extents lie on the extents of modal errors and signal-noise ratio;sensitivity of damage indexes can be improved by optimum sensor localization.更多还原