【摘要】 为检验多点激励分析中广泛应用的大质量法(LMM)的计算精度和适用性,基于瑞利阻尼,以2自由度有限元模型为例,在4组不同的地震动输入下,分别用LMM和相对运动法(RMM)进行了多点激励分析。比较了两种方法的结果,从理论上分析了LMM误差产生的原因,指出了LMM的适用条件,进而提出了改进措施——基于地震动输入阻尼项修正(α项修正)的改进LMM,并验证了该方法的精度和适用性。结果表明:采用瑞利阻尼时,LMM会造成不可忽视的误差,理论上不能用于多点激励分析;瑞利阻尼质量比例系数α是导致误差的主要因素,误差大小与α密切相关;改进的LMM可大幅提高计算精度,与RMM结果高度符合,可以满足工程应用。更多还原

【Abstract】 To verify the practical applicability and accuracy of the large mass method(LMM) widely used in multiple-support seismic excitation analysis of structures,numerical simulations of a two-degrees-of-freedom(2-DOF) finite element model adopting the Rayleigh damping assumption are performed using the LMM and the relative motion method(RMM) respectively under four groups of seismic ground motions.Through comparisons with the RMM,the origin of errors and the applicability of the LMM are discussed.Then the improved LMM is presented herein based on the modification of ground motions considering the influences of Rayleigh damping coefficient α.It indicates that the LMM is not applicable to multi-support excitation analysis in the case of Rayleigh damping,which can cause significant errors.And the errors depend on the damping coefficient α.It is also proved that the improved LMM is able to yield results that are identical to those of the RMM.更多还原