Papers by Keyword: Rayleigh Damping

Abstract: In the nonlinear time-history analysis for high-rise building, different damping models may lead to results with great difference. Limited by the stable time increment, the stiffness proportional damping is usually neglected in Abaqus/Explicit, and only a simplified mass proportional damping is used, which can be derived from the fundamental frequency and the critical damping factor. In this paper, the influence on the results of this method has been researched by numerical examples, the numerical results also show that the stiffness proportional damping cannot be neglected. Based on these comparisons, a more reasonable damping model is presented for improving the results of high frequencies.

Abstract: Damping ratio is a very important parameter for building structures in the analysis of dynamic response. Story-adding RC structure of light-weight steel is composed by two different material stories. If all the modal damping ratios are defined as the same, as to the dynamic analysis for that structure, the results of analysis will be inappropriate. This paper made some response spectrum analysis on a six-story story-adding RC structure of light-weight steel by finite element analysis software Midas Gen through defining the Rayleigh damping. In the meanwhile, compared the results based on different Rayleigh damping parameters with the results by using the method of strain energy proportional, and got the rule of the definition of Rayleigh damping.

Abstract: The current problems on damping in seismic response analysis of bridges is presented. The Rayleigh damping theory is simply introduced in this paper. Taking the Longtan River Bridge for instance, the finite element model of Longtan River Bridge (left line) is established. Then, the dynamic properties of the bridge is analyzed. Based on this, the Rayleigh damping constants and in an ANSYS dynamic analysis are obtained.

Abstract: Based on the large spring/stiffness method (LSM), this paper develops an improved technique (I-LSM) applicable to structural dynamic analysis with the assumption of Rayleigh damping. To estimate the accuracy of the technique, the dynamic response is analyzed for a 2-DOFs model respectively subjected to uniform/nonuniform seismic excitations. It indicates that the traditional LSM is inapplicable when Rayleigh damping is adopted. And the errors increase monotonously with the aggrandizement of damping. It’s also validated that the I-LSM based on the modification of displacement considering the influences of Rayleigh damping presented in this paper is able to effectively yield results almost identical to those of theoretical methods with errors beneath 4%.

Abstract: To verify the precision and possible applicability of the large mass method (LMM) widely used in multiple-supported structures subjected to non-uniform base excitations, numerical simulations of a two-degrees-of-freedom (2-DOF) finite element model using the Rayleigh damping assumption are performed respectively according to the LMM and the relative motion method (RMM). Through comparisons with the RMM, the error origins 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’s also proved that the improved LMM is able to yield results that are identical to those of the RMM.