Comparison of the calculation results of structures for specified accelerograms by nonlinear static and nonlinear dynamic methods

Abstract

Relevance. Modern national standards for the design of buildings and structures for seismic impacts suggest the calculation of structures in a nonlinear setting. Only linear-spectral method, which has been used and is still used, is not enough for calculation. This is due to the fact that it does not allow directly taking into account the nonlinear work of the structures. To solve the problem, nonlinear dynamic methods of calculation in the time domain can be used. At the moment, such methods are implemented only in specialized software complexes, and in most cases cannot be used by ordinary designers. Thus, it became necessary to apply simpler nonlinear calculation methods. In foreign standards for calculation of seismic resistance of buildings and structures, nonlinear static methods, or pushover analysis, have long been used. But in the national design practice until recently, these methods have not received due attention. Thus, the relevance of the study of the possibility of using these methods in engineering practice is beyond doubt. The aim of work. The purpose of this article is to estimate the accuracy of a nonlinear static method in comparison with a nonlinear dynamic method when calculating structures for given accelerograms. Solution technique. In the article three steel frames are considered: one-, threeand seven-story. The selection of sections was made in accordance with the requirements of the national standards on earthquake-resistant construction for seismic loads of the basic safety earthquake (BSE) level. Next, frames are designed for the seismic loads of the maximum considered earthquake (MCE) level on a set of accelerograms of different frequency composition. The calculation was performed by a nonlinear dynamic method in the LS-DYNA software package and a nonlinear static method in the LIRA 10.6 and MATLAB software complexes. Results. Calculations showed that in all the cases considered, except for one, a nonlinear static method showed a conservative estimate of the response of the system, in comparison with the nonlinear dynamic method. But in some cases the reaction was greatly overestimated.