Numerical Analysis On Seismic Collapse Resistance Performance Of Masonry Structures In Villages And Towns

With the improvement of China’s economic,there is an urgent need to improve the seismic safety of buildings in the vast villages and towns.Most of the masonry buildings have not been strictly designed and constructed,and the ability to resist earthquake collapse is relatively poor,so there are severe earthquake disaster threats in villages and towns.In this paper,the seismic collapse resistance and collapse vulnerability analysis of typical masonry structures in villages and towns are carried out by numerical simulation method.The collapse mechanism and collapse mode of the structure under large deformation are revealed,and the collapse vulnerability curve of the structure is obtained.The main research work and conclusions are as follows:（1）Based on the general finite element software MSC.Marc,considering the analysis accuracy and calculation efficiency,a refined finite element numerical analysis model that can be used to simulate the whole collapse process of typical masonry structures in villages and towns under strong earthquakes is developed.The numerical simulation of elasto-plastic timehistory analysis was carried out on the shaking table test of a two-story masonry structure.The numerical simulation and test results show that the damage of the first floor of the structure is more serious,and the damage is mainly concentrated in the corner of the door and window,which verifies the reliability of the refined finite element numerical analysis model.（2）According to the actual situation of the vast rural areas,a refined finite element model of the typical masonry structure of the villages and towns with different seismic structural measures was established,and the elasto-plastic time-history analysis was carried out by using the finite element contact algorithm and the life-death element control technology,so that the whole process of the collapse of the structure is simulated.By examining the failure state,displacement response,collapse process and collapse mode of each model,the influence of constructional column,precast slab and slab support lengths,completely non-seismic structural measures and ground motion forms on the collapse resistance performance of the structure are analyzed.（3）Based on the empirical equation of the I-K model parameters of the unconstrained masonry wall and the constrained masonry wall,through the USPRNG subroutine interface of MSC.Marc software,the displacement-force hysteresis relationship code of the interlayer spring is written,and the simplified shear layer model of single masonry structure is established.Pushover analysis based on multi-point displacement control is carried out on the refined model and simplified model of masonry structure in this paper.By comparing the capacity curve results of the two models,it is found that the parameters of each feature point calculated by the simplified model agree well with the refined model,which verifies the reliability of the simplified shear layer model.（4）A simplified shear layer model of rural masonry structure with different seismic structural measures is established.IDA analysis of 23 ground motions is carried out on each model,and the lognormal distribution function fitting is carried out on the analysis data,and the collapse vulnerability curves of different models are obtained.According to the average collapse capacity index,the collapse resistance of different structures is quantitatively evaluated,and the influence of structural columns,precast slab and completely non-seismic structural measures on the collapse vulnerability of structures is analyzed.