Research On Seismic Performance Of Masonry Structures In Villages And Towns Considering Randomness Of Materials

There is no strict seismic design for masonry structures of villages and towns in China,and the process from block forming and mortar making to overall construction is relatively rough.In addition,the economic and technical conditions of villages and towns are relatively underdeveloped,which produce the variety of material randomness easily,thus affecting the seismic performance of the structures,and even further affecting the effective evaluation of the performance of the masonry structures.In this paper,based on numerical simulation,the three kinds randomness of masonry materials were considered from elastic modulus E,tensile strength f_t,and compressive strength f_m,and the effects of the seismic performance of the masonry structures in villages and towns were investigated.The main research contents and achievements of this paper are as follows:（1）The masonry modeling method based on the MARC software platform was established.Specifically,an integral modeling method was adopted to model for masonry walls,structural columns,and ring beams in blocks.Then according to the modeling way,reversed low cyclic loading tests of four types of walls,including with/without constraints and with/without openings,were simulated respectively.And the accuracy of the modeling method was verified by checking with the experimental results.（2）The effects of material randomness on the seismic performance of masonry walls were studied.Monte-Carlo method was adopted in combination with MATLAB and Python to carry out random analysis of the masonry walls with/without constraints,and the mean value and coefficient of variation of seismic performance indexes were analyzed.The results show that:（1）considering the randomness E,f_t and f_mseparately,that of f_m is relatively the largest;（2）compared to separate analyses,comprehensive consideration has a greater impact on the seismic performance of masonry walls.（3）The deformation capacity of masonry walls is more affected by the randomness of materials than that of bearing capacity.（4）The seismic performance of the unconstrained wall is more affected by randomness than that of restrained walls.（3）The probability model of the Trifold skeleton of with/without constraints walls was proposed respectively.Considering the randomness of E,f_t and f_m comprehensively,random analysis was carried out on with/without constraint masonry walls with the four-aspect ratio of0.5,0.68,0.8 and 0.1 individually,The normalized skeleton model indexes,Δ_c/Δ_u,P_c/P_u,Δ_f/Δ_u,were obtained,and the ORIGIN was used to fit them to determine the mean value and coefficient of variation of their distribution.（4）The effects of material randomness on seismic performance of masonry structure was studied.By using the Monte Carlo method and Pushover method,the random analysis of masonry structure with/without constraints was carried out,and the average value and coefficient of variation of its seismic performance index were analyzed.The results show that:（1）Among the influences on the aseismic performance of masonry structure,the effect of considering the randomness of E,f_t,and f_m comprehensively is the largest,followed by f_m,f_t,and E separately.（2）Unconstrained masonry structure is more affected by material randomness.（3）The deformation capacity is more affected by the randomness of the material than the bearing capacity.（4）The interlayer ultimate deformation capacity affected by the randomness of each material is the same basically.Finally,by comparing the maximum inter-story displacement angle,the collapse possibility of masonry structures in villages and towns affected by the randomness of materials was evaluated.