Experimental Study On Seismic Behavior Of Reinforced Masonry Structure Based On Spandrel Failure Mode

Masonry structure plays the role of mainstream building structure form in less developed cities and medium-sized towns.The masonry structure built in the middle and later period of last century still has a large amount of possession and utilization rate at present.At the same time,some masonry structures with special characteristics exist as unique cultural symbols,which are symbolic building to witness the glorious history of China.In recent years,frequent earthquakes have caused varying degrees of damage to masonry structure with low seismic fortification capacity.Meanwhile,the unique cultural characteristics and application situation have made it difficult to reconstruct masonry structure in large areas.Consequently,it is significant to realize the overall seismic performance of existing masonry structure by means of reasonable and effective reinforcement measures.In order to cope with the deficiencies in the design code of masonry structure and the lack of effective and universal reinforcement design theory in the process of reinforcement and transformation,this paper aims to remedy the deficiencies in the analysis and control of failure mode of masonry structure at home and abroad,and puts forward the basic ways and methods to realize the spandrel failure mode of existing masonry structure by means of comparison and analysis of test results.It is expected to improve the overall seismic performance of existing masonry structure.The main contents of this paper are as follows:(1)The main influencing factors of different failure mode of masonry structure were analyzed,and some influencingfactors were selected to establish finite element model and analyze simulation results.(2)Based on the finite element model,the overall structure opening specimen and the spandrel sub-structure specimens were designed and manufactured to carry out quasistatic tests;The feasibility of the finite element simulation method and correctness of the simulation results were verified by the test results.(3)The steel reinforced grout(SRG)reinforcement method was selected to reinforce the each damaged specimen purposefully and quantitatively,and the quasi-static tests were repeated.(4)The transfer of failure mode before and after reinforcement was compared;The bearing capacity,deformation performance and energy dissipation capacity were analyzed.The conclusions of this paper are as follows:(1)It was clear that the stiffness ratio and vertical load of the piers and spandrels were the main factors affecting the different failure mode of masonry structure.(2)As far as the failure mode was concerned,the failure mode of the reinforced specimens was transfered from "piers failure mode" to "spandrels failure mode",which was more reasonable.(3)In terms of the seismic performance,the restoring effect of bearing capacity was remarkable,the increase of deformation performance and energy dissipation capacity was notable;The overall seismic performance of all specimens was good.(4)The basic way and method to realize the spandrel failure mode of the existing masonry structure was as follows: to reinforce the bottom and cracked piers parts and to weaken or even not reinforce the spandrels parts,so that the failure mode of masonry structure could transfer from "strengthened" piers to "weakened" spandrels gradually and reasonably.