Study On Explosion Performance Of Masonry Infilled Wall Reinforced By BFRP-FRCM

In recent years,the international situation was complex and the geographical conflicts were escalating.All kinds of buildings in the city would face various terrorist attacks and sudden explosions.In addition,with the rapid development of Chinese economy and urbanization,accidental explosion accidents such as fuel gas,fireworks and firecrackers occurred frequently,and the damage to buildings could not be ignored.Masonry infilled walls were widely used in existing buildings.The tensile strength of masonry walls was low.Once masonry infill walls were destroyed by explosion loadings,explosion-induced splashed fragments will cause injuries and equipment damage.This study proposed applying basalt fiber mesh-fiber reinforced cement matrix(BFRP-FRCM)composite layer to improve the explosion performance of masonry infilled walls.Then the reinforcement effect of BFRP-FRCM enhancing the masonry infilled walls under explosion loadings was experimentally studied.And the enhancing mechanism was explored by analyzing proportional distances and reinforced schemes influencing the failure mode,fragment distribution,displacement response,reflected overpressure,acceleration response and damage assessment.The finite element software was used to simulate the test results.The specific work and conclusions were as follows :(1)BFRP-FRCM reinforcement could effectively reduce the explosion-induced damage of the masonry walls.Blasting surface reinforcement could reduce the range of the mortar joint shedding,the number of explosive fragments and the distance of fragments from the masonry wall,however,the residual displacement of the masonry wall was still large.Reinforcement of the back blasting surface reinforcement could reduce the displacement response of wall more effectively,and there was no visible fragmentation.Double surface reinforcement significantly improved the compressive bearing capacity and flexural bearing capacity of the masonry wall,both the peak displacement and residual displacement of the wall were the smallest.On the other hand,even with the decrease of the proportional distance,only local deformation and small cracks appeared in the center of the masonry wall after double surface reinforcement,and did not occur the debris scattered.At the same time,BFRP-FRCM reinforcement significantly reduced the peak acceleration of masonry walls.The reduction effect of single-sided reinforcement on the peak acceleration is roughly the same,and the peak acceleration of doublesided reinforced masonry walls is the smallest.(2)By using LS-DYNA software,a separate refined numerical model of masonry wall was established,and the Load Blast algorithm was used to simulate.The numerical simulation results can accurately reflect the failure mode of unreinforced masonry wall and reinforced masonry wall.The test results of the displacement time history curve of the specimen were in good agreement with the numerical simulation results.The trend of the simulated reflection overpressure curve was basically consistent with the test results,and the error was within the allowable range of the explosion test.The influence of FRCM compressive strength and proportional distances on the dynamic response of masonry wall was considered.Increasing FRCM compressive strength had little effect on the peak displacement of masonry wall.The peak displacement of the single-sided reinforced masonry wall increased with the decrease of the proportional distance,and back blasting surface reinforcement could reduce the displacement response of masonry wall more effectively.(3)The influence of different reinforcement schemes on the explosion performance of masonry infill walls was analyzed by introducing impulse and strengthening parameters.Under the same proportional distance,the reflected overpressure and impulse of the unreinforced wall and the reinforced wall were roughly the same,but BFRP-FRCM reinforcement could improve the strengthening parameters of the masonry wall.By analyzing the failure mode of the unreinforced masonry wall and calculating the maximum bearing rotation angle and residual displacement rotation angle of the reinforced masonry wall,the damage degree of the masonry wall after the explosion was evaluated.The results showed that compared with the unreinforced masonry wall,the damage degree of the masonry wall reinforced by BFRP-FRCM is reduced.The strengthening parameters of the double-sided reinforcement were the largest,the maximum bearing rotation angle and the residual bearing rotation angle were the smallest,and the reinforcement effect was the best.