Experimental Research On Axial Compressive Performance And Shear Resistance Behavior Of Brick Walls Retrofitted By Dry-connected Steel Plate Rigid Frame

In the existing brick and concrete structure buildings,the main vertical load-bearing components are basically brick walls.Due to functional transformation or degradation of material properties,some brick walls need to be strengthened to improve their mechanical performance.Compared with different retrofitting methods,steel plate retrofitting method has the advantages of short construction period,simple retrofitting process and reversibility.In order to further optimize the retrofitting effect of steel plates and brick walls,this paper proposes a method for retrofitting brick walls with dry-connected steel plate rigid frame.The steel plate rigid frame can not only restrain the brick wall,improve its bearing capacity and deformation capacity,but also independently bear vertical and horizontal external forces as well as provide a second seismic line.In order to study the axial compressive performance and shear resistance behavior of the brick wall retrofitted by dry-connected steel plate rigid frame,this paper conducted experimental research and corresponding theoretical analysis.Firstly,the axial compressive performance test of 1 unreinforced brick wall,2 dry-connected steel plate rigid-frame retrofitted brick walls,1 brick wall retrofitted by steel strips and the shear resistance behavior test of 1 unreinforced brick wall,4 dry-connected steel plate rigid-frame retrofitted brick walls,1 brick wall retrofitted by steel strips were conducted.Based on the tests,obtained the failure characteristics,cracking and peak load,ultimate load,loaddisplacement curve and strain development of the steel plate.The parameters involved in the axial compressive test are thickness of the steel plate and the forms of reinforcement.The test results show that retrofit the brick walls with dry-connected steel plate rigid frames can effectively improve the axial bearing capacity and axial stiffness of the wall,delay the cracking,the axial peak load of the test piece in this paper is increased by about 40%～56%;improve the thickness of steel plate,the axial compressive bearing capacity increases as well as the ductility decreases;compared with the steel plate strip reinforcement method,the increase in axial compression bearing capacity is relatively close,but the effect of increasing stiffness is weak.The parameters involved in the shear test are thickness of steel plate,vertical load level and reinforcement forms.The test results show that the brick wall retrofitted by dry-connected steel plate rigid frame can effectively improve the shear bearing capacity and ducility,but it has little effect on the initial cracking of the wall.The peak load of the test piece in this paper is increased by about 50%～108%,the ductility is increased by about 44%～158%;with the increase of vertical load,the shear capacity and lateral rigidity increase,but the ductility decreases;increasing the thickness of the steel plate can increase the shear bearing capacity of the wall after reinforcement,but the lateral rigidity does not change much,the ductility decreases;compared with the steel strip reinforcement method,the increase in shear bearing capacity is relatively close,the ductility improvement effect is better,but the lateral rigidity improvement effect is weaker.On the basis of experimental research,the finite element model of brick wall retrofitted by dry-connected steel plate rigid frame was established by ABAQUS and modified to carry out expansion analysis to further study the influence of parameters such as the width of steel plate beam,the top constraint of steel plate rigid frame,and the bolt spacing.The analysis results show that the steel plate beam in the steel plate rigid frame has no obvious effect when the retrofitted wall is under vertical load;when the connection between the top of steel plate rigid frame and top beam is strengthened,the initial lateral rigidity increases,but the peak load does not change much;the bolt spacing has a greater impact on the bearing capacity of the retrofitted walls,the larger the bolt spacing,the easier the steel plate to buckle and the bearing capacity is lower.Finally,based on the existing steel plate buckling theory,calculation theory of steel frame and brick wall,combined with the experimental phenomena and the results of finite element analysis,the formula of axial compression and shear bearing capacity of brick wall retrofitted by dry-connected steel plate rigid frame is put forward and compared with the results of experiment to verify the accuracy of the formula,which provides reliable reference for the design of this reinforcement technology.