Study On The Influence Of Openings On The Seismic Performance Of Self-Insulating Inner-Framed Bearing Walls

The traditional masonry structure still has the problems of high energy consumption and poor seismic performance.From the perspective of integration of earthquake resistance and energy conservation,the research group proposed a self-insulating inner-framed bearing walls(SIBW)structure system.Due to the needs of building functions,all kinds of bearing masonry walls with door openings and window openings widely exist in the building structure,and studied the influence of the openings on the seismic performance of the SIBW and established.It is very important to use a unified method to calculate the seismic and shear capacity of the SIBW.Based on the seismic test research of the unopened hole(specimen W1)and window opening SIBW(specimens W2 and W3)carried out by this research group,two more SIBW with open doors are designed and manufactured Walls(specimens W4,W5)and subjected to low cycle load test under vertical load,through comparative analysis and theoretical research of the test results,the following main research results have been obtained:1.The influence of the door opening on the seismic performance of SIBW is studied(1)W4,W5 and W1 have higher seismic bearing capacity(W1 is higher),and the final failure mode is to form a stepped diagonal crack in the area surrounded by the inner-framed.When the wall reaches failure,the bearing capacity drops not significantly.It can be calculated that the ductility coefficients of the three test pieces are 2.95(unopened specimen W1),3.55(center door opening specimen W4),and 3.67(eccentric door specimen W5),all showing good performance.Ductility and deformation ability,failure mode are also ductile failure.(2)The door opening has a significant effect on the hysteretic curve,skeleton curve,stiffness and its degradation,energy consumption capacity of the SIBW.Taking the ultimate load as an example,the ultimate load of W4 and W5 is reduced by 40.29% and 36.51% respectively compared with W1,which shows that the door opening reduces the bearing capacity of the test piece and destroys the integrity of the wall and the transfer path of the force.(3)For the SIBW,the position of the door opening has no obvious influence on the bearing capacity and hysteretic curve of W4 and W5,the former is 5.55% higher than the latter,and the yield load and ultimate load are 7.22% and 5.96% lower,respectively.The reason is that the arrangement of the concealed framed of W4 and W5 in the later stage is basically the same;however,the offset of the door opening leads to the skeleton curve asymmetry affects the safety reserve capacity of the wall,reduces the area of hysteresis loop,and has a negative impact on the seismic resistance of the wall.2.The influence of window holes on the seismic performance of SIBW is studied(1)The failure characteristics of W2 and W3 with window openings are similar.The failure sequence starts from the spandrel walls and then develops to the wall between the windows.The spandrel walls ties the first seismic defense line of the load-bearing wall of the self insulation concealed skeleton of the window opening.The width of the wall between the windows has a significant impact on the hysteretic curve,skeleton curve,stiffness,degradation and energy consumption capacity of the wall.The wall between the windows bears the seismic ultimate bearing capacity,but the influence of the spandrel walls on the seismic performance of the wall with window opening should not be ignored.(2)Comparing the test results of W4 and W2,it can be seen that the hysteretic curve,skeleton curve and energy dissipation capacity of W2 with spandrel walls are significantly different from those of W4 with the same opening width;through the study of the established calculation formula of seismic bearing capacity,it is found that the spandrel walls has a direct and indirect effect on the side bearing capacity of the wall.3.The unified calculation formula of anti-seismic and shear capacity of SIBW is established(1)Based on the failure process of five SIBW,combined with the analysis of hysteretic curve,skeleton curve and the mechanical properties of blocks and reinforcement at the same location,the failure process of the wall is divided into three stages: joint work,transition and weak frame,which lays a simplified foundation for the establishment of the shear bearing capacity calculation formula of the new wall.(2)Based on the equivalent elastic plate model,the crack load calculation method of the self insulation dark skeleton bearing wall is established by introducing the modification of the opening rate and the constraint coefficient of the concealed framed;based on the shear resistance mechanism idea,the rigid frame diagonal strut model is proposed,and the calculation method of the wall ultimate load is established by the modification,and the accuracy of the calculation method is high,which can meet the needs of engineering application.In conclusion,through the combination of physical test and theoretical analysis,this paper studies the influence of the portal on the seismic performance of the SIBW,the working mechanism of the spandrel walls and the wall between the windows participating in the earthquake resistance is clarified,establishes the unified calculation formula of the seismic bearing capacity of the wall,and provides help for promoting the integrated development of the seismic energy saving of the masonry structure in villages and towns.