A New Study On The Seismic Performance Of The End Column-shear Wall Structure Of The Wall Is Added

With the development of China's economy and the improvement of the requirements for the seismic performance of buildings,the original buildings with poor seismic performance need to be strengthened in time.After the Wenchuan earthquake,in view of the huge losses caused by the destruction of many school buildings,the state upgraded the seismic fortification category of many public buildings,such as primary and secondary schools and kindergartens,from the general fortification category to the key fortification category in the building seismic fortification standard.Those existing primary and secondary school buildings are in urgent need of reinforcement because they do not meet the requirements of the new standard.In these buildings,multi-storey reinforced concrete frame structure accounts for a large proportion.The seismic grade of the frame is increased by one level due to the improvement of the fortification category.All the frame beams and columns need to be strengthened,and the workload is very heavy.If some shear walls are added to transform the frame structure into a frame shear wall structure,the seismic action is mainly borne by the shear wall,and the seismic grade of the frame in the frame shear wall structure does not need to be improved,so as to avoid the tedious work of strengthening all components.The frame shear wall structure formed by the reinforced wall is the key component to determine the overall seismic performance of the strengthened structure.It is very necessary to study the seismic performance of this component.There are obvious differences between the end column shear wall formed by the post added wall and the conventional cast-in-place end column shear wall: first,the joint surface between the new wall and the original beam column is a weak part,which may crack first after the earthquake,so that the end column and web can not work together completely;second,the existing beam column has borne the vertical load,but the new wall does not bear it.The initial internal stress of the two working together is very different.In this thesis,the seismic performance of end column shear wall formed by new wall is studied by numerical analysis method.The main work is as follows:(1)Using ABAQUS software,select the appropriate model and constitutive relationship,carry out the finite element analysis of the three-dimensional solid model of the test specimen in the existing literature,and compare the numerical simulation results with the measured results to verify the correctness of the selected model and constitutive relationship.(2)The failure mechanism of the wall and the distribution of the energy dissipation capacity of the shear column under the reciprocating loading state are analyzed,including the failure mechanism of the wall and the distribution of the energy dissipation capacity of the shear column under the horizontal compression state,and the failure characteristics of the wall under the reciprocating loading state are analyzed.The finite element simulation analysis is also carried out for the cast-in-place end column shear wall structure with the same size,and the analysis results of the two are compared.(3)According to the failure mechanism of finite element simulation analysis,the appropriate failure model is selected,and the calculation formula of compression and bending capacity of end column shear wall is put forward.The results show that:(1)In ABAQUS software,the cohesion model and Coulomb friction model can be combined to better simulate the inter facial bonding performance of new and old concrete.(2)With the failure of the bonding interface,the end column and web of the end column shear wall of the post added wall are separated into relatively independent members connected only by reinforcement.One end column is in full section tension,and the end column and web on the other side are in bending failure,while the whole cast-in-place end column shear wall is in bending failure of full section cooperative work.(3)Compared with the cast-in-situ end column shear wall members,the cracking load,yield load and peak load of the post cast-in-situ end column shear wall members are reduced to varying degrees,with the decrease ranges of 48.57%,27.15% and 14.60% respectively,among which the cracking load is reduced the most.(4)The end column shear wall specimen and the cast-in-place end column shear wall specimen of the post added wall with large height width ratio have good deformation capacity.The ductility coefficient of the two specimens is more than 3 and the ultimate displacement angle is more than 1 / 200,which can meet the design requirements.(5)In this thesis,a simplified analysis model and calculation formula of horizontal bearing capacity are proposed,and the calculation results are in good agreement with the numerical analysis results.