Research On Pseudo Static Test And Design Method Of Precast Reinforced Concrete Masonry Shear Walls

Recently,with the accelerated urbanization process in China,building industrialization and housing industrialization have become the latest development trends of the construction industry.The precast structure system,with the advantages of high mechanization,fast construction speed,low cost,strong quality stability,low energy consumption,and low pollution,has become an important development direction of China's construction industry.Meanwhile,the reinforced concrete masonry shear wall(CM shear wall in short)structural system,with the advantages of good seismic performance,low cost,energy conservation and environmental protection,has been widely used in mid-rise and high-rise buildings.However,CM shear walls have some shortcomings caused by the site operation of construction,such as the cleaning-hole blocks for the connection of vertical rebar and the cleaning of extra mortar,and the weakness caused by the concentrated connection of the vertical rebar at the bottom layer.Under this background,the precast reinforced concrete masonry shear wall(PCM shear wall in short)structure system,which owes the advantages of the above two structural systems,can avoid the shortcomings of CM shear wall through industrial production of prefabricated components and assembly hoisting technology and is very meaningful to the development of China's construction industry.However,the PCM shear wall structural system is currently in its infancy,and a great many of studies are urgently to be carried,such as the research on the seismic performance of the PCM shear wall components and structures,and the seismic design method of PCM shear wall.Thus,this thesis carried out the research on the seismic performance and the design theory of PCM shear wall.The main contents are summarized as follows:In order to study the seismic performance and stability of PCM shear wall,4groups of 8 PCM shear walls and 2 groups of 4 CM shear walls were designed and tested under vertical loads and horizontal low cyclic loads.The failure modes of PCM shear walls and CM shear walls were summarized.The effects of axial compression ratio,the distribution of vertical reinforcement and the prefabrication construction technology were analyzed.The results showed that the PCM and CM shear walls had similar flexural failure mode,except that the elimination of cleaning-hole blocks delayed the cracking of blocks and improved the flexural capacity of the PCM shear walls.The flexural capacities of the PCM and CM shear walls improved obviously with the increase of axial compression ratio,while the capacity of the PCM shear walls with the vertical rebar concentrated at the end of the wall increased slightly compared with the specimens with even distribution of vertical rebar.Based on the experimental analysis,the PCM and CM shear walls both exhibited relatively good seismic performance stability.The normalized four-linear stage envelope curves of the PCM and CM shear walls were established according to the test.The results indicate that the PCM and CM shear walls had similar stiffness degradation rules,and both exhibited good deformation capacity.The thesis established the hysteretic model of the PCM shear wall,and the calculation results were in good agreement with the experimental results.The results reveal that the PCM shear wall had better energy dissipation capacity than those of the CM shear wall under the elasto-plastic conditions.Based on general software ABAQUS,the finite element models of the PCM shear walls were established for the simulation of the pseudo-static test.The thesis conducted a series of finite element studies with the parameter variations on the seismic performance of the PCM shear walls.The results showed that the increasing of axial compression ratio and the decreasing of the shear span ratio had better influences on the increasing of the flexural capacity of the PCM shear walls,than that of the parameters of the vertical rebar,such as the concentrated distribution at the ends,the increasing reinforcement ratio and tensile strength.The decreasing of the shear span ratio also had a great effect on the increasing of the initial stiffness of the PCM shear wall.Besides,the 10% increasing of the compressive strength of the grouted masonry improved the bending capacity of the PCM shear walls by about 5%under the fixed axial compression ratio.This thesis conducted a comparative study of the codes for design of masonry structures in China,America and Europe.The calculation methods of the strength of the precast grouted masonry and the flexural capacity of the PCM shear wall were proposed and verified by the results of the quasi-static test,proving that the calculation results were in good agreement with the test results.The reliabi lity indexes of the flexural capacity of the PCM shear walls were calculated by Monte Carlo method,and the results proved that the structural reliability of the flexural capacity of the PCM shear wall was in accordance with the specifications.