Rearch On The Control Of Story Lateral Stiffness And Shear Strength For Masonry Buildings With Frame And Seismic-wall In First Story

Because of easy construction and low cost, masonry buildings with frame andseismic-wall in first story is widely used in small citys and rural areas in China. Sincedifferences in material properties, the shear capacity, deformation capacity and energydissipation capacity between the lower frame and seismic-wall structure and the uppermasonry structure have great differences. Some masonry buildings with frame andseismic-wall in first story suffered varying degrees of damage or collapsed inWenchuan earthquake and Yushu earthquake. In order to research the reasonablefailure mode, factors of the failure modes and the method of implementation thereasonable failure modes, it is necessary to have a depth research from the view ofstiffness and strength.Firstly, this thesis put forward a reasonable failure mode for masonry buildingswith frame and seismic-wall in first story based on a summary and analysis of seismicdamage materials and existing research results; Secondly, this article proved that it isnecessary to control the yield mechanism and seismic performance of masonrybuildings with frame and seismic-wall in first story, after the analysis of three damagemasonry buildings with frame and seismic-wall in first story in Wenchuan earthquake;Finally,3D FEM models were established to do the elastic-plastic time-history analysisby ABAQUS finite element software, the influence of the different story lateralstiffness ratio between the second floor and the first floor(referred to “story lateralstiffness ratio” following) and the different story shear strength ratio between the firstfloor and the second floor(referred to “story shear strength ratio” following) for theyield mechanism and seismic performance of masonry buildings with frame andseismic-wall in first story were researched, a specific method was put forward tocontrol masonry buildings with frame and seismic-wall in first story for the reasonablefailure modes based on stiffness ratio and shear yield ratio.Based on the analysis and comparison, the conclusions were listed as follows:①The reasonable failure mode of masonry buildings with frame and seismic-wallin first story should be as follows: the lower frame and seismic-wall structure shouldbe the mainly deformation and energy dissipation position; the lower frame andseismic-wall structure don’t appear deformation which may create collapse, thecolumns and seismic-walls have enough capacity of resisting earthquake. ②The analysis of three damage masonry buildings with frame and seismic-wallin first story in Wenchuan earthquake showed that it is incomprehensive to control theyield mechanism and seismic performance of masonry buildings with frame andseismic-wall in first story. It is necessary to control the yield mechanism and seismicperformance of masonry buildings with frame and seismic-wall in first story from theview of stiffness and strength; in addition, the influence of frame filled wall on thestory lateral stiffness and shear strength of the lower frame and seismic-wall structurecan’t be ignored.③The story lateral stiffness ratio and shear strength ratio have significantinfluence on the yield mechanism and seismic performance of masonry buildings withframe and seismic-wall in first story. The greater of the story lateral stiffness ratio, themore seriously damage of the lower frame and seismic-wall structure, the less damageof the upper masonry structure; The greater of the story shear strength ratio, the lessdamage of the lower frame and seismic-wall structure, the more seriously damage ofthe upper masonry structure. In order to control the masonry buildings with frame andseismic-wall in first story achieve the reasonable failure mode this article proposed, thestory lateral stiffness ratio should be control in the range of1.25to2.00and the storyshear strength ratio should be control in the range of0.6to0.9.