Study On Seismic Behavior Of The Short-Limb Wall Of Concrete-Filled Steel Tube

The short-limb wall of concrete-filled steel tube(simply called SLW-CFST)is a new form of composite components.It is composed by U shaped steel of different size by welding connection and the inner of steel tube bundle is filled by casting concrete.This kind of new components have some advantage:The thickness of steel is thin;the construction speed is fast;it is easy for standardized production;it can be fabricated quickly.Compared with the steel tube bundle concrete shear wall,the space layout is more flexible and it can be used in building with concrete filled steel tube special-shaped column and shear wall.Therefore,studying SLW-CFST has certain engineering application value.To analyze seismic performance of SLW-CFST,a low cyclic loading experiment with two pieces of SLW-CFST was conducted.Through the experiment seismic performance of the components were obtained,and the hysteresis curves,skeleton curves,carrying capacity,energy dissipation were analyzed.Results show that the damage phenomenon of SLW-CFST under low cyclic loading were plate buckling and concrete crushed damage at the bottom,specimens have good ductility and energy dissipation capacity;As the axial compression ratio increases,bearing capacity and ductility of the member reduced in a certain degree.The viscous damping coefficient of component is 0.25 to 0.3 and the viscous damping coefficient is larger when the axial compression is less.This paper created the finite element model of SLW-CFST by ABAQUS and the results are consistent with experiment.On this basis,the parametric analysis of SLW-CFST was conducted by changing the steel plate thickness,concrete strength,steel strength,axial compression ratio,shear span ratio and size of u-shape,then analyzed the parameters influence on the seismic performance of SLW-CFST.The results show that the thickness of steel plate improve the bearing capacity of specimens most effectively;When concrete level or the steel plate thickness increases,the ductility of the member increases;When axial compression ratio increases,the ductility reduce,the viscous damping coefficient is less;When the axial compression is little,the influence of axial compression ratio on the bearing capacity of the specimens is not big,but when the axial compression ratio is greater than 0.7,the bearing capacity of the component will reduce more than 15%.According to the strain measured by strain gauge in test process,it verified the cross-section strain of SLW-CFST accord with plane cross-section assumption.Based on the research achievements of relevant scholars and superposition theory,the bearing capacity of normal section of SLW-CFST formula is deduced,the calculated results with the experimental results and finite element results are compared and agreed well.On the basis,the formula for calculating the ultimate bearing capacity was given.This paper created finite element models of concrete-filled steel tube column,special-shaped concrete-filled steel tube column and concrete composite shear wall.These models have same section length with SLW-CFST and the seismic performance is compared.Analysis shows that as the limb section length of concrete-filled steel tube one-word members decrease,the energy dissipation capacity of the components decreased to a certain extent;L-shaped and other special-shaped members have better seismic performance than the cross-section of a word-shaped.Through engineering experience and combined with the relevant specification,this paper presents some advice for the design calculation of SLW-CFST and engineering application.