Seismic Behavior Of Light Gauge Steel Reinforced EPS Concrete Shear Walls

Light gauge steel-EPS concrete shear wall is a new form of structural member composed of light gauge steel encased by lightweight expanded polystyrene(EPS)concrete.Compared with the traditional reinforced concrete shear wall,light gauge steel-EPS concrete shear wall has great advantages in features such as lower self-weight and industrialized construction way,which would be used as structural element in low-rise and mid-rise building.The seismic performance of light gauge steel-EPS concrete shear wall was studied in the paper and the main research work and achievements are as follows:(1)The stress-strain behavior of EPS concrete was investigated based on the axial compression tests of twenty-four specimens divided into six series.Then,the effect of dry density and curing age on the compressive strength as well as peak strain and stress-strain curve were observed.Finally,a stress-strain model for EPS concrete was proposed and its applicability was discussed based on the test curves.(2)According to the pull-out tests of twenty specimens,the bond-slip characteristics between light gauge steel and lightweight EPS concrete were investigated.The bond-slip mechanism was studied with the parameters including concrete strength,bonded length and cover thickness.Based on the test results,a three-stage bond-slip model was proposed to represent the behavior of light gauge steel in EPS concrete.(3)In order to study the seismic performance of light gauge steel-EPS concrete shear wall,nine specimens with the different aspect ratio and designed axial compression ratio were tested under cyclic reversed loads.The failure mode,hysteretic behavior,ductility and energy dissipation performance of those composite walls were analyzed.The test results indicated that the failure mode is different from that of the traditional reinforced concrete wall and similar with the infilled wall in frame.The vertical cracks developed through the wall and the hysteresis curve showed significant pinch phenomenon owing to the slip between light gauge steel and EPS concrete.(4)A refined nonlinear finite element model was established to analyze the behavior of the light gauge steel-EPS concrete shear wall under cyclic reversed load.Then the loading mechanism of the shear wall and the influence of EPS concrete strength,the horizontal reinforcement ratio and boundary element on the loading capacity were studied by finite element analysis(FEA).(5)Based on the test results and FEA,the rational models for evaluating the shear and bending strength of the shear wall were established on the equivalent compressive strut model and plane cross-section assumption,respectively.Then,the formulas of shear and compression-bending capacity were derived,which were verified and showed good agreement to the test results.(6)The restoring force model was proposed for the light gauge steel-EPS concrete shear wall.A simplified tri-linear model was presented to describe the skeleton curve and a hysteretic rule was summarized to simulate the pinch effect of the hysteresis curve.Then,the restoring force model was verified by comparing the energy dissipation capacity and agreed well with test results.