Experimental Studies And Finite Element Analysis On Seismic Behaviors Of Concrete-Filled Steel Plate At Ambient Temperature And After Exposure To High Temperature

As a new anti-lateral force structure,concrete-filled steel plate composite shear wall plays a great role in combining the cooperation characteristics of steel plate and concrete,which reduces wall thickness and increases using space and shows great improved bearing capacity and ductility compared to traditional reinforced concrete shear wall.There is very good prospects for engineering applications on this structure.Relevant test and theoretical research is still inadequate,especially existing studies usually focus on structures' mechanical properties under room temperature.Studies on structures after exposure to the fire(high temperature)are very few.In order to study the post-fire seismic behavior of this new shear wall structure,this paper conducted the following works and main conclusions are as follows:(1)three different shear-span ratio concrete-filled steel plate composite shear walls were tested under low cyclic loading at room temperature,comparing with the test of three shear walls with same parameters after one hour high temperature.Results show that there is huge influence on the effect of high temperature on the damage form of specimens,local buckling deformation on room temperature specimen plate appears smaller and later,which appears mostly on th bottom of the front and back wall and bottom of both sides.Local buckling deformation of specimens after exposure to high temperature appears earlier,with bigger deformation scaling up to the middle of the wall.The shear span ratio of 1.0 and 1.5 specimens show the shear destruction,with shear span ratio of 2.0 specimen showing bending damage.(2)The ultimate bearing capacity of the post-fire specimens,with shear span ratio ranged from 1.0 and 1.5 to 2.0,was reduced respectively by 23.8%,19.6% and 11.3%,compared to the specimens tested at room temperature.AT the same time,the limit displacement of the post-fire specimens was reduced respectively by 48.3%?37.2%?24.9%,compared to the specimens tested at room temperature.Limit displacement and ductility of post-fire specimens increases compared to the specimens tested at room temperature,The ultimate bearing capacity and stiffness of post-fire specimens decreases compared to the specimens tested at room temperature.Seismic performance of specimens shows a certain degree deterioration,but still performs well in general.(3)Results indicate that whether damaged by fire or not,stiffness and ultimate bearing capacity of specimens reduces with the increase of the shear span ratio,ultimate displacement and ductility and energy dissipation capacity increases with the increase of the shear span ratio.Compared to specimens tested at room temperature,the smaller of the shear span ratio,the bigger of the drop of the ultimate bearing capacity,ductility and energy dissipation capacity of post-fire specimens,which shows bigger degree of degradation of seismic performance.(4)Numerical simulation on tests under low cyclic loading of post-fire specimens and specimens tested at room temperature was conducted,with six ABAQUS finite element models established.The results show that the finite element analysis matches well with the test results on specimen failure pattern and hysteresis curves and skeleton curves,which verifies the effectiveness of finite element modeling method and provides the basis for further parametric analysis.(5)Based on this finite element model,fifty-four ABAQUS finite element models was established,which aims to investigate the impact of the change of axial compression ratio and the thickness of the steel plate and wall thickness and diameter of toggle pin on the ultimate bearing capacity of the pecimens.The results show that the increase of the parameter of axial compression ratio,thickness of steel plate and the wall thickness leads to the increase of ultimate bearing capacity,which results in a bigger increase of ultimate bearing capacity of specimens tested at room temperature than post-fire specimens.For specimens of different parameters,there is different reduce of ultimate bearing capacity of post-fire specimens than specimens tested at room temperature.The bigger of the axial compression ratio,thickness of steel plate and the wall thickness,the bigger of the drop of the ultimate bearing capacity of specimens after exposure to high temperature.