Experimental Study On Seismic Performance Of PEC Cross-shaped Columns

Partially encased concrete composite column(PEC column)is a new type of composite structure.It takes the advantage of steel and concrete including high bearing capacity,good energy dissipation capacity and good fire resistance.The prefabrication and assemblability of PEC structure are superb,and it is more energy saving and environmental friendly than traditional materials,so the future of the market is broad.At present,the study of PEC structure in China is not perfect.In this paper,structural test,numerical simulation and theoretical analysis are combined to explore the seismic performance of PEC column.In this paper,the seismic tests of three groups of PEC columns under low frequency reversed cyclic quasi static loading are carried out.The purpose is to study the seismic performance of PEC structure including failure form,hysteretic performance,ductility and so on.The results show that the main failure phenomena of the PEC cross-shaped column are the concrete falling off at the bottom of the column,the strong axial flange buckling,the exposed or bent tie-bar,and the web buckling.The hysteretic curves of all specimens are full and fusiform,indicating that the PEC cross-shaped column has good mechanical performance.With the increase of axial compression ratio,the initial stiffness of specimens increases,the ultimate bearing capacity increases,but the ductility decreases.At the same time,under the same loading level,the seismic energy dissipation performance of the specimens with higher axial pressure ratio is better,but since the peak load is reached earlier,the loading level decreases,resulting in the total energy dissipation decreases.The finite element simulation analysis was carried out by ABAQUS,and the simulation results were compared with the experimental results to verify the validity and reliability of the finite element software simulation results.Based on this,the characteristic values and ductility coefficients of skeleton curves of PEC cross-shaped columns under different coaxial pressure ratios and different section steel ratios were studied.The results show that the increase of axial compression ratio can increase the peak load of the specimens within a certain range,but when the axial compression ratio exceeds 0.6,the peak load of the specimens under tension will decrease significantly.With the increase of column flange thickness,the ultimate bearing capacity of specimens increases slightly,but the ultimate displacement decreases.As the thickness of the column web increases,the ultimate bearing capacity of the specimen decreases slightly,but the ultimate displacement increases greatly.The increase of flange and web thickness reduced ductility coefficient.