The Research On The Seismic Ductility Performance Of Steel Columns With High Axial Compression Ratio

The construction of urban rail transit in China has entered a period of rapid development,especially in the proportion of subway construction.Because of the characteristics of the structure of the urban track itself,a large number of high axial-pressure ratio frame columns are used.Under the action of earthquakes,the destruction of the columns with high axial-pressure ratios will be more serious,especially with the damage of the column legs.Therefore,the seismic-ductility performance of the column with high axial compression ratio is a difficult problem that must be overcome in the construction of urban rails,especially in the construction of subways.In order to improve the safety of the structure,at present,in the existing urban rails in China,especially in the construction of underground stations,steel reinforced concrete columns are widely used instead of ordinary reinforced concrete columns.The transport of steel reinforced concrete column also makes the damage of high axial pressure ratio column relatively less.However,when the column is subjected to a large vertical load,its deformation ability will be reduced.Therefore,it is necessary to study the ductility of steel reinforced concrete columns under high axial compression ratio.The main work of this article includes the following points:(1)Through the collection and analysis of domestic and foreign research results data,and the seismic damage investigation of frame columns,the axial compression ratio,shear span ratio,stirrup ratio,stirrup form,steel content,concrete strength,and studs were summarized.Influence of Influencing Factors on Seismic Performance of Steel Reinforced Concrete Columns.This paper mainly studies the effect of high axial compression ratio on the seismic behavior.(2)The reduction coefficient and coefficient of variation of each concrete strength grade are obtained by linear interpolation,and the calculation relationship of the axial compression ratio of ordinary reinforced concrete columns under each concrete strength grade is calculated,and the design axial compression of the steel reinforced concrete column is calculated.The relationship between the ratio of the ratio to the test axial pressure and the required vertical load during the test loading.(3)Two steel reinforced concrete columns with a high axial compression ratio of 0.57 and 0.7 were designed and subjected to a pseudostatic loading test(low-cycle reciprocating loading test)to obtain the hysteresis curve and skeleton curve of the steel reinforced concrete column.The equivalent viscous damping coefficient and work ratio index of its energy consumption index were calculated by the hysteresis curve;the ultimate displacement and yield displacement were obtained from the skeleton curve,and the displacement ductility coefficient of the seismic ductility performance index was obtained.(4)According to the specification,the plastic damage constitutive equation of concrete is calculated,and ABAQUS is used to numerically analyze the steel reinforced concrete column with the axial ratio of 0.57 and 0.7,and the numerical analysis results are fitted to the experimental results;The axial compression ratio was expanded to 0.8,0.9,1.0,1.1,1.2,and 1.3.Through the analysis of variable parameters,the energy dissipation performance and seismic ductility properties of steel reinforced concrete columns under high axial compression ratio were obtained.