Research On Eccentric Compression Bearing Capacity Of Slender Steel Reinforced Concrete Columns With Monosymmetric Cross-shaped Steel

In order to meet the building requirements of flush facade,the structural design of steel reinforced concrete column mostly adopts the joint structure of beam column flush,which leads to the eccentricity of the center line of beam and column.In order to meet the eccentricity setting of steel reinforced concrete beam,the medium steel of steel reinforced concrete column is asymmetric.At present,there are few researches on composite columns with asymmetric steel at home and abroad.The existing researches mainly focus on T-shaped and L-shaped steel reinforced concrete composite columns,but the research on steel reinforced concrete columns with monosymmetric cross-shaped steel has not been involved.Based on the test,finite element analysis and theoretical analysis,this paper studies the eccentric compression performance and bearing capacity calculation method of slender steel reinforced concrete columns with monosymmetric cross-shaped steel.The main contents and achievements of this paper are as follows:The main test parameters are cross steel eccentricity and load eccentricity,and the influence of them on the eccentric compression performance of the composite column is studied.The test results show that: the specimen with load eccentricity of 0.2 has small eccentricity failure,and the specimen with load eccentricity of 1.0 has large eccentricity failure;the strain of concrete and section steel in the midspan section of the specimen basically conforms to the assumption of plane section;within the range of test parameters,the eccentricity of cross section steel increases,and the ultimate bearing capacity and deformation capacity of the specimen decreases slightly with positive eccentricity;the ultimate bearing capacity and deformation capacity of the specimen decrease with negative eccentricity The results show that the eccentricity of cross section steel has little effect on the eccentric compression performance of specimens with small eccentric compression failure,and the ultimate bearing capacity of specimens with large eccentric compression failure slightly improves with the increase of eccentricity of cross section steel;the initial stiffness and ultimate bearing capacity of specimens decrease with the increase of load eccentricity.Based on the test,the ABAQUS finite element model is established.According to the strength of stirrup and section steel on the concrete,the section concrete of slender steel reinforced concrete columns with monosymmetric cross-shaped steel is divided.The simulation results are compared with the experimental results to verify the rationality of the model.On this basis,the load lateral deformation curves of slender steel reinforced concrete columns with monosymmetric cross-shaped steel are obtained by changing the parameters of the finite element method,and the influence of the concrete strength,steel content,stirrup spacing and slenderness ratio on the eccentric bearing capacity is analyzed.Based on the assumption of plane section and the second-order effect,the limit equilibrium method is adopted to calculate the normal section bearing capacity of composite columns,which can not only keep the existing code form,but also consider the eccentricity of cross section steel.The monosymmetric cross-shaped cross section steel is converted into H-section steel,and the code JGJ138-2016 is used to calculate the eccentric bearing capacity of the converted section specimens.The calculation results are more conservative than the test results.The eccentric bearing capacity of the specimens calculated by the method proposed in this paper is in good agreement with the test values,which can be used for the engineering design of this kind of composite columns.