Numerical Analysis And Design Method Of Loaded Steel Columns Reinforced With CFRP

Due to its superior mechanical properties,the steel structure is becoming a strategic industry full of vitality in the modern society with rapid economic development and ecological civilization construction.As of the end of 2016,China’s steel production ranked first in the world,but only about 5% was used to build steel structures and bridge steel structures.China’s steel construction and bridges account for a much smaller proportion of all structures than developed countries.As a structural system with obvious advantages,steel structure has been widely used in engineering constructio n.However,with the passage of time,the steel structure may be degraded due to factors such as corrosion,wear,increased load,accidental damage or over-limit of building structure life.As a new type of composite material,CFRP has become an important research field in the field of civil engineering due to its superior material properties.The research work and results of this paper are as follows:(1)The orthogonal experimental design is used to optimize the experimental design of CFRP-reinforced steel column compression test.The CFRP-reinforced composite steel column test is carried out.The eccentricity,CFRP layer number and slenderness ratio are considered according to the cross-section of steel column.The effect on the overall stability of the pressurized steel tubular column.The test results show that the failure mode of the composite steel tube column is the overall instability,and the yield of the cross-section of the column is firstly affected;the CFRP adhesion layer has a certain effect on the ultimate bearing capacity of the steel tube column.(2)Using the large-scale finite element analysis software ABAQUS,reasonably select the material constitutive relation,determine the unit type,contact treatment and mesh division,establish the nonlinear finite element calculation model of CFRP-confined steel tube column under load,and the test results comparing.The finite element calculation results show that the ultimate bearing capacity and load-deflection curve are basically consistent with the experimental results,and the ultimate bearing capacity is not much different,which verifies the validity of the finite element analysis model and lays a foundation for later research.(3)The orthogonal numerical analysis of the ultimate bearing capa city of CFRP-reinforced square steel tubular column and round steel tubular column is carried out.The parameters such as loading eccentricity,CFRP layer and member slenderness ratio are compared and analyzed.The degree of influence of column stability is: eccentricity,slenderness ratio,and number of CFRP paste layers.According to the orthogonal design numerical analysis conclusion,the stability coefficient of CFRP strengthened steel tubular column was fitted and analyzed.The polynomial linear regression fitted by mathematical analysis software MATLAB was used to predict the change of bearing capacity and the overall stability correction coefficient.The existing literature models underestimate the bearing capacity of CFRP-reinforced steel column.Based on this,the theoretical calculation formula of the modified CFRP-reinforced eccentric compression members is proposed.