Research On Bearing Capacity Behavior Of Split T-steel Compression Members Based On OIC

In recent years,with the development of steel structure,T-section steel can be used to replace the double angle steel in steel truss as the upper and lower chord,at the same time,it makes the structure simple and has better economic benefits.In the application of T-section steel,the main stress form is axial compression or shear center compression.At present,most of the steel structure design codes at home and abroad have some shortcomings in the calculation of member bearing capacity.For example,in the design of bearing capacity in our country,the interaction between plates is neglected,and strain hardening is not considered.The European Code for design of steel structures adopts the method of section classification to design members,cross-sections are divided into four classes according to different aspects ratios of plates.There exists a"jumping"discontinuity in the design process of bearing capacity of section between class II and III.The OIC(overall interaction concept)method is based on the improved aryton Perry formula,which is not only perfect in theory and simple in application,but also can effectively deal with the drawbacks in the above specifications.At home and abroad,most of the OIC method is applied to the closed section,and the theory of expanding it to the section of T-shaped steel members is still blank,which needs further study.In this paper,the large-scale general software ABAQUS is used to simulate the buckling capacity of T-section steel under axial and shear compression,and the factors such as material strain strengthening,initial geometric defects and residual stress are considered.The accuracy of the model is verified by the test data,and the variable parameters that may affect the ultimate bearing capacity of the member,such as yield strength f_y,section height width ratio H/B,web flange thickness ratio t_w/t_f and load position,are further analyzed.The results show that the yield strength of material has no significant influence on the normalized ultimate bearing capacity of T-section steel under axial compression and shear center compression,with the maximum difference of 6%.Therefore,when fitting the OIC recommended formula,it is not considered.The H/B ratio of section height to width has significant influence on the T-section steel,and the main influence area is in the middle of the normalized slenderness ratio.At this time,the buckling modes and the sensitivity to defects of member are different.The influence of web to flange thickness ratio t_w/t_f is similar to that of H/B.the influence of H/B and t_w/t_f should be considered simultaneously in the fitting of OIC recommended formula.When the load is moved from the section centroid to the section shear center,the maximum reduction of the ultimate bearing capacity of the member is 75.84%.Therefore,moving the action line of the pressure from the centroid to the shear center axis will lead to the insufficient stable bearing capacity of the member.This needs to be paid attention to by engineering designers.Based on the results of numerical model calculation,this paper puts forward the OIC formula for splitting T-section steel compression members under axial compression and shear center compression,and compares it with Chinese code,American design code and European design code.Finally,the accuracy of the proposed OIC formula is verified by the existing experimental data.It can be seen that the proposed OIC formula is better than other design methods in terms of continuity or accuracy.