Finite Element Analysis On Hysteretic Behavior Of CHS Members

ABSTRACT:As the frequent earthquakes happened worldwide recently, circular hollow section (CHS) members and its complicated structure system still could be damaged in the severe earthquake. It showed that the dynamic failure mechanism of such simple members and complicated structures construct has still not been thoroughly understood. Also, the corresponding design criteria and technical measures need to be improved. Therefore, In this paper, the hysteretic behavior of CHS members, as well as its influence factors, was studied by means of numerical analysis with ABAQUS software.This paper includes the following jobs:(1)Numerical analysis models of CHS members were built with S4R shell element, and reasonable meshing method was identified by comparing the calculation results of models with different mesh size. The results were validated by experiments of the classic references. By comparing the test results with those of the analysis, it is verified that the finite element method adopted in the paper is reasonable and can be used in hysteretic behavior analysis of CHS members under cyclic bending.(2)Considering the global and local initial geometric imperfections, with loading system suggested by ECCS, numerical analysis models were built, which for hot-rolled seamless and cold-formed welded CHS members under constant compression and cyclic bending. Used members’diameter is219mm,thickenss are6mm、8mm、10mm、12mm,slenderness ratios are30、60、90,axial compression ratios are0.2、0.4、0.6.According to the nonlinear calculation results for members, ultimate load-carrying capacity, ductility coefficient, energy dissipation coefficient and the number of cycles at fracture of CHS members were obtained. The influence of parameters such as diameter-to-thickness ratios, slenderness ratios as well as axial compression ratios on the hysteretic behavior of the members has been discussed. With the increase of diameter-to-thickness ratios, slenderness ratios as well as axial compression ratios, the ultimate load-carrying capacity and ductility of the members decrease, and has different influence on energy dissipation capacity.(3) With damage-based hysteretic model of thin-walled pipe-section steel bridge piers as reference, this paper regressed relational expression for parametric analysis results, on the basis of parameter analysis results. Therefore, in this paper, hysteresis model which is used for simulating the CHS members were proposed and be verified that it could be used in advanced research.