Research On Hysteretic Behavior Of Unstiffened Tubular N-joints

Hollow section structures have been widely used in the world for their outstanding advantages.This paper introduces the classification of tubular joints detailedly,and summarizes the research status of unstiffened tubular joints and reinforced joints.In the article,it takes the steel truss structure of Beidaihe Train Station as a case study,performs finite element analysis and experiments research on hysteretic behavior of unstiffened tubular N-joint under cyclic load.It expatiates choice of finite element models,material capability,gridding partition,solution control of ANSYS and sample design,loading device,loading project,testing of experiments research,and compares with the results of finite element analysis and experiments,which validates that the finite element models are credible and experiment dataes are accurate.By observing the dilapidating phenomena of joints,it can draw the conclusion that the dilapidation modes of the four kinds of unstiffened tubular joint are coincident.The hysteretic behavior curves are drawn,then by analyzing and comparing with the four joints,designates that reinforcing measures like as reinforced with doublet plate and in-filled concrete,limiting plastic development of unstiffened tubular joints to a degree and debasing the hysteretic behavior and ductility,but which heightening the joints'rigidity,effectively enhancing the ultimate strength.It also has calculated joints'load capacity ratio,the first yield displacement and force and the ductile ratio,and made evaluating and comparing with them . Finally , the thesis makes a research on stress of joints'unstiffened area,which distributing is nonuniform,but symmetrical by the symmetry planar.