Hysteretic Behaviour Of Square Hollow Section(SHS) Brace-H-shaped Chord T-joints

H-shaped steel performs well in easily fabricated and flexibly designed with surfaces of the flanges parallel to each other.When it is as a chord,its web can provide sufficient axial stiffness under axial loads from the end of brace,so H-shaped steel is often used with other types of hollow section steels in many long-span structures.In another hand,frequent earthquakes in the world pose a threat to buildings and structures,how the joint with Hshaped steel performs or whether the behaviour of the joint with reinforcement can be strengthened after an earthquake is still a question.Hence,the research of these aspects is needed.In this thesis,the hysteretic behaviour of SHS brace-H-shaped chord tubular T-joints with or without stiffener plate was experimentally and numerically investigated.Firstly,six specimens with same geometric properties of chord and different geometric properties of brace were fabricated.Three of them were tested without reinforcement and the others were tested with lateral stiffener plates reinforced to study the hysteretic behaviour.In the cyclic loading test,hysteretic curves,failure modes,skeleton curves and energy dissipations of joints were analyzed.The results revealed that comparing the specimens with reinforcement,the specimens without reinforcement showed less area enclosed by hysteretic loop,less capacity of energy dissipation,but almost the same ultimate capacity.Furthermore,based on the constitutive relation of the steel,the definition of welding and the set of reinforced plates,the finite element(FE)models of SHS brace-H-shaped chord T-joints were built in FE software ABAQUS.The FE models were validated against the experimental data obtained from the cyclic loading test by comparing their hysteretic curves,energy dissipations and failure modes.After the verification of FE models,a comprehensive parametric study was conducted to investigate the influences of various parameters hysteretic behaviour.The abovementioned parameters included brace/chord flange width ratio,brace/chord flange thickness ratio and the number of reinforced plates,which might have an influence on the hysteretic behaviour of SHS brace-H-shaped T joints.