Research On Hysteretic Behavior Of Cruciform Diaphragm Welded Joint

ABSTRACT:Cruciform diaphragm welded joint has been put into use in large-span spatial structure, but research on hysteretic behavior of this kind of joint is still in the initial stage. Based on this, this paper carries out the research of cruciform diaphragm welded joint in the following aspects:Firstly, two batches smooth and notched specimens which were taken from Q235B hot-rolling seamless pipe commonly used in large-span structure were unidirectional tensile tested and cycle loading material tested, combining with related material data of predecessors, the author extracted the parameters σl0, Ck, γk, Q∞and b according to Chaboche combined theory on these three batches steel and built the relationship which lay the foundation for refined steel constitutive relation under reciprocating load between monotonic loading material and Chaboche parameters.Secondly, in combination with cruciform diaphragm welded joint hysteretic behavior tests, heat-affected zone thickness value, full penetration weld model and joint region meshing way were determined. Then the simulated verification was carried on the tests to make sure the numerical simulation method which was going to be applied on joint parameter analysis feasible.Lastly, considering diameter ratio of brace diameter and chord diameter β, chord thinness ratio γ, wall thickness ratio r, brace angle with chord θ, axial compression ratio u and gusset thickness a, parameter analysis on hysteretic behavior of cruciform diaphragm welded joint models were carried out. According to the analysis, the influence caused by the parameters changing on hysteresis curves, skeleton curves, ultimate bearing capacity, ductility coefficient, energy dissipation coefficient and the stiffness degradation were determined. And Menegotto-Pinto model was used to describe M-θ hysteretic skeleton curves of cruciform diaphragm welded joint, which was proved well-behaved with simulation resules.