Analysis Of Ultimate Bearing Capacity And Hysteretic Performance For Overlapped Joints With Square Chords And Circular Braces

Overlapped K-joint is one of usual joints in the hollow steel section structures, so people attach importance to it. But now the design of this structure still has some flaws. The relationship between geometric parameter and ultimate bearing capacity is not obvious as various complicated geometric shape. The question whether hidden weld is welded or not is not mentioned in the current code for steel structures. Little information of overlapped K-joint with square chords and circular braces was available, which leads to restrict its applications to some extent. There is little study on hysteretic behavior of joints under cyclic axial loading.As joint is the critical connection part of structure, the research for its static and hysteretic performance has important realistic significance. This article has mainly carried on the following work. 1. By using ANSYS program, numerical simulation analysis of a series of K-jointswith square chords and circular braces under different lapped ratio is carried out so that the static behavior of the joint is investigated and explained graphically. The relationship between geometric parameter and ultimate bearing capacity is revealed. A comparison is made between overlapped joints and zero-gape joints.The results indicate that when wall thickness ratio of brace to chordτis small, lapped ratio Ov has less significance on the ultimate bearing capacity of K-joints and the ultimate bearing capacity of overlapped joints is lower than those of zero-gape joints. When ratioτis great, ultimate capacity increases with Ov grows and the ultimate bearing capacity of overlapped joints is higher than those of zero-gape joints.2. The analysis of relationship between hidden weld, loading hierarchy reversal of braces and ultimate bearing capacity is made. The results indicate that the absence of hidden welds has less significance on the ultimate capacity of the through-brace-in-compression joint than on that of through-brace-in-tension joint. Furthermore, the effect of loading hierarchy reversal of braces on overlapped joints should not be neglected.3. The analysis of relationship between geometric parameters and hysteretic behavior is made. It is proved that it is feasible to analyze the hysteretic behavior of joint under axial cyclic quasi-static loading.4. Based on the results, some overlapped K-joints under cyclic axial loading were analyzed, including hysteretic curve, skeleton curve, deformation capacity, energy dissipation, stiffness decay and so on. The results showed that overlapped K-joints with square chords and circular braces has good ductility and aseismic capacity.