Study on the brace axial force-local deformation behavior of unstiffened CHS X-joints
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O R I G I NA L
Bida Zhao · JieyuZheng · ChengqingLiu SarvarSaydirakhmono · Qi Jiang · Ke Li
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Study on the brace axial force-local deformation behavior of unstiffened CHS X-joints
Received: 14 March 2020 / Accepted: 24 August 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Numerical parametric analysis is carried out to study the force-local deformation (F −δ) behavior of circular hollow section X-joints under brace axial force (including compression and tension) and chord stress. An exponential model is proposed to describe the F − δ curves of the X-joints. Parameters of the proposed model including two intercept forces and three joints stiffness (initial stiffness and two tangent stiffness) are determined by theoretical analysis, finite element (FE) analysis and nonlinear regression. The results show that the F − δ behavior under brace compression is significantly different from that of brace tension. Chord stress has little effect on the initial stiffness, but has a relatively large effect on the intercept forces and the tangent stiffness. The proposed model well predicts F − δ behavior of the X-joints from FE results, which including strength degradation caused by chord wall buckling. Keywords CHS X-joints · Axial force-local deformation behavior · Intercept force · Joint stiffness · Exponential model 1 Introduction Unstiffened tubular joints (the brace members directly welded to the surface of a chord) have been widely used in engineering structures due to simple fabrication, cost-effective and architecturally aesthetic. For unstiffened tubular joints, internal forces from the braces have to be transferred through the bending of the chord wall, which results in significant local deformation of some joints with a relatively thin-walled chord. Moreover, it is found that this local flexibility has a significant effect on the stability of whole structure and redistribution of member internal forces. Han et al. [1] were investigated the effect of joint stiffness on the stability capacities of K6 and K8 single-layer spherical latticed domes. The results shows that the stability capacity of the K6 (or K8) latticed dome with semirigid joints was decreased 30% (or 35%) from the corresponding latticed dome with ideal rigid joints due to the severe degradation of joint stiffness in the plastic phase. Ma et al. [2] performed experimental and finite element (FE) studies on a single-layer cylindrical reticulated shell and found that the B. Zhao · J. Zheng · Q. Jiang · K. Li College of Civil Engineering, Zhejiang University of Technology, Hangzhou 310023, China B. Zhao · C. Liu (B) · S. Saydirakhmono School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, China E-mail: [email protected] C. Liu Key Laboratory of High-speed Railway Engineering of Ministry of Education, Chengdu 610031, China S. Saydirakhmono Department of Civil Engineering and Architecture, Turin Polytechnic, University in Tashkent, Tashkent, Uzbekistan
B. Zhao et al.
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