Experiment on cold-formed steel quadruple-limb built-up box section columns under axial compression(PDF)
长安大学学报（自然科学版）[ISSN:1006-6977/CN:61-1281/TN]
- Issue:
- 2017年03期
- Page:
- 72-81
- Research Field:
- 桥梁与隧道工程
- Publishing date:
Info
- Title:
- Experiment on cold-formed steel quadruple-limb built-up box section columns under axial compression
- Author(s):
- NIE Shao-feng; ZHOU Tian-hua; ZHOU Xu-hong; HUO Yang-yang; SUN Yu-jin
- 1. School of Civil Engineering, Chang’an University, Xi’an 710061, Shaanxi, China; 2. School of Civil Engineering, Chongqing University, Chongqing 400044, China
- Keywords:
- structural engineering; cold-formed steel built-up box section column; axial compression performance; experimental study; failure mode; simulation analysis
- PACS:
- TU392.5
- DOI:
- -
- Abstract:
- To understand the mechanical properties of cold-formed steel built-up box section columns, the mechanical behaviors of 21 specimens of cold-formed steel single C-shaped, U-shaped and quadruple-limb built-up box section columns with different slenderness ratios were tested under axial compression load. The ultimate capacity and load-displacement curves of specimens were obtained. The flexural mode and failure characteristics were described in detail. The ultimate capacities of built-up specimens were calculated and comparatively analyzed by “effective ratio of width to thickness” in “Technical code of cold-formed thin-wall steel structures” (GB 50018—2002), “effective width method” and “direct strength method (DSM)” in “North American specification for the design of cold-formed steel structural members” (AISI S100—2007) and “simple superposition method”. Finite element models considering materials, geometric and contact nonlinearities were established by finite software ABAQUS to simulate and analyze the mechanical behaviors of the test specimens under axial compression. Furthermore, failure characteristics and load-axial displacement curves obtained by numerical analysis were comparatively analyzed with the experimental results so as to verify the validity of finite element methods. Influencing factors on behaviors of columns under axial compression, including slenderness ratio, spacing of screws and height-thickness ratio of web were analyzed through the proved FEM. The results show that the failure mode of middle and long single columns is local buckling and overall flexural buckling instability, while the failure mode of short single columns is local buckling and distortional buckling. Ultimate failure mode of middle and long built-up columns is overall flexural buckling around the weak axis, while that of the short columns is local plastic cripple. The ultimate bearing capacity and stiffness of built-up columns gradually decrease with the increase of slenderness ratio. For columns whose slenderness ratio is greater than 30, the built-up effect is obvious, therefore the screw connections can meet the requirements of making basic members work together cooperatively. For columns whose slenderness ratio is smaller, the built-up effect is weak, so it is non-conservative to calculate capacity by simple superposition method. The ultimate axial bearing capacity and stiffness of built-up box section specimens significantly increase with the decrease of height-thickness ratio of web.
Last Update: 2017-06-06