A test programme looking into the stress concentration factors (SCF) of cold-formed high strength steel (CFHSS) traditional (without brace and/or chord rotation) and member-rotated tubular T-joints is described in this paper. The brace members of traditional T-joints were made of square, rectangular and circular hollow sections (SHS, RHS and CHS), while the brace members of member-rotated T-joints were made of SHS and RHS. On the other hand, the chord members of traditional and member-rotated tubular T-joints were made of SHS. In this study, member-rotated T-joints, include brace-rotated (BR), square bird-beak (SBB) and diamond bird-beak (DBB) tubular T-joints. The tubular members were cold-formed from thermomechanical control processed (TMCP) S900 and S960 steel grades plates. A total of 12 tests was conducted in this experimental investigation. An axial compression load was applied through the brace member, while the chord ends were supported on rollers. The brace and chord members of tubular T-joints were connected using the robotic gas metal arc welding process. The values of normal brace width-to-chord width ratio ($\beta$) ranged from 0.33 to 0.73, effective brace width-to-chord width ratio ($\beta$’) ranged from 0.40 to 0.87, brace thickness-to-chord thickness ratio ($\tau$) ranged from 0.66 to 1.28 and chord width-to-chord thickness ratio (2$\gamma$) ranged from 20.6 to 39.0. The quadratic extrapolation method was used to estimate hot spot strains at the weld toes using the strains measured in the extrapolation regions. The experimental SCF values of CFHSS traditional and member-rotated tubular T-joints were compared with the SCF values obtained from the parametric equations given in the CIDECT (Zhao et al., 2001, [1]) and studies (Tong et al., 2013, [2]; Li et al., 2018, [3]; Tong et al., 2015, [4]). It was found that the existing SCF parametric equations given in the literature (Zhao et al., 2001, [1]; Tong et al., 2013, [2]; Li et al., 2018, [3]; Tong et al., 2015, [4]) could not accurately predict the SCF of cold-formed traditional and member-rotated tubular T-joints made of S900 and S960 steel grades.

本文描述了一个测试程序，研究冷弯高强度钢 (CFHSS) 传统（无支撑和/或弦杆旋转）和构件旋转管状 T 形接头的应力集中系数 (SCF)。传统T型接头的支撑杆采用方形、矩形和圆形空心型材（SHS、RHS和CHS）制成，而杆件旋转T型接头的支撑杆采用SHS和RHS制成。另一方面，传统的和构件旋转的管状 T 型接头的弦杆由 SHS 制成。在这项研究中，成员旋转 T 型接头包括支撑旋转 (BR)、方形鸟嘴 (SBB) 和菱形鸟嘴 (DBB) 管状 T 型接头。管状构件由热机械控制加工 (TMCP) S900 和 S960 钢级板冷成型。本次实验研究共进行了 12 次测试。轴向压缩载荷通过支撑构件施加，而弦杆端部由滚子支撑。管状 T 型接头的支撑和弦杆构件使用机器人气体保护金属电弧焊工艺连接。正常支撑宽弦宽比值（$\beta$) 范围从 0.33 到 0.73，有效支撑宽弦宽比 ($\beta$') 的范围为 0.40 到 0.87，支撑厚度与弦杆厚度比 ($\tau$) 范围从 0.66 到 1.28 和弦宽与弦厚比 (2$\gamma$) 的范围从 20.6 到 39.0。二次外推法用于使用外推区域中测量的应变来估计焊趾处的热点应变。CFHSS 传统和构件旋转管状 T 型接头的实验 SCF 值与从 CIDECT（Zhao 等人，2001，[1]）和研究（Tong 等人， 2013, [2]; Li et al., 2018, [3]; Tong et al., 2015, [4])。发现文献(Zhao et al., 2001, [1]; Tong et al., 2013, [2]; Li et al., 2018, [3]; Tong et al., 2018, [3]; Tong et al., 2013, [2]; ., 2015, [4]) 无法准确预测由 S900 和 S960 钢种制成的冷弯传统和构件旋转管 T 型接头的 SCF。