This paper presents an experimental investigation of the load-carrying capacities of stainless steel hybrid tubular X-, T- and Y-joints with square braces and circular chord under monotonic loading. In total, 18 tests are reported on hybrid tubular X-, T- and Y-joints, including 9 tests on X-joints, 4 tests on T-joints and the remaining 5 tests on Y-joints. All test specimens were made from austenitic stainless steel of grade AISI 304. The material properties of the test specimens were determined by tensile coupon tests. The failure modes, load-carrying capacities and axial load versus displacement and deformation curves were obtained for all test specimens. The influences of brace width-to-chord diameter ratio (β) on the failure modes and load-carrying capacities of tubular joints were considered. For the specimens with small β value, the chord face plastification was more likely to occur and there was no obvious peak load observed in the load-displacement and load-deformation curves. For the specimens with large β value, the chord side wall failure was dominant. The clear peak load was observed in the load-displacement and load-deformation curves. The test strengths are compared with the results predicted by the current design rules in accordance with International Committee for the Development and Study of Tubular Structures (CIDECT) (2001), Eurocode 3 (EC3) (2005), Chinese Code (GB50017) (2017) and Australian/New Zealand Standard (AS/NZS) (2001). Upon comparison, it is found that the joint strengths calculated using AS/NZS (2001) are larger than test strengths by 2% on average. It is shown that the design formulae provided by CIDECT (2001), EC3 (2005) and GB50017 (2017) are conservative by around 6%, 19% and 20%, respectively, when compared to the test strengths.

本文提出了在单调加载下具有方括号和圆弦的不锈钢混合管状X，T和Y接头的承载能力的实验研究。总共报告了18个关于混合管状X，T和Y接头的测试，包括9个关于X接头的测试，4个关于T型接头的测试以及其余5个关于Y型接头的测试。所有试样均由AISI 304级奥氏体不锈钢制成。试样的材料性能通过拉伸试样试验确定。获得了所有试样的破坏模式，承载能力以及轴向载荷与位移和变形的关系曲线。支撑宽度与弦直径之比（β的影响）考虑了管状接头的破坏模式和承载能力。对于β值较小的标本，更可能发生弦面塑化，并且在荷载-位移和荷载-变形曲线中均未观察到明显的峰值荷载。对于具有大β的样本值，弦侧壁故障占主导。在载荷-位移和载荷-变形曲线中观察到清晰的峰值载荷。根据国际钢管结构开发和研究委员会（CIDECT）（2001），欧洲规范3（EC3）（2005），中文规范（GB50017）（2017），将测试强度与当前设计规则预测的结果进行比较）和澳大利亚/新西兰标准（AS / NZS）（2001）。通过比较，发现使用AS / NZS（2001）计算的接头强度平均比测试强度大2％。结果表明，与测试强度相比，CIDECT（2001），EC3（2005）和GB50017（2017）提供的设计公式分别保守了约6％，19％和20％。