External diaphragm joint has been widely used in concrete-filled steel tubular (CFST) structure because of its large stiffness, good plasticity, and high bearing capacity. This paper studied new external diaphragm joints designed to connect concrete-filled double steel tubular (CFDST) columns and steel beams. Experiments were conducted to investigate the cyclic performance of nine joint specimens subject to cyclic horizontal load and fixed axial load at the top of the column. The variable parameters considered in the test were axial load of the CFDST column, width of external diaphragm, configuration of anchorage web and beam to column bending stiffness ratio. The load–displacement hysteresis behaviors were discussed. Failure mode of the joints was mainly dependent on beam to column bending stiffness ratio (k) and axial compression ratio (n), so the limit of these two factors should be considered to avoid the column failure in engineering design applications. The shear strain level in panel zone was high especially for weak-column joints. Results also showed that initial stiffness of external diaphragm joint significantly increased with the improvement of axial compression ratio, but the stiffness suffered a sharp degradation; the ductility and energy absorption ability improved with the width improvement of the external diaphragm; ribbed anchorage webs effectively improved initial stiffness and bearing capacity of external diaphragm joints.

中文翻译：

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CFDST柱与钢梁外部膜片节点的循环性能试验。

外部膜片节点由于其大的刚度，良好的可塑性和高的承载能力而被广泛用于钢管混凝土（CFST）结构中。本文研究了设计用于连接混凝土双钢管柱（CFDST）和钢梁的新型外部隔膜节点。进行了实验，以研究九个关节试样在圆柱顶部承受循环水平荷载和固定轴向荷载的循环性能。在测试中考虑的可变参数是CFDST柱的轴向载荷，外部隔板的宽度，锚固腹板的配置以及梁与柱的弯曲刚度比。讨论了载荷-位移滞后行为。接头的失效模式主要取决于梁与柱的弯曲刚度比（k）和轴向压缩比（n），因此应考虑这两个因素的限制，以免在工程设计应用中发生柱破坏。面板区域的剪切应变水平很高，尤其是对于弱柱节点。结果还表明，随着轴向压缩比的提高，外膜节的初始刚度明显增加，但刚度急剧下降。随着外部隔膜宽度的增加，延展性和能量吸收能力得到改善；带肋的锚固腹板有效地改善了外部膜片节点的初始刚度和承载能力。