A STUDY ON ASEISMIC PROPERTIES OF MOMENT-RESISTANT FRAMES WITH CONCRETE-FILLED TUBULAR BRACINGS

本研究的目的是：（1）明确钢管混凝土支撑节点的合理构造;（2）探讨钢管混凝土支撑抗弯框架抗震性能的评估方法。1996年，对平节点、十字形节点和翼缘节点模型进行了单调受压和拉伸试验。试验参数为节点板的插入长度和钢管的径厚比。试验结果表明，只要楔形长度大于空心管节点的规定值，每种节点的节点效率均可达到85%。钢管混凝土支撑的变形能力也可以通过各种类型的节点来实现。1996年和1997年，对钢管混凝土支撑进行了低周反复荷载试验。在试验中，在管子中观察到裂纹或断裂失效，而在接头中没有观察到 ...更多信息 S.因此，可以说，每种类型的节点都承受循环轴向荷载。此外，作者提出的估算方法还能准确地预测出管材发生裂纹或断裂的载荷循环次数。1997年，对钢管混凝土支撑D/T比分别为20（A框架）和30（B框架）的两个抗弯门式刚架进行了水平低周反复荷载试验。框架A试样表现出反对称的塑性崩溃机制之一。在该机构中，一对支撑中的一个弯曲，但另一个从未弯曲。框架B试件形成了两个支撑屈曲的对称机制。对称的机制可能是优选的，因为能量耗散可以预期的两个支撑。反对称机制是一个独特的现象，在框架与钢管混凝土支撑，但从来没有在框架与空心管状支撑。在耗能方面，钢管混凝土支撑框架可能比空心钢管支撑框架更有利，因为一对支撑中至少有一个支撑会起到耗能作用。少

The objectives of this study are (1)to make clear the proper details of joints for concrete-filled tubular bracings (CFT bracings) ; and (2) to discuss about an estimation method of the aseismic properties of moment-resistant frames with the CFT bracings. In l996, monotonous compression and tension tests have been conducted for the models of fiat gusset plate joints, cross-shaped gusset plate joints, and flange joints. The experimental parameters are the wadged lengths of the gusset plates and the diameter-to-thickness ratios (D/T ratios) of tubes. The test resulted that every type of the joint could have the joint effciency of 85%, if the wedged length would be larger than the specified values for the joints ofhollow tubular members. The deformability of the CFT bracings could be also realized by every type of joints. In l996 and l997, a cyclic loading test has been conducted for the CFT bracings. In the test, the cracks or breaking failures were observed in tubes but not in the joint … More s. Therefore, it can be said that every type of joints stands the cyclic axial loading. Adding to that, the loading cycles at which the crack or breaking happened in tubes could be accurately predicted by the Authors, estimation method. In l997, a horizontal cyclic loading test has been performed for the two moment-resistant portal frames with CFT bracings which tubes' D/T ratios were 20 (frame A) or 30 (frame B). The frame A specimen showed an anti-symmetrical one of the plastic collapse mechanisms. In the mechanism, one of a pair of bracings buckled but the other never buckled. The frame B specimen formed a symmetrical mechanism in which both of the bracings buckled. The symmetrical mechanism may be preferable because the energy dissipation could be expected for both the bracings. The anti-symmetrical mechanism is an unique phenomenon in a frame with CFT bracings but never in a frame with hollow tubular bracings. In terms of the energy dissipation, a frame with CFT bracings may be more advantageous than that with hollow tubular bracings, because one of a pair of bracings would contribute the energy dissipation at least. Less