装配式钢管混凝土柱-混凝土叠合梁连接节点试验研究

在装配式钢管混凝土结构中，钢管混凝土柱与钢筋混凝土梁的连接方式较为复杂。首先设计一种钢管混凝土柱–混凝土梁连接节点，可以在工厂预制大部分构件，在现场进行装配，满足装配式施工要求。通过装配式施工制作5个梁柱节点试件，包括3个中间节点和2个端节点试件。对该5个节点试件进行试验研究，其中1个中间节点试件进行单调加载，考察节点的静力承载力与变形性能；其余4个试件进行低周反复加载，根据试验得出节点在低周反复荷载作用下的破坏特征及滞回曲线、延性系数、耗能能力和强度刚度退化规律等。结果表明：试件破坏位置均在叠合梁上，符合强柱弱梁及强节点弱构件的设计原则；叠合梁截面尺寸为200 mm×350 mm的试件滞回曲线较为饱满，没有明显的捏缩现象，延性系数介于3.77与6.60之间，平均等效黏滞阻尼系数为0.222，节点的抗震耗能能力较好；叠合梁截面尺寸为250 mm×450 mm的试件由于叠合梁中部箍筋没有加密，叠合梁发生了剪压破坏，节点耗能能力未得到充分发挥，可以通过加大箍筋加密区的长度提高节点的耗能能力；试件强度退化系数一般均大于0.9，表明强度和刚度退化比较稳定；所有节点试件的倒“T”形连接件钢板均没有屈服，其抗弯和抗剪承载力为钢筋混凝土梁1.3倍的设计，偏于安全。

Experimental Study on Prefabricated Concrete Filled Steel Tube Column and Composite Beam Connections

The connection between concrete-filled steel tube column and reinforced concrete beam in the prefabricated concrete filled steel tube structure has been a complicated issue.In this study,a new type of concrete filled steel tubular column and concrete beam connection was first designed to satisfy the requirement from the prefabricated construction process,enabling the prefabrication of most assembly parts and rapid assembling at the construction site.Five beam-column connection specimens,three intermediate connection and two end connection,were prefabricated.All the five specimens were tested in the laboratory;one of them was subjected to static and monotonic loading in order to check the bearing capacity and deformation capability of the connection,while the other four were tested under cyclic loading.The failure modes,hysteretic behavior,ductility,energy dissipations and degradations of strength and stiffness of the tested specimens were obtained.It was observed that the ultimate failure occurred at the composite beams,conforming to the basic design concept of strong column,weak beam and strong joint,weak member.The recorded hysteresis curves of the specimens with composite beam cross-section of 200 mm×350 mm were relatively plump without apparent knead shrinkage phenomenon,the ductility coefficient varied from 3.77 to 6.60,and the average equivalent viscous damping coefficient was 0.222,revealing favorable seismic energy dissipation capacity.For the specimens with composite beam cross-section of 250 mm×450 mm,the energy dissipation capacity of the connections were not fully developed due to the limited stirrup reinforcement,resulting in shear-compression failure.The length of the stirrup reinforcement district can be extended to enhance the energy dissipation capacity of the connection.Moreover,stable degradation process of strength and stiffness was also demonstrated since most of the strength degradation coefficients of specimens were found to be higher than 0.9.The yielding strength has not been exceeded for all the T-shaped plates in the tested connections,and the design of the T-shaped plate with bending and shear capacities being 1.3 times those of the connected concrete beam is confirmed to be reliable.