预应力混凝土扁梁框架节点抗震性能试验研究

Experimental study on seismic behavior of prestressed concrete flat beam frame joints

通过4个预应力混凝土宽扁梁框架边节点在低周反复荷载作用下的抗震试验研究,对宽扁梁边节点在模拟地震作用下的破坏形态、特征荷载、滞回特性、骨架曲线、延性以及耗能能力等抗震性能进行分析研究。研究表明：试件初裂出现在靠近柱附近的梁,最终破坏区域发生在节点外核心区剪切破坏;荷载位移滞回曲线基本上呈梭形且相对饱满,试件位移延性系数介于3.7~5.13,具有较好的延性及耗能能力;穿过节点外核心区的预应力筋数量变化时,试件的延性及耗能能力变化不明显;试验中出现外核心区内的扁梁纵筋与混凝土黏结滑移破坏,混凝土剥落,而内核心区水平箍筋并未达到极限强度,建议在扁梁框架节点的设计应设置构造竖向垂直箍筋。总体上看,预应力混凝土宽扁梁框架边节点具有一定的抗震性能,可以通过合理的构造措施将其应用于抗震结构中。

The seismic behavior of four prestressed concrete flat beam frame exterior joints are studied under low frequency reversed loading. The failure features,characteristic loads,hysteresis loops,skeleton curves,ductility and energy dissipation of exterior joints are analyzed under seismic loads. Studies show that the first crack appears in the vicinity of beam-column,and the final failure occurs mainly in the joint outer region. The load-displacement hysteresis loops of joints are plump,and the displacement ductility coefficient is between 3. 7 and 5. 13,which reflect that joints have good ductility and energy dissipation capacity. The change of ductility and energy dissipation capacity is not obvious with the number of prestressing tendons through the outer joint core area. The failure pattern of specimens is bond slip mechanism of the interface between rebars and concrete in the joint outer region,while the joint inner core area does not reach the ultimate strength of stirrups. It is recommended flat beam frame joints should be set vertical stirrups in the joint outer region. We can conclude that prestressed concrete flat beam-column joints have good seismic perfomance,and can be applied to the seismic structure by reasonable construction measures.