超大承载力端板连接节点试验研究

Experimental study on ultra-large capacity end-plate connections

在大跨或重载钢结构中,当梁柱之间需要采用螺栓连接时,如果普通构造的端板连接节点和大承载力端板连接节点不能满足承载力要求,则需要采用受拉区布置12颗或16颗螺栓的超大承载力端板连接节点。为研究该类型节点受力性能,进行4个超大承载力端板连接节点足尺试件的单调加载试验,得到各节点试件的弯矩-转角曲线,分析不同螺栓直径、端板厚度和螺栓布置形式下各节点的抗弯承载力、转动刚度和受拉区螺栓拉应变增量分布的特点。结果表明,在试验试件构造条件下超大承载力端板连接节点的弯曲失效模式为端板屈服后螺栓失效,端板厚度对节点承载力影响明显;各螺栓的拉应变增量分布不均匀,角部螺栓对节点抗弯承载力影响较小,建议在设计中移除或仅按抗剪螺栓考虑;建议节点域屈服承载力仍按照现行规范计算,该类节点的等效受拉螺栓数量取为7。

When bolted connections are required in the structures with large spans or heavy loads, the ultra-large capacity end-plate connection with 12 bolts or 16 bolts arranged in the tension region should be applied if the ordinary end-plate connection or the large capacity end-plate connection cannot satisfy the capacity requirement. In order to study the behavior of ultra-large capacity end-plate connections, four full-scale specimens were tested under the monotonic loads. Based on the tests, the moment-rotation curves for all specimens were obtained, and the moment resistance, the rotational stiffness and the distribution of the tensile strain increment of bolt in the tension region were analyzed with different bolt diameters, different end-plate thickness and different layout of bolts. According to the results, the ultra- large capacity end-plate connections in the tests may fail in the mode that the bolts fail after the yielding of end plate, and the thickness of end plate may obviously affect the resistance of connections. Significant non-uniform distribution of the tensile strain increments in bolts was observed. Since they contribute little to the moment resistance of connections, it is recommended that the bolts at the corners should be removed or should be considered as shear resistant ones. In the design of this connection, the resistance of the panel zone still can be calculated according to the current code, and it is recommended that the equivalent number of the bolts in tension should be 7.