梁腹板开圆孔钢框架梁柱节点的性能研究

INVESTIGATION ON BEHAVIORS OF THE CONNECTION WITH OPENING IN BEAM WEB OF STEEL MOMENT RESISTING FRAMES

梁腹板开圆孔节点是根据地震作用下钢框架梁柱节点可能产生脆性破坏的现象而提出的一种新型削弱型节点,该节点兼备提高建筑净空的优点,并不增加施工难度。在梁腹板上开设孔洞,不会影响梁的整体稳定性,只会影响梁的局部稳定性,并且由于梁翼缘参与抗剪比重增大,其抗剪承载力也不会发生较大幅度的下降。对梁腹板开圆孔节点进行的有限元分析表明:在适当位置开设一定大小的圆孔,可以首先在梁削弱截面处会形成空腹梁机制(Vierendeel mechanism),迫使塑性铰出现在梁上削弱部位,远离梁根部节点焊缝区,并且节点承载力不发生显著下降。节点实验的结果与有限元分析相吻合,即梁柱连接焊缝的脆性断裂是传统节点的主要破坏形式,而削弱处形成的空腹梁机制是导致梁腹板开圆孔节点破坏的原因,如果开孔合适,腹板开孔节点的各项性能指标下降幅度很小(5%以内),但可确保塑性铰产生在梁上。根据梁腹板开圆孔节点不同的受力状态可以将梁段划分为三种区间,即格构式梁段、过渡段和实腹式梁段,如果腹板所开圆孔合适,过渡段会先形成空腹梁机制,并满足预期的设计目标。

The opening in beam web （OBW） connection is a new kind of beam-to-column connection of steel moment resisting frames （MRFs）. Numerical studies show that the OBW connection may have good properties under cycling loading, for instance, pipeline may go through the beam directly if the weakened parameters R （opening size） and b （opening location） are in a proper scope so as to increase the function of the building. Web weakened only affects local buckling of beam around the opening. The shear resistant capacity of beam with web opening may not decrease due to the contribution of the shear resistant capacity of flange. Vierendeel mechanism will be formed in the weakened area, which leads to yielding of connection, and plastic hinge always stays around web opening without significant decreasing of yielding load. Results drawn from experiments are in accordance with those from numerical analysis, i.e., brittle weld fractures appeared in the conventional all-welded connection of steel MRFs that lead to failure of connection; but for the OBW connection, Vierendeel mechanism is formed in the weakened area that lead to plastic failure of connections. The OBW connection can be divided into three parts according to its behavior, and aseismic behavior of the OBW connection depend on the weakened parameters, R and b.