钢框架梁翼缘削弱型节点力学性能的试验研究

EXPERIMENTAL STUDY ON THE MECHANICAL PROPERTY OF REDUCED BEAM SECTION CONNECTIONS OF STEEL FRAMES

梁翼缘削弱的梁柱刚性连接是将塑性铰外移的一种典型节点形式。为研究这种连接形式在循环荷载作用下的滞回性能,共进行了6个模型的拟静力加载试验,其中5个模型用于研究梁翼缘的削弱深度、削弱长度、削弱起始位置对节点连接的破坏形态、极限荷载、最大塑性转角、延性性能的影响。作为比较,还进行了一个传统型梁柱全焊接刚性模型连接的试验。试验结果表明:梁翼缘削弱节点比传统梁柱刚性连接具有良好的塑性变形能力和耗能性能,试验中5个节点的塑性转角都大于0.04rad,延性系数大于4.0,达到了抗弯钢框架连接塑性转角不小于0.03rad,延性系数不小于4.0的要求。而普通梁柱全焊接刚性连接的塑性转角仅达到0.026rad,延性系数仅为2.4。5个试件的破坏主要以翼缘削弱处平面外刚度较弱而导致梁发生扭转失稳或梁下翼缘与柱连接的对接焊缝的脆性断裂为主。研究结果表明:将梁翼缘进行适当的削弱后形成的骨型节点可以增加梁柱节点的耗能性能,是一种较为理想的延性节点。

Reduced beam section （RBS） connection of steel frame is one of the typical forms to move plastic hinge outward from the beam and column interface. Six specimens under quasi static load were tested to investigate their hysteretic behaviors. Five of them were designed with different depths, lengths and distances from column surface to examine their effects on failure mode, ultimate load, plastic rotation angle and ductility. One specimen with full welded connection acted as a counterpart. The test results show that the five RBS specimens have better ductility and larger capacity of consuming energy than traditional connections. The plastic rotation angles of the five RBS specimens exceeded 0.04rad, with ductility coefficient greater than 4.0, meeting the requirement for plastic rotation angles of 0.03rad and ductility coefficient of 4.0. As a comparison, the plastic rotation angle of the traditional connection was only 0.026rad, and the ductility coefficient was only 2.4. The main failure patterns of the five RBS specimens were lateral-torsional bulking （LTB） and crack in weld near beam-flange. It shows that RBS connection is effective to enhance the capacity of consuming energy for steel frame.