【摘要】 "强柱弱梁"和"强节点弱构件"是钢筋混凝土延性框架结构抗震设计中的重要概念。然而受楼板参与工作、双向地震动作用等因素的影响,抗震规范中规定的抗震构造措施可能无法保证上述抗震概念的实现。针对我国中低烈度区的既有多层钢筋混凝土框架结构,设计4个包含底层柱脚的空间梁柱节点试验体,其中包括2个中柱节点和2个边柱节点,并通过双向往复加载试验,考察空间双向加载作用和现浇楼板对其承载力、延性和破坏模式等方面抗震性能的影响。试验结果表明,无论是否考虑现浇楼板的作用,按抗震规范设计的三级框架节点试验体在双向往复荷载作用下均未出现预期的"强柱弱梁"的破坏模式。相反,2个中柱节点试验体均在底层柱脚发生脆性破坏,2个边柱节点试验体均在底层柱顶与节点区附近发生脆性破坏。特别是对于边柱节点,由于节点区在一侧缺少梁的约束而过早发生节点区破坏。其承载力明显低于中柱节点。在这种破坏模式下,楼板的存在对于构件承载力影响不大,但楼板为边柱节点区提供的约束作用有助于在一定程度上提高其非线性变形能力。更多还原

【Abstract】 ‘Strong column-weak beam’and ‘strong joint-weak member’are the important design principles for the ductile moment-resisting reinforced concrete( RC) frames. The desired seismic performance governed by these principles,however,may not be easily realized because of various uncertainties including the contributions from the castin-place RC slabs and the in-filled wall members as well as the bidirectional earthquake actions. Four 1: 2-scale threedimensional RC beam-column joint specimens,two for the interior joints and the other two for exterior mid-edge joints,are tested under the bidirectional cyclic loading for the impacts of bidirectional loading and the contribution of cast-inplace slabs on the seismic performance of RC frames including the bearing capacity,ductility and failure modes. The test results show that all specimens failed to exhibit the desired mechanism of ‘strong column-weak beam ’ under bidirectional cyclic loading regardless of the presence of slabs,although they are designed according to the Chinese seismic design code. Instead,the brittle failure of interior joint specimens may occur at the bottom end of the column,while for the failure of exterior joint,it may occur as the consequence of the reduced beam confinement in the joint zone and the lower strength. For such failure modes,the presence of slabs has little impact on the bearing capacity of the joint specimens,but the confinement of exterior joint zones provided by the slabs is beneficial to the increase of deformability of the joint.更多还原