钢次梁插入混凝土框架梁试验研究与力学分析(下)

Experimental study and analysis on specimens of steel secondary beam inserted in reinforced concrete girder of frame structure

进行了2个钢次梁锚入混凝土框架梁(4种不同形式节点)和1个悬挑钢次梁锚入混凝土框架梁静载试验,结果表明,钢梁端部的弯矩与剪力引起混凝土梁顶面受弯裂缝、侧面剪、扭斜裂缝,导致钢梁上部区域拔出引起节点锚固失效破坏;由于缺乏楼板及其配筋的约束作用和钢次梁悬链线效应的有利影响,悬臂钢梁承载力小于普通试件;600 mm高框架梁试件的钢梁端部嵌固能力比900 mm高框架梁试件小。论文提出节点应变分布模型,水平与竖直方向的内力分开考虑分析节点内力;研究了不考虑水平力的节点承压破坏的弯剪相关性,表明无量纲弯矩和剪力呈线性关系;分析了弯矩、剪力变化与板中钢筋达屈服、框架梁边缘混凝土压坏的应力状态关系,给出了有实用价值的内力计算公式及设计方法。

Test of two specimens(four different joints) of steel secondary beam embedded in reinforced concrete girder in frame structure and one specimen with steel cantilever beam embedded in reinforced concrete girder under static load were conducted.The steel beam up-region was pulled out because of the concrete cracks caused by the moment,shear and torsion at the upper zone of the concrete beam near the steel beam end,and embedded capacity of joints failed.Lacking restraint of concrete and the reinforcement of steel bar in the concrete slab and catenary action of restraint steel beam,the capacity of steel cantilever beam is much smaller than other beams.The restrain action of specimen-600 is smaller than specimen-900.Models for internal force analysis and strain distribution of joints are analyzed.The horizontal internal force and vertical force are considered separately during calculation and analysis process.The research on bending-shearing correlation of joints is studied while the horizontal force isn't taken into account.Results show that the non-dimensional moment varies linearly with the non-dimensional shear force.By investigating the moment and shear force variation,the stress state of the bar in the slab and the boundary concrete under the steel secondary beam is identified.In the end,practical design formula and method is proposed.