无梁楼盖柱头直截面摩擦剪切探讨

Discussion on straight section frictional shear of column cap of flat slab

通过对美国规范中无梁楼盖柱头直截面摩擦剪切计算公式和国内已有试验研究结果进行对比分析表明,我国规范中无明确的直截面摩擦剪切验算公式及相关要求,对于某些极端情况下无梁楼盖的设计存在一定安全隐患,提出了进行直截面摩擦剪切承载力验算的建议公式。直截面摩擦剪切承载力与钢筋类别、混凝土强度等级、摩擦抗剪钢筋的配筋率、柱截面边长以及无梁楼盖板的箍筋配置情况和板厚有关,不能确定一个定值的参数用于控制是否验算直截面摩擦剪切承载力,提出了均应进行直截面摩擦剪切验算的建议。并提出了对于荷载较大、采用配置箍筋或弯起钢筋提高冲切承载力时,应特别重视直截面摩擦剪切验算;设计采用厚板时,即h0/bc超过1.0时应特别重视直截面摩擦剪切验算的建议,为工程建设标准编制和工程设计人员设计提供参考。

Based on the comparative analysis of the calculation formula of straight section frictional shear of flat slab in the American code and the existing experimental research results in China, it is shown that there is no explicit straight section frictional shear check formula and relevant requirements in the Chinese code, and there are certain safety hidden dangers in the design of the flat slab under some extreme conditions, and the proposed formula of straight section frictional shear bearing capacity check is put forward. Straight section friction shear bearing capacity and reinforced category, concrete strength grade, friction reinforcement ratio of shear reinforcement, column section length and the flat slab floor plate stirrup configuration and thickness, cannot determine whether a fixed value of the parameter is used to control the checking straight face friction shear bearing capacity, put forward to straight section friction shear calculation shall be recommended. It is suggested that when the load is large and the reinforcement stirrup or bent steel bar is used to improve the punching shear bearing capacity, special attention should be paid to the friction shear calculation of the straight section;when the thick plate is used in the design, that is, when h0/bc exceeds 1.0, special attention should be paid to the friction shear calculation of the straight section, which provides reference for the preparation of engineering construction standards and the design of engineering designers.