新型密肋叠合空心楼板抗冲切性能试验研究

Experimental Study on Punching Shear Performance of a New Type of Composite Multi-Ribbed Hollow Floor

现浇混凝土空心楼板具有结构跨度大、自重轻、综合造价低等优势。为适应建筑工业化发展趋势,本文提出三种构造形式密肋叠合空心楼板,实现现浇混凝土空心楼板的预制装配化。为研究新型密肋叠合空心楼板冲切性能,设计并制作5个密肋叠合空心楼板试件,对比双向矩形箍筋、单向矩形箍筋和单向钢筋桁架筋三种配箍方式对密肋叠合空心楼板冲切性能的影响。结果表明:密肋叠合空心楼板试件破坏模式均为冲切破坏,单向矩形箍筋试件相较于双向矩形箍筋试件其抗冲切承载力平均降低11.8%,单向钢筋桁架配筋试件相较于双向矩形箍筋试件其抗冲切承载力分别平均降低44.1%和60.8%;结合关键点位荷载-挠度曲线对比发现,单向钢筋桁架配筋试件相较于双向矩形箍筋试件冲切破坏后其残余承载力下降比例大13.7%,表明单向钢筋桁架密肋空心预制楼板抗冲切性能相较于双向矩形箍筋形式较弱,需对桁架钢筋加强以保证承载力和延性发挥。

The cast-in-place concrete hollow floor has the advantages of large structural span, light self-weight and low comprehensive cost. In order to adapt to the development trend of building industrialization, this paper proposes three structural forms of composite multi-ribbed hollow floors to realize the prefabricated assembly of cast-in-place concrete hollow floors. Five multi-ribbed hollow floor specimens are designed and fabricated for studying the punching shear performance of a new type of composite multi-ribbed hollow floor, and the effects of bidirectional rectangular stirrup, unidirectional rectangular stirrup and unidirectional steel truss reinforcement on the punching shear performance of the composite multi-ribbed hollow floor were compared. The results show that the failure modes of the specimens of multi-ribbed hollow floor are punching failure. The punching shear capacity of the specimens with unidirectional rectangular stirrup is reduced by 11.8% on average compared with that of the specimens with bidirectional rectangular stirrup. The punching shear capacity of the specimens with unidirectional steel truss is reduced by 44.1% and 60.8% respectively compared with that of the specimens with bidirectional rectangular stirrup. Combined with the comparison of the load-deflection curves at the key points, it is found that the decline ratio of residual bearing capacity after being punched and destroyed of the specimens with unidirectional steel truss is 13.7% larger than that of the specimens with bidirectional rectangular stirrup. It indicates that the punching shear resistance performance of multi-ribbed hollow precast slab with unidirectional reinforcement truss is weaker than that with bidirectional rectangular stirrup, and it is necessary to strengthen the truss reinforcement to ensure the bearing capacity and ductility.