Punching shear in concrete reinforced flat slabs with steel fibers and shear reinforcement

Abstract Steel fibers in reinforced concrete increase the performance of slab-column connection once they increase ductility and energy absorption capacity of the concrete. The use of fibers in flat slabs may increase strength and change the mode of failure. The objective of this work is to present an experimental evaluation of punching shear strength of reinforced concrete flat slab with steel fibers and punching shear reinforcement. Eight square slabs, size 1800 mm by 1800 mm by 130mm, were loaded until failure by punching shear around the column. The models were divided in two groups, depending on the type of the concrete used (with or without steel fibers). The steel fiber volume used in the slabs of second group was of 0.9%. Each group was composed of four slabs: one without shear reinforcement and three with shear reinforcement (studs) distributed radially around the column. The use of steel fibers increased the ultimate strength of all flat slabs. In one of the slabs, the association of steel fibers with shear reinforcement changed the failure surface from outside to inside the punching shear reinforcement region.

摘要 钢纤维掺入钢筋混凝土后，可提升混凝土的延性与吸能能力，进而改善板柱节点的力学性能。在平板式楼板中掺入纤维，可提升结构强度并改变其破坏模式。本研究的目标为针对掺加钢纤维与冲切剪切（punching shear）配筋的钢筋混凝土平板楼板，开展冲切剪切强度的试验评估。共制备8块尺寸为1800mm×1800mm×130mm的方形楼板试件，通过柱周边冲切剪切荷载加载至试件破坏。根据混凝土是否掺加钢纤维，将试件分为两组，其中第二组试件的钢纤维体积掺量为0.9%。每组包含4块楼板试件：1块未配置抗冲切配筋，其余3块配置沿柱周径向分布的栓钉式抗冲切配筋。掺入钢纤维可提升所有平板楼板试件的极限承载力，在其中一块试件中，钢纤维与抗冲切配筋的协同作用使破坏面从冲切配筋区域外侧转移至区域内侧。