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Abstract

Test results of 24 reinforced concrete dapped-end beams with shear span-to-depth ratios larger than unity are reported. The main variables studied were compressive strength of concrete, shear span-to-depth ratio, and main reinforcement and vertical stirrups of dapped-end beams. The test results indicate that the dapped-end beams all failed by flexure. The shear strength of dapped-end beams increases with increase in compressive strength of concrete. With smaller shear span-todepth ratio, the dapped-end beams show greater stiffness and ultimate load. The shear strength predicted by the proposed model, the strut-and-tie model of the ACI Code, and the approach of the PCI Design Handbook are compared with available test results. The proposed model can accurately predict the shear strength of dapped-ends in different failure patterns. More conservative predictions are obtained from the strut-and-tie model of the ACI Code while scattered predictions are obtained from the approach of the PCI Design Handbook. The proposed model can consistently predict the shear strength of dapped-ends at diagonal compression failure with different shear span-to-depth ratio, compressive strength of concrete and parameters of flexural tensile reinforcement. To ensure a ductile flexure failure, it is suggested that dappedend beams be designed using high-strength concrete and low ratios of flexural tensile reinforcement.

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