Collapse Load Estimation of Rectangular Reinforced Concrete Beam-Slab Systems-New Insights

摘要

This paper revisits the design o f simple rectangular reinforcedconcrete (RC) slabs, integrally connected to edge beams, supportedat the four corners, and subject to gravity loads. Typically, the edgebeams are made adequately stiff, whereby the slab can be analyzedand designed separately fo r two-way bending, considering theedges to be simply supported. This paper establishes, throughyield line analysis and experimental studies, that the final failure ismore likely to occur by a combined beam-slab failure—typically byone-way bending along the long-span direction, with plastic hingesforming in the middle o f the long-span beams. The conventionalyield line pattern (two-way slab-alone failure) m il occur only inexceptional cases where the long-span beams are heavily reinforced.It is clearly demonstrated that the actual mode o f failureand the collapse load are governed primarily by the relative beamslabstrength in all cases, regardless o f whether the edge beams arestiff or shallow. The proposed yield theory has also been validatedby experiments on square beam-slab systems reported in the literature.These new insights on collapse load estimation o f rectangularbeam-slab systems can lead to more rational and economicstrength design and detailing.