Load-Carrying Capacities of Fully Clamped RC Slab Accompanying Compressive-Tensile Membrane Actions: A Theoretical Approach

Abstract

Fully clamped reinforced concrete (RC) slab is a common structural component possessing better load-carrying capacity over simply supported slab. Currently, typical yield line theory is a popular approach to estimate the bearing capacity of fully clamped RC slab, although it would greatly underestimate the actual ultimate resistance. This paper is devoted to enriching the knowledge of membrane action and its contribution to the load-carrying capacity of the clamped slab. The resistance trajectory of fully clamped RC slab from loading to failure undergoes three phases: the ascending branch raised by outward movement prevention, the descending branch due to crushed concrete and the re-ascending branch caused by reinforcement strain. Applied load–deflection curves of RC slab accompanying compressive-membrane actions are achieved according to the bending theory of normal cross-section. The reserve capacities accompanying tensile-membrane actions in the condition of large deformations are further derived. The whole load–deflection curves that considered compressive-tensile membrane effects are finally presented, where the mid-span displacements are revised by the deflection equations and the softening coefficient of flexural rigidity. It is indicated that the load–deflection relationships of fully clamped RC slabs can be reasonably depicted by taking compressive-tensile membrane effects into account, which are fairly different from yield line approaches. Comparative analysis shows that analytical results are in good agreement with experimental data reported by Park et al. and illustrates that the proposed model is capable of predicting the bearing capacity of fully clamped RC slab with very good accuracy.