Influence of Design Parameters on Tensile Membrane Action in Reinforced Concrete Slabs

Abstract

Reinforced concrete slabs are traditionally designed to carry a specified design load for adequate capacity at ultimate limit state (ULS). In case of an accidental event, however, tensile membrane action can be activated to establish an alternative load path, which will delay or prevent the collapse of the structure. As such, this tensile action increases the bearing capacity, safety and, hence, the robustness of structures. However, research on this important strength reserve is scarce and the residual capacity is commonly not taken into account during the design. In previous contributions of the authors, a unique test set-up was developed and described to investigate the tensile behaviour of slabs under large deformations because of the accidental removal of a support. A set of three real-scale reinforced concrete slabs of a total length of 14 m was tested. The experiments provided a unique set of data that was subsequently used to develop and validate a numerical model. In this study, this numerical model was used to perform a parameter study to identify the influence of the most important design parameters: span length, slab thickness and reinforcement (ultimate strain and geometric ratio); the results of the analysis are presented in this article. Further, the boundary conditions were shown to have an important influence on the development of tensile membrane action and this effect was investigated considering different restraint conditions as well as using the finite element model analysis of a frame.