Numerical Analysis of a Prestressed Non-reinforced Ultra-Thin Concrete Shell

Abstract

Concrete shells are very appealing structures. However, their use is nowadays residual due to higher construction costs, mostly related to the complex and non-reusable molds, including the falsework. This paper presents part of the research work conducted in the scope of the PRESHELL project which aims to produce concrete shells at low cost. In particular, a numerical study was conducted to investigate the effects of prestress on a non-reinforced ultra-thin concrete shell. Since the form of the shell corresponds to the anti-funicular of a membrane subjected to its self-weight, non-uniform loads tend to cause significant tensile stresses. To solve this situation, a layout of embedded strands was proposed, based on the directions of the principal stresses generated by the most critical load combination. To analyze the effects of the prestress, a numerical model of the non-reinforced concrete shell was built using the ABAQUS software. Results of the numerical analysis show that the effect of prestress, according to the proposed strands layout, can improve the load carrying capacity of the shell to non-uniform loads. Prestress can also reduce the magnitude of the tensile stresses, including their spatial extent. However, embedded cables and shell’s curvature produce undesirable and permanent tensile radial stresses. Therefore, an in the case of non-reinforced shells, the use of fiber reinforced materials is encouraged.