A safety-based evaluation of strut-and-tie methods for shear design of RC deep beams in accordance with international concrete codes

Abstract

On the basis of strut-and-tie models (STMs) in accordance with international concrete codes such as ACI 318-14, AASHTO LRFD, CSA A23.3, Eurocode2 and fibMC 2010, a safety-based evaluation of shear design methods for RC deep beams was performed and is reported in this paper. The variability in load actions and member resistances consisting of uncertainty in material characteristics, fabrication tolerances and modeling uncertainties were taken into account as random variables. Using Rackwitch-Fiessler’s procedure with typical ranges for normal and high strength concrete and an extensive range of live-to-dead load ratios, the reliability or safety indices used to measure the safety level were investigated. It was found that the deep beams made from normal strength concrete and designed using STMs following the international concrete codes considered here provided a satisfactory safety level. Finally, for each of the STMs for design of deep beams, probability-based reduction factors are suggested to fulfill the target reliability index by greater than 3.5.

Keywords

• deep beam
• strut-and-tie model
• structural concrete
• reliability analysis
• structural safety