Advances in safety formats for non-linear finite elements analysis of reinforced concrete structures

The semi-probabilistic and probabilistic safety formats for the non-linear finite elements analysis (NLFEA) of reinforced concrete (RC) structures are of practical interest for structural designers. In order to estimate the design structural resistance, different methodologies based on global structural response have been defined in the literature and by the Codes (i.e., fib Model Code 2010 and EN 1992- 2). However, guidelines for the correct use of these safety formats for the evaluation of the structural safety through NLFEAs are still not present, in particular, when the structures may collapse with different failure modes. The present work compares the outcomes of different safety formats for the estimation of the design strength of five RC beams with and without web openings. The results of the experimental tests performed up to failure on the five beams are known from the literature. The applicability of the safety formats to the results of plane stress NLFEAs is discussed in function of the material properties adopted for the simulations (i.e., mean, characteristic and design values) and of the predicted failure mode. Based on the results, a new simplified safety format based on mean values of material properties is proposed. In conclusion, the useful recommendations related to the general applicability of the safety formats for NLFEAs of RC structures are commented.