ABSTRACT

fib Model Code 2010 introduced for the first time a comprehensive system for the treatment of safety and uncertainty for structural assessment and design based by nonlinear analysis. The paper analyzes a selected example from the literature with shear failure when two different failure modes are observed depending on the choice of material parameters. This issue is critical for the global assessment by nonlinear analysis since it often involves assumptions about the statistical distribution of structural strength. When different failure modes are involved, i.e. by steel yielding or concrete failure, these assumptions may not be valid and the calculated design strength may not be on the safe side. The influence of different failure modes on the structural strength is evaluated mainly for the ECOV method, where the assumption of log-normal distribution is used. The global assessment by nonlinear analysis is compared with the analytical solutions based on standard Eurocode and Model Code 2010 shear formulas. The results show that even though the ECOV methods provides higher design strength values, the difference is not significant especially if one takes into account the overall uncertainties involved in reinforced concrete analysis and design.