Shen Ma, Ab van den Bos (DIANA FEA bv)

The Model Code 2010 was published with safety formats to extend the checks of reinforced concrete structures, re-examinated by nonlinear analysis. Model Code 2010 also gives approaches for the verification of structural safety in ULS (Ultimate limit state). There are three approaches: 1. Probabilistic method; 2. Global resistance methods; 3. Partial factor method. This paper focuses on global resistance methods, which includes GRF (Global Resistance Format) and ECOV (Estimation of Coefficient Of Variation) in a nonlinear analysis of a reinforced concrete structure. The example structure in the paper is a circular shape RC foundation, supported by piles. The foundation is fully simulated as a finite element model (concrete and reinforcement details) in a 3D environment. The paper contains the input parameter studies of the finite element model and the output results of the analysis, based on ECOV method and the latest guideline from Rijkswaterstaat (Dutch Ministry of Infrastructure and the Environment, RWS 2016). ECOV method requires two nonlinear analyses in order to determine the safety factor of ULS: The first analysis is executed with mean value material properties, and the second one is done with characteristic values. As a conclusion, the design of the foundation meets all the requirements in ULS by ECOV method. Model Code 2010 does not state any specifications for checking the structure in SLS when ECOV method is applied. As an extended study of ECOV method, this paper also gives a recommended method to check the safety of the structure in SLS. The “design-check” workflow, which is mentioned in this paper, could give clear guidance about the ECOV method for practical engineering design with (and without) FEA. There are also recommendations/remarks given in the end of this publication, which are related to ECOV method in Model Code 2010.

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