On the value of a reliability‐based nonlinear finite element analysis approach in the assessment of concrete structures

Abstract

The objective of this paper is to explore the value of reliability‐based nonlinear finite element analysis (NLFEA) over the currently available, standardized assessment methods. To our knowledge, no studies are available on this subject, and this paper provides a first insight into the value and reliability level of these assessment methods. The exploration is illustrated through three reinforced concrete structural members: a continuous girder, a continuous deep beam, and a high‐strength deep beam. The analysis is performed gradually: step by step advancing the approximation level of the mechanical and the probabilistic models. The added value of the reliability‐based NLFEA over the semi‐probabilistic Eurocode (EC) method is found to be on average 0.60. In other words: even if according to the semi‐probabilistic EC method the design action (Ed) is 60% higher than the design resistance (Rd), the compliance with the target reliability criterion can be demonstrated by a reliability‐based NLFEA. Furthermore, it is observed that the gain and its cause (i.e., more advanced mechanical or probabilistic models) are different for the three cases. Though this outcome is restricted to the analyzed cases and should be interpreted as an upper limit added value, it indicates that a more detailed physical representation of the problem and an explicit treatment of uncertainties may uncover substantial reserves compared with the currently available, standardized assessment methods. Hence, the reliability‐based NLFEA method offers a promising alternative in the assessment of existing structures, enabling to avoid expensive measures that might be needed based on simplified methods.

Comparison of advanced semi‐probabilistic methods for design and assessment of concrete structures

“…While this approach performs well and is fully justified for linear computational models, its use for nonlinear models is questionable and can lead to an overconservative design resistance 2,3 or may even fail. 4 In contrast, it is well known that the probabilistic analysis in combination with a non-linear finite element analysis offers a significant added value over the standard linear analysis and semi-probabilistic approach implemented in Eurocodes, 5 and researchers are highly motivated to develop novel techniques coupling the accuracy of the non-linear finite element analysis (NLFEA) with a realistic description of the basic variables by probabilistic modeling.…”

Assessment of posttensioned concrete beams from the 1940s: Large‐scale load testing, numerical analysis and Bayesian assessment of prestressing losses

“…A first possible solution lies in the use of adjusted partial factors as suggested by Caspeele et al 2 and applied by Gino et al 3 . Another solution is the application of more refined models such as the use of finite element models of the structure 4 . Nevertheless, appropriate input must be given to these models, among others regarding the material properties.…”

Reliability assessment of the behavior of reinforced and/or prestressed concrete beams sections in shear failure

“…Some applications of reliability analysis for reinforced concrete structures have been reported by (Schlune et al [32], Allaix et al [33], El Ghoulbzouri et al [34]; Olmati et al [35]; Słowik et al [36]), and prestressed concrete structures by (Rakoczy and Nowak [37], Hadidi et al [38]). The combination of nonlinear analysis with reliability methods for the assessment of the reliability index has been used (Robuschi et al [39], Slobbe et al [40], Grubišić et al [41]). This paper aims to develop numerical models making it possible to represent as faithfully as possible the physical phenomena studied, and that by the use of an efficient theoretical model for the analysis of the sections behavior in the shear loading in the case of the reinforced and/or prestressed concrete beams.…”