Utilization of Nonlinear Finite Elements for the Design and Assessment of Large Concrete Structures. I: Calibration and Validation

Abstract

This two-part paper is an application of advanced nonlinear finite-element analyses (ANFEA) for the design or assessment of large concrete structures. It presents an innovative application of ANFEA that reveals many important aspects of numerical modeling and safety verification, starting from the material up to the structural level and going from calibration and validation to the prediction level. A complex hydraulic structure with large members and nonconventional boundary conditions is taken as the target design structure (TDS). Following a two-step procedure that was proposed in a previous paper, the model error is first computed for two candidate concrete models (part 1). Using the selected concrete model and the corresponding model error, the global resistance factor is computed in a second step for the TDS (part 2). This first part is related to the calibration and validation assessments for the ANFEA models of concrete structures. These issues can be viewed as two basic steps within the verification and validation process (V&V) that has been adopted in other engineering fields. In the calibration procedure, the size effect phenomenon, which is a major parameter for the TDS, is considered. The distinction between size effect statistical (material) and deterministic (energetic) components is highlighted, and a new approach for considering each contribution is presented. The validation process is undertaken from the material to the structural level. It is shown through this process that the use of only the compressive strength of concrete and the yield stress of reinforcement are sufficient with one candidate concrete model in order to obtain a relatively low coefficient of variation of model error. The paper illustrates a general methodology that can be applied with any ANFEA software to design or assess the safety level of unusual concrete structures.