Abstract

Nonlinear material models are needed for the capacity analysis of structural components. Often, 1D-beam element-based models are preferred over more sophisticated solid element-based modeling approaches due to their efficiency. However, their reliance on uniaxial material representations often overlooks the crucial influence of shear stresses, potentially leading to inaccuracies in predicting structural responses. In response, this study introduces a novel approach by integrating a multi-axial 3D concrete model within a 1D finite element framework, effectively capturing the effects of shear stresses. The proposed multi-axial elasto-plastic concrete model offers a comprehensive representation of concrete behavior under both tension and compression, thus enhancing the predictive capabilities of the analysis. By adopting a 1D beam-type finite element formulation, the research enables a detailed examination of shear wall behavior under lateral loading conditions. The main purpose of the thesis is to validate the developed finite element analysis tool which employs a sophisticated 3D concrete material model. The inelastic material behaviour of steel reinforcements bars has also been considered in the analysis. For the beam-type finite element, a 2-node formulation was adopted based on the Timoshenko theory so that the shear deformation effects are also considered in the analysis. For the modelling of the concrete bulk with 3D material model, the 8-node solid element with 6-degreesof-freedom per node including the nodal rotations was adopted. The numerical formulation is then used for pushover analysis of beams and shear walls and compared with experimental results from literature for validation purposes. Five different structural components are tested. Validation efforts include comparisons with experimental data from existing literature and alternative modelling approaches. Parametric studies are conducted by changing the span sizes of the structural components.