Assessing the structural behavior of shear-critical prestressed concrete beams using Finite Element analysis and digital image correlation

The reported study firstly presents the results of an extensive experimental program consisting of 9 full-scale I-shaped prestressed concrete beams. Each specimen is subjected to a four-point bending test with monotonically increasing load until failure occurs. The investigated parameters are the amount of prestressing, the amount of longitudinal and shear reinforcement and the shear span-to-effective depth ratio respectively. Continuous full-field three-dimensional displacements were measured using two stereo-vision digital image correlation systems in both zones where a shear force occurs. In addition to the DIC systems, discrete displacements were measured using linear variable differential transformers. The experimental results are compared to analytical calculations according to Eurocode 2 (EC2) (CEN 2004). A severe underestimation of the experimentally observed shear capacity was found. In order to further investigate the discrepancy between experimental results and analytical calculations according to EC2, a parametric nonlinear Finite Element (FE) model was constructed using the general purpose FE software package ANSYS (v14) (ANSYS Inc. 2011). The ability of the FE model to reconstruct the experimental behavior is firstly validated by comparing the experimental to the numerical results concerning failure load, failure mode, (full-field) displacement data and cracking patterns at failure. Based on the numerical results, an investigation is performed of the shear-carrying mechanisms of the reported test specimens.