Numerical modelling of GFRP reinforced thin concrete slabs

With the development of new glass fiber reinforced polymer (GFRP) bars for RC structures, their application extends simultaneously. The non-corrosive nature of GFRP bars enables maximal lowering of the concrete cover, thus making them very suitable as a reinforcement in thin RC plate elements. Such thin members are usually prefabricated and used as façade panels, pavement or components of sandwich panels. Along with experimental studies, the finite element (FE) numerical modeling represents very useful tool for assessing and predicting the structural member behavior. Proper choice of material constitutive models and strategy of concrete/bar bond implementation always presents challenge when dealing with numerical FE modelling of RC structures. This study considers FE modelling of thin GFRP RC slabs’ flexural behavior under three-point bending test setup. It uses direct bond approach, that is, explicit simulation of the bond-slip effect between concrete and reinforcing bars. For this purpose, the experimental bond-slip law was used, obtained from the pull-out test having the same GFRP bar, same concrete cover and similar concrete properties as simulated RC slab. Since the slab failed for concrete crushing, the study assesses the importance of concrete compressive model selection on the numerical analysis results. Two different models were employed in the numerical analysis, in combination with three FE mesh densities. The main differences between the models comprise post-peak capacity and mesh dependency. The FE modelling strategy developed in the study was shown successful in reproducing the experimental outcome. Both concrete models showed convergence tendency when refining the mesh, whereas only one of them succeeded to reproduce the experimental results.