Description
Fabric reinforced cementitious matrix (FRCM) composite systems are being increasingly used to strengthen degraded reinforced concrete (RC) structures because of their high strength-to-weight ratio, ease of handling, reduced costs, and non-combustibility properties. Although these advantageous characteristics, the information available about their mechanical response when subjected to elevated temperatures is still very limited. This paper presents a numerical study that aimed at providing a better understanding about the bond behaviour between a polypara-phenylene-benzo-bisthiazole (PBO) FRCM system and concrete at elevated temperatures. To this end, three-dimensional finite-element (FE) models were developed to simulate experimental steady-state single lap direct shear (DS) tests previously performed by the authors on PBO FRCM-to-concrete joints tested at the following temperature: 20, 85, 150 and 230 ºC. The main objectives were two-fold: (i) to evaluate the influence of the temperature on the bond response between the PBO-FRCM and the concrete substrate; and to (ii) provide a better understanding about the evolution of the stress fields in the composite and at the interface with concrete. The results obtained showed that the FE models were able to reproduce with relatively good accuracy the experimental data, specifically regarding the bond stress vs. slip curves, and the reduction in bond stress and bond stiffness with temperature. The numerical models developed in this work can be used as supporting tools to the fire design of FRCM strengthened RC structures, allowing the optimisation of the strengthening system geometry.
