Impact behaviour of hybrid GFRP-concrete beam under low-velocity impact loading

Abstract

The combination of two or more materials into a hybrid structural system is becoming increasingly important in the construction industry. The present study focusses on the design of a hybrid beam consisting of a rectangular hollow pultruded glass fiber reinforced polymer (GFRP) composite filled with concrete. The static flexural performance of the hybrid beam showed it has potential to be used as a structural element. However, the dynamic performance of the hybrid beam has yet to be assessed. If it is to be used as a railway sleeper or bridge girder, it could be subjected to low-velocity impact loading. The aim of this study therefore is to investigate the impact behaviour of the hybrid GFRP-concrete beam under low-velocity impact. This research comprised multiple experimental and numerical studies on the impact response of the hybrid GFRP-concrete beam subjected to low-velocity impact loading. The impact behaviour study of pultruded GFRP composites indicated that the impact energy level was the main factors that affected the response of the composite. The energy was absorbed mainly through the elastic-plastic deformation and failure mechanisms, such as matrix cracking and delamination. A numerical model was developed to analyse the development and propagation of the stress. The numerical investigation of the hybrid beam to static loading was conducted to validate the material models of the structural elements. The numerical results were highly consistent with the experimental data. Finally, the impact behaviour of the hybrid GFRP-concrete beam to the low-velocity impacts was analysed using experimentation and numerical simulations. The results indicated that the impact response could be divided into two stages, inertial resistance stage and dynamic bending resistance stage. In the former stage, the impact load was resisted completely by the inertial force. The majority of the impact energy was absorbed in the second stage. Multiple failure modes were presented in this stage, such as the punching failure and the global flexural cracks of the concrete, and the shear cracking on the pultruded composites.