Punching shear behaviour of pultruded FRP cellular panels with polymer concrete toppings: an experimental investigation

Abstract This paper details an experimental investigation into the behaviour of pultruded glass fibre-reinforced polymer (GFRP) hollow section panels subject to concentrated load, such panels are commonly used in highway bridge decks. In addition to plain GFRP panels, the influence of polymer concrete overlays acting compositely with the GFRP section is also explored. As comparatively thin-walled elements, GFRP components can be vulnerable to localised failures that may arise from concentrated loads. The strategic use of concrete toppings, acting compositely with the GFRP component, can enhance the section’s resistance to such local failures as well as enhancing the overall flexural capacity and stiffness. Currently, no punching shear data on closed form pultruded composite GFRP-concrete deck components are readily available in the existing literature. To address this, six pultruded GFRP deck components (338 mm x 600 mm x 80 mm) were investigated experimentally under concentrated, monotonic load, including two plain panels, two with a 15 mm polymer concrete topping and two with a 30 mm topping. In comparison to the plain GFRP panel, a 67% and 280% increase in ultimate load capacity was observed with addition of the 15 mm and 30 mm polymer concrete topping respectively. In parallel, corresponding increases in initial stiffness of 60% and 199% up to the peak load were observed, demonstrating a good degree of composite action. In the case of the panels with toppings, the onset of punching shear was delayed in comparison to plain panels. For all the cases examined with toppings, no significant de-bonding of the polymer concrete from the GFRP substrate was observed, indicating the suitability of directly bonded toppings in this scenario.