Experimental study and numerical prediction of the bond response of NSM CFRP laminates in RC elements under sustained loading

Abstract

This paper presents a study into bond behaviour under sustained loading of Near-Surface Mounted (NSM) Carbon-Fibre Reinforced Polymers (CFRP) concrete joints, through an experimental programme and a numerical analysis. The experimental programme consisted of eight NSM CFRP-concrete pull-out specimens tested under sustained loading and laboratory conditions (20 °C and 55%HR) inside a climatic chamber. Previously, the instantaneous bond behaviour of the NSM CFRP-concrete joint was studied using 18 specimens tested until failure. Furthermore, the tensile behaviour of the adhesive under instantaneous and sustained loading was studied at different loading levels under the same environmental conditions. Finally, a numerical procedure was proposed to predict the bonded joint response under sustained loading. A creep coefficient and a strength reduction factor were applied to the instantaneous bond-slip law to simulate the degrading effect the sustained loading had on the behaviour of the bonded joint. Good agreement between the experimental and numerical results was obtained for the tested parameters, however, further research needs to be carried out in order to extrapolate this methodology to other cases