FRP strengthening of 60 year old pre-stressed concrete bridge deck units

Over the past few decades fibre reinforced polymers (FRPs) have gradually gained recognition as an effective material for the strengthening of reinforced concrete (RC) structures. FRP strengthening techniques provide an attractive alternative to the existing cumbersome traditional bridge strengthening methods due to FRPs superior properties, such as lightweight, easy to install, and highly resistant to corrosion. FRP strengthening has been sought as an option for strengthening pre-stressed concrete deck unit bridges in Queensland, Australia. This paper presents an investigation in to the effectiveness of two different FRP strengthening techniques on increasing flexural capacity and flexural stiffness of pre-stressed RC deck units. Two different FRP strengthening schemes, one with adhesively bonded carbon FRP (CFRP) pultruded plates and another with adhesively bonded and mechanically fastened glass FRP (GFRP) I beam and adhesively bonded CFRP pultruded plates were investigated. Three 60 years old pre-stressed RC deck units taken from a bridge in Queensland, Australia were tested. One beam was tested as the control specimen, while the other two were strengthened with the two different FRP strengthening techniques. FRP strengthening using the two proposed systems found to increase the loads at serviceability limit by 10% and 31%, while ultimate strength was increased by 54% and 105%. A section analysis based on perfect composite section assumption was found to predict the moment curvature behaviour of the FRP strengthened specimens quite accurately. Existing design code methods were found to provide conservative design strength of the FRP strengthened pre-stressed RC deck units.