J.C.P.H. Gamage

Durability of CFRP-strengthened Concrete Members under Extreme Temperature and Humidity

Abstract Fibre reinforced polymer (FRP) systems have emerged as one of the most promising and affordable solutions for strengthening civil engineering infrastructure. Nowadays, this application is widely used in outdoor structures such as bridges, silos and towers. The major challenge in composites applications for outdoor structures is the long-term durability of bond between FRP and substrate under different environmental conditions. Elevated temperature and humidity are common issues that may have adverse effects on the polymer matrix, especially on thermosetting adhesives such as epoxies. This paper presents the results of long-term bond performance of carbon fibre reinforced polymer (CFRP) strengthened concrete members. CFRP- plated concrete specimens were exposed to combination of cyclic temperatures (20–50 °C) and 90% constant humidity. In addition to environmental exposure, some of the specimens were subjected to sustained loading. At the end of the exposure period, the residual strength was measured using single lap shear test method.

Durability performance of carbon fibre-reinforced polymer strengthened circular hollow steel members under cold weather

The use of circular hollow steel members has attracted a great deal of attention during past few years because of having excellent structural properties, aesthetic appearance, corrosion and fire protection capability. However, no one can deny the structural deficiency of such structures due to reduction of strength when they are exposed to severe environmental conditions such as marine environment, cold and hot weather. Hence strengthening and retrofitting of structural steel members is now very imperative. This paper presents the findings of a research program that was conducted to study the bond durability of carbon fibre-reinforced polymer (CFRP) strengthened steel tubular members under cold weather and tested under four-point bending. Six number of CFRP-strengthened specimens and one unstrengthened specimen were considered in this program. The three specimens having sand blasted surface to be strengthened was pre-treated with MBrace primer and other three were remained untreated and then cured under ambient temperature at least four weeks and cold weather (3 C) for three and six months period of time. Quasi-static tests were then performed on beams to failure under four-point bending. The structural response of each specimen was predicted in terms of failure load, mid-span deflection, composite beam behaviour and failure mode. The research outcomes show that the cold weather immersion had an adverse effect on durability of CFRP-strengthened steel structures. Moreover, the epoxy based adhesion promoter was found to enhance the bond durability in plastic range. The analytical models presented in this study were found to be in good agreement in terms of predicting ultimate load and deflection. Finally, design factors are proposed to address the short-terms durability performance under cold weather.