Abstract
This paper presents an innovative method of prestressing carbon fibre reinforced polymer (CFRP) plates used as externally bonded reinforcement for flexural strengthening of reinforced concrete (RC) beams. The proposed method aims to achieve self-anchorage of the prestressed CFRP plate and thus eliminate the need for conventional mechanical anchorage at its ends. Experimental tests of RC beams in four-point bending were conducted to investigate the strengthening efficiency of the self-anchored prestressed CFRP plate. The experimental results showed that using the self-anchored prestressed CFRP significantly improved the flexural performance of the strengthened beam in terms of bending stiffness, crack widths, and load-carrying capacity. The utilisation ratio of the prestressed CFRP plate reached 81% at its debonding. Numerical analyses using nonlinear finite element (FE) method were conducted to model the tested specimens. Based on the reliable simulation of flexural cracks and crack-induced CFRP debonding, parametric studies were conducted using FE analyses, in order to investigate the effect of prestressing levels and the CFRP plate’s stiffness on the flexural behaviour. Recommendations were then made for selecting a proper prestressing level and the mechanical properties of CFRP plates.
Highlights
Using carbon fibre reinforced polymer (CFRP) plates as externally bonded reinforcement (EBR) has become a commonly accepted tech nique for enhancing the flexural capacity of deficient structures made of different materials, including concrete [1,2,3,4], steel [5,6,7,8] and timber [9]
Current flexural tests showed that using bonded CFRP plates effectively improved the flexural stiffness and load-carrying capacity of specimens B2 and B3 in comparison with the reference specimen B1, whereas the ultimate deflection at failure was reduced after the CFRP-strengthening
This paper investigated a novel technique to prestress CFRP plates used as EBR for flexural strengthening of reinforced concrete (RC) beams
Summary
Using carbon fibre reinforced polymer (CFRP) plates as externally bonded reinforcement (EBR) has become a commonly accepted tech nique for enhancing the flexural capacity of deficient structures made of different materials, including concrete [1,2,3,4], steel [5,6,7,8] and timber [9]. Capacity, their application might be associated with several drawbacks: (a) labour-intensive installation process involved with cutting and dril ling concrete to install the metallic plates and bolts; (b) steel anchors’ vulnerability to corrosion during the service life; (c) restrictions in the inspection of anchors due to lack of access (i.e. anchors cannot be opened); (d) sensitivity to the quality of workmanship; and e) aesthetic aspects and vandalism issues. To avoid these problems, Stocklin and Meier [29] suggested a gradient anchorage method to self-anchor prestressed plates. Based on the FE analyses, parametric studies were conducted to further investigate the effect of prestressing levels and the elastic modulus of the CFRP plate on the flexural behaviour of the strengthened RC beams
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