Debonding mechanisms of fibre reinforced polymer strengthened steel members.

Abstract

Applying Fibre Reinforce Polymer (FRP) to steel structures has been proved to be an effective method of strengthening. Experimentally, ageing steel structures such as bridge decks and composite beams which have been strengthened with FRP have shown lifetime extension and enhanced strength. Numerically, different approaches have been carried out to quantify the relationship between FRP and steel members in regard to the observance of the experimental works. This thesis contributes in term of quantifying the debonding mechanism of FRP strengthened steel members. First, a procedure in the derivation of the bond-slip (τ-σ) relationship is presented by combining the results of the experimental work with a numerical method developed specifically for this purpose. Secondly, the debonding mechanisms of FRP strengthened steel plates due to the yielding of steel is established by experimental and numerical works. Finally, a numerical method was developed to quantify the plate end debonding of a simply supported steel beam. A total of seventeen pull tests with different types of FRP lengths and adhesives were tested to quantify the (r-q) relationship. Another four steel plate tests were carried out to study the debonding mechanism of FRP allowing for the steel to yield. Three different numerical methods were developed to analyse the results obtained experimentally.