Comparative Study of Ultimate Bond Strength Models for FRP-to-Steel Bonded Joints

This paper presents a comparative study of current ultimate bond strength models for fiber reinforced polymer (FRP)-to-steel bonded joints. A database that includes the test results of 106 single and 93 double lap joints was assembled from the open literature for this comparison. Comparative results show that Xia and Teng's and Hart-Smith's models have the highest accuracy for predicting the ultimate bond strengths of single and double lap joints, respectively. Current ultimate bond strength models for single or double lap joints have some applicability to both single and double lap joints. Xia and Teng's model has the best performance for predicting the ultimate bond strengths of both single and double lap joints. However, the predictions by Xia and Teng's model have a large deviation for double lap joints and for joints whose adhesives have trilinear bond-slip behavior. Based on comparative results, an improved ultimate bond strength model for both single and double lap joints is proposed. The proposed model further considers the effects of the joint type, the stiffness ratio of the double lap joint and the bond-slip behavior of the adhesive. The comparison between model predictions and test results indicates that the improved model is more accurate and applicable than current models for both single and double lap joints.