Response surface metamodel-based performance reliability for reinforced concrete beams strengthened with FRP sheets

This paper presents the performance reliability of reinforced concrete beams strengthened with fiber reinforced polymer (FRP) sheets, including structural fragility. Emphasis is placed on the development of effective strains that can represent FRP-debonding failure. The reliability predicted by a conventional standard log-normal cumulative probability density function and by the proposed response surface metamodel (RSM) combined with Monte-Carlo simulation (MCS) is employed to assess the contribution of physical attributes to debonding failure. The models are constructed based on a large set of experimental database consisting of 230 test beams collected from published literature. Another aspect of the study encompasses the effect of various RSM parameters on the variation of effective strains, such as FRP thickness (tf), steel reinforcement ratio (p), concrete strength (f′_c), beam height (h), beam width (w), span length (L), and shear span (a). The mutual interaction between these parameters indicates that those related to beam geometry (i.e., L, w, h, and a parameters) and the t_f parameter are significant factors influencing the effective strain of FRP-strengthened beams.