TIME DEPENDENT BEHAVIOR OF RC MEMBERS STRENGTHENED WITH FRP LAMINATES

This study attempts to develop a fundamental understanding of the time-dependent behavior of reinforced-concrete beams strengthened with fiber reinforced plastic laminates. The paper describes an analytical procedure for the deformation of cross sections based on the age-adjusted effective modulus method for concrete, Findley's (1960) model for composite materials, and a stress relaxation procedure to yield the cross sectional stresses and strains as a function of time. Also presented are parametric studies asesssing the effect of the type and area fraction of composite material, and the area fraction of steel reinforcement on the long term response of strengthened elements. The analytical model is used to predict the deflections of concrete beams strengthened with FRP laminates of different thicknesses.

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