Tensile Strength of GFRP Bars Under Sustained Loading in Concrete Beams

摘要

Glass fiber reinforced polymer (GFRP) bars were placed under load in concrete beams for periods of time as long as three years in natural and harsh environments. Following flexural loading, the bars were carefully extracted from the beams and tested in order to evaluate residual tensile properties. It was found that the tensile strength decreased in the highly aggressive conditions but not in the natural conditions. The modulus of elasticity and ultimate strain did not change appreciably in any of the four conditions. Analysis of selected bars using thermo-mechanical analysis indicated only slight effects of conditioning on glass transition temperature and transverse coefficient of thermal expansion. Energy dispersive x-ray spectroscopy indicated no signs of damage, loss of cross section, orchange in material composition of the bars.