Effect of temperature on the mechanical properties of low relaxation seven-wire prestressing strand

This paper presents results from experiments on the effect of temperature on the mechanical properties of low relaxation seven-wire prestressing strand. A set of steady-state tensile strength tests are carried out on prestressing strands and reinforcing bars at various temperatures. Data from these tensile strength tests is utilized to derive stress-strain response, yield strength, tensile strength, elastic modulus, and rupture strain of prestressing strand and reinforcing bars in 20–800 °C temperature range. Results obtained from these property tests indicate that prestressing strand experiences higher strength degradation than that of reinforcing steel bar throughout the temperature range. In addition, presence of preload on prestressing strand slightly increases the temperature induced rate of strength degradation beyond 450 °C. Results from these mechanical property tests are utilized to propose empirical relations for expressing variation of mechanical properties of low relaxation seven-wire prestressing strand as a function of temperature.