Experimental investigation on high-temperature creep behavior of carbon fiber reinforced polymer cable

Both steady state-constant load and temperature (ST-CLT), and transient state-constant load and temperature (TR-CLT) tests were conducted on carbon fiber reinforced polymer (CFRP) cable in order to investigate the corresponding high-temperature creep behavior. The failure modes, creep strains and rupture times of CFRP cables exposed to high temperature were obtained in ST-CLT and TR-CLT tests, while the residual tensile strength and elastic modulus of specimens without rupture after high-temperature creep tests were determined by conducting high-temperature tensile tests. The variation law of high-temperature creep strains and rupture times of CFRP cable obtained from ST-CLT tests were compared to these of TR-CLT tests to identify the effect of temperature-load path. A practical model for characterizing the high-temperature creep behavior of CFRP cable was developed. Finally, the sustained stress levels and rupture times of specimens exposed to high temperature were analyzed to predict the high-temperature creep rupture stress level of CFRP cable. The obtained results indicated that the rupture morphology of high-temperature creep rupture specimens was the completely soft fiber bundles with "fluffy" pattern. The high-temperature creep strains of CFRP cables in ST-CLT and TR-CLT tests were highly depended on temperature, sustained stress level and time. The presence of pre-tension load before heating accelerated the damage of strength and stiffness for CFRP cable at high temperature, and the damage degree increased with the increasing sustained stress level and high-temperature. The developed practical models for CFRP cables under ST-CLT and TR-CLT conditions can accurately predict the high-temperature creep strains. In the fire resistant design of pre-stressed structures with CFRP cables, the effect of hightemperature creep rupture stress of CFRP cable was not negligible.