High-temperature axial tensile property and fire resisting performance of CFRP strand cable

High-temperature tensile tests and fire resisting performance tests were conducted on carbon fiber reinforced polymer (CFRP) strand cable, respectively, to identify axial tensile property deterioration of CFRP strand tendon (i.e., cable without initial tensile load) under 100–600℃ temperature range and determine fire resisting duration and ultimate temperature of CFRP strand cable with initial tensile load ratio from 0.2 to 0.8. High-temperature axial tensile property and fire resisting performance of different cables including CFRP and steel cables were compared to identify influence of non-uniform load distribution. The obtained results demonstrated that the dominate failure modes of specimen in both high-temperature tensile test and fire resisting performance test are tensile failure. Due to the degradation of mechanical property of resin matrix and bonding performance for resin matrix-fiber bundle interface exposed to elevated temperature, axial tensile strength of CFRP strand tendon degraded by 33.4% and 80.8% under 210℃ (glass transition temperature) and 600℃, respectively, compared to that under ambient temperature. Fire resisting duration of CFRP strand cables varied from 1.3 to 16.4 mins, indicating poor fire resisting performance. Reduction coefficient of bearing capacity for CFRP strand tendon decreased from 0.96 to 0.74 as temperature varied from 25 to 400℃, and then increased to 1.54 at 600℃. Compared to ribbed CFRP cable, CFRP strand cables with initial tensile load ratios ranging of 0.4 ∼ 0.8 (low ultimate temperatures) display worse fire resisting performance due to the prominent non-uniform load distribution among seven wires. Axial tensile strength and reduction coefficient of bearing capacity for CFRP strand tendon exposed to elevated temperature and fire resisting duration of CFRP strand cable and ribbed CFRP cable can be accurately predicted by the developed practical models.