Mechanical properties under high-temperature and fire resistant limit of carbon fiber reinforced polymer cable

Abstract

To fully understand the fire resistant performance of Carbon fiber reinforced polymer (CFRP) cable with high-temperature-resistant resin matrix, both steady state and fire resistant tests were conducted on specimens. The degradation law for axial tensile properties of CFRP cable without pre-tension load under high temperature from 100 to 600 °C was uncovered in steady state tests in order to develop the corresponding constitutive models. Failure temperatures and fire-resistant limits of CFRP cables with pre-tension load heated following the equivalent standard temperature rise process were obtained in fire resistant tests, and were compared to the predicted results using the developed constitutive models and finite element thermal analysis. Then, a practical calculation model for determining fire-resistant limit of CFRP cable was developed and the effect of temperature-load path on mechanical properties of CFRP cable under high temperature was identified. The obtained results demonstrate that the rupture morphologies of tensile failure of CFRP cable in both steady state and fire resistant tests varied with the failure temperature. In steady state tests, mechanical properties of CFRP cable at high temperature are closely correlated with glass transition temperature Tg = 211.6 °C and decomposition temperature Td = 409.6 °C, and effect of high temperature on elastic modulus is more significant than that of tensile strength. In fire resistant tests, failure temperature and fire resistance limit of CFRP cable gradually decreased as pre-tension ratio increased. The fire resistance limits of CFRP cables with pre-tension ratios of 0.2 ∼ 0.6 vary from 3.26 to 15.40mins and its fire performance are very poor. The presence of pre-tension load with ratio R from 0.6 to 0.7 resulted in acceleration of damage for CFRP cable at high temperature. The developed constitutive models of mechanical properties under high temperature and the practical calculation model of fire-resistant limit with high accuracy can be adopted in fire resistant design and analysis of the structures with CFRP cable.