Mechanical properties of pultruded high-temperature-resistant carbon-fiber-reinforced polymer tendons at elevated temperatures

Abstract

Cable roof structures built with carbon-fiber-reinforced polymer (CFRP) cables instead of steel cables, which are called CFRP cable roofs, represent a new structure with great development potential. However, as one of the main stressed components of structures, CFRP cables are required to have better fire resistance. In this paper, the fire resistance of a type of high-temperature-resistant (HTR) CFRP tendon is studied. A total of 39 specimens with a diameter of 5 mm are performed in this study, among which 33 specimens are for steady-state tensile tests and 6 for transient state tests. Steady-state tensile tests are conducted over in the 20–600 °C range, and transient state tests are conducted for stress levels ranging from 0.19 to 0.57. The steady-state test results show that HTR CFRP tendons have excellent room-temperature and high-temperature mechanical properties. The strength remained 78% at 200 °C and the elastic modulus remained 82% at 300 °C, indicating the effectiveness of high-temperature resistant resin matrix. When the temperature reaches 600 °C, the strength remains 19%. The transient state test results show that the high initial stress (stress level of 0.57) can aggravate damage to CFRP tendons at high temperatures. Finally, a high-temperature equation is obtained for the temperature dependence of the strength and modulus of HTR CFRP tendons by developing a mathematical model that is fitted to the test data.