EXPERIMENTAL INVESTIGATION ON MECHANICAL PROPERTIES OF GRADE 1670 STEEL WIRES AT AND AFTER ELEVATED TEMPERATURE

Grade 1670 steel wires were selected for elevated-temperature and post-elevated-temperature tensile tests. The test data were analyzed through comparison with the results in existing literatures. The elevated-temperature test results indicate that, mechanical properties of the steel wires degraded with the increase of temperature. The mechanical behaviors of the steel wires degraded rapidly at the temperature exceeding 300°C; and the load-carrying ability was substantially lost when the temperature increased up to 700°C. In the post-elevated-temperature test, the modulus of the steel wire was substantially completely recovered after cooling from the elevated temperatures; the nominal yield strength and ultimate strength degraded obviously after cooling from the temperature exceeding 400°C. Based on the test data, the reduction factors of the mechanical properties at and after elevated temperatures were fitted as a function of the temperature, and constitutive models of the steel wires were established. The results can provide technical supports for the analysis of fire performance of prestressed cable support structures, and their post-fire repair.