Quantifying High Temperature–Induced Breakage Instant of Prestressing High-Strength Steel Wire

Abstract

The danger of high-strength steel wire (HSSW) under high temperatures is twofold. One is the significant degradation of the material properties of high-strength steel (HSS), which has been extensively studied. The other, which appears to be important in some issues but has not been investigated, is that the breakage of HSSW is very hazardous from the perspective of dynamics because enormous stress can be released within a very short time. This paper reports an experimental study to quantify the transitory breakage instant. HSSW specimens with different section dimensions (intact 7.0 mm, intact 5.3 mm, and damaged 7.0 mm) were heated to failure under various steady prestressing forces at two constant temperature rates (50°C/min and 25°C/min). High-speed sampling technology was applied to capture the axial force variation before and during the rupture process. Through data regression, the breakage instant caused by high temperature was quantified by three elements, i.e., the ratio of initial force of breakage to prestressing force, the time history, and the breakage duration. The results showed that the parametric characteristics of rupture instant is dominated by the ratio of the prestressing force to the ultimate force at room temperature. In addition, the extent of the initial section damage has a positive relation with the initial force which indicates the start of the breakage.