Study on mechanical properties of locked coil wire rope under and post fire

Abstract

• Carry out the static tensile test of the locked coil wire rope under and after high temperature. • Obtain the mechanical properties and failure mode of locked coil wire rope under and post fire. • The reduction law of locked coil wire ropes under and post fire is obtained. • Compared with the existing research, the failure mechanism of cable is studied. • The prediction method of temperature dependent mechanical properties is proposed. As a new type of strand with excellent performance, a locked coil wire rope has been commonly used in all types of prestressed spatial structures. Owing to its unique section, it has a different temperature distribution, bearing mechanism, and failure mode from a traditional cable. In this study, static tensile tests of locked coil wire rope specimens were conducted under and after elevated-temperature treatments, and reduction laws of the mechanical properties of the strand were obtained. Based on the test results, a method for prediction of the mechanical properties of locked coil wire ropes under and after elevated-temperature exposure was developed. The research showed that the failure of a locked coil wire rope is ductile failure. Its ultimate strength begins to decrease when the heating temperature exceeds 200 °C. When the temperature reaches 400 °C, the strength of the strand is lower than 50 % of that at room temperature. The heat treatment process reduces the strength and ductility of the strand. When the heating temperature of a strand reaches 400 °C, it should be replaced in time after a fire. The research results provide a theoretical basis for fire resistance and post fire assessment of prestressed structures.