Experimental Study of Stress Relaxation Performance of Steel Cables at Room Temperature

Abstract

Most previous stress relaxation tests were based on steel wires and steel strands. This test performed 1,000 h of stress relaxation test on stainless steel cables and Galfan-coated steel cables with diameters of Ø14, Ø20, and Ø26 mm. Three different initial tension levels were tested, and three control values of 30%, 50%, and 70% of the ultimate tensile strength of the cable were used as the load control points. The stress relaxation tests were carried out in a factory building, and the temperature was not strictly controlled. The stress relaxation of the cable is the stress relaxation under the combined action of temperature relaxation, stress relaxation, and time relaxation. To make the research more valuable, the thermal expansion coefficient of the cable was used to eliminate the influence of temperature on the stress relaxation test, and the data were adjusted to correspond to 30°C. The test results were analyzed, and formulas for calculating the tension loss of steel cables were established. The results showed that the exponential equation of time logarithm can better express the relation between tension loss and time. The relation between the coefficients and the initial tensile force was established. This test also compared the relaxation properties of stainless steel cables and Galfan-coated steel cables. For steel cables with the same initial tension level and the same diameter, the Galfan-coated steel cables had much larger relaxation rates than the stainless steel cables.