Long-term relaxation analysis of steel cables based on viscoelastic model

•A theoretical model for cable relaxation was derived and built based on viscoelastic theory.•The basic Kelvin chain model was optimized to identify the optimal relaxation model.•A 6000-hour cable relaxation experiment was designed and conducted.•The relaxation behavior of a cable net under different load conditions and over various time periods was calculated.•Research on both cable relaxation and cable net relaxation highlights the importance of studying relaxation mechanism Steel cables, renowned for their lightweight and high-strength properties, stand as ubiquitous building materials in large-span structures. Serving as crucial load-bearing elements, cables endure sustained tension throughout the structure's lifecycle. To further investigate the long-term relaxation characteristics of steel cables and provide more theoretical basis for structural relaxation calculations, this paper introduces a long-term relaxation constitutive model for steel cables, formulated through theoretical derivation, experimental validation, and data fitting techniques to establish time-dependent constitutive relationships. By employing the Bingham and Kelvin viscoelastic models, a relaxation model for steel cables is presented and optimized accordingly. Experimental investigations involve long-term tests on steel cables with three different sizes and detailed fitting analysis on collected internal force relaxation data. The findings emphasize the indispensability of structural relaxation behavior and the significance of altering internal forces, particularly in large-span cable-strut structures. The developed numerical model enables accurate simulation and prediction of long-term time-dependent performance in such structures, serving as a springboard for future studies in this domain.