MATHEMATICAL CALCULATION OF INSTANTANEOUS TENSION FOR STEEL CABLES IN FIRE TEMPERATURE HISTORY

Based on the equilibrium differential equation of cable at ambient temperature, considering the geometric distortion with thermal stress coupling, the temperature distribution along cables and the non-linear temperature-dependent material properties for steel cables, formulas for the calculation of horizontal tension in cables subjected to fire under line loads and point loads are developed. In the mean time, the fire limit state of steel cables is derived from the equation of horizontal tension. Additionally the nonlinear numerical model for the analysis of the cable fire performance is fit to the analytical calculation precisely. This study provides a theoretical reference for a further research on the fire-resistance of cable structures.