Investigation on Behavior of Steel Cables Subject to Localized Fire in Large-Space Buildings

Abstract

Pre-tensioned steel cable is a crucial load-bearing component of steel structure, the fire behavior of which affects the overall performance of the structure. However, it presently lacks research and fire safety design method to consider steel cable members subject to localized large-space building fire. In this paper, the mechanical behavior of normal steel strand cable and full-locked steel cable under large-space building fire is investigated, to provide guidance for the fire safety design of steel cable. Firstly, the numerical model of temperature field of steel cables subject to large-space building fire was established and verified with the test results. Secondly, based on the verified temperature field model, the sequential thermal-mechanical coupling numerical model was established to study the fire behavior of steel cable, including temperature field, temperature gradient, failure mechanism, internal force and contact stress. Thirdly, the numerical method was adopted for the parametric analysis on the fire resistance of steel cables, considering the effect of temperature-field model, non-uniform fire, load ratio and span of steel cable. The following conclusions are obtained: 1) The average temperature can be taken to simplify the transverse temperature field due to the small amplitude of transverse temperature gradient of steel cable section; 2) Because of the size effect of steel wire, the overall temperature of normal steel strand cable is higher than that of full-locked steel cable under the same conditions of same nominal diameter and fire conditions, and the damage occurs earlier than that of full-locked steel cable under fire.