EXPERIMENTAL STUDY AND THEORETICAL ANALYSIS ON THE FIRE RESISTANCE OF CABLE TRUSS STRUCTURES

Cable structures are widely used in larger span structures. The study of fire resistance of cable structures can provide practical methods for their fire resistance design. Cable structures are composed of multiple steel wires, and their heat transfer mechanism is relatively complicated. Heat transfer calculation is the basis of the fire resistance design of cable structures. In this study, temperature field tests were firstly conducted on various diameter cable specimens with intumescent coatings, based on which the temperature distribution and development of cable structures were investigated. Based on the test results, a finite element analysis model for the temperature filed of cable structures considering cavity radiation heat transfer was proposed, and the calculated results agree well with the test results. A fire resistance analysis model of cable truss structures was proposed and the mechanical properties and failure modes under high temperature were studied with the model. The results show that due to the thermal resistance between steel wires, the temperature rise at the central test points lags behind that in the peripheral, and this lag effect become more obvious with the increase of cable diameter. When subjected to fire, the stable cable first slacks and the stress decreases quickly to zero, and finally the bearing cables broke, resulting in the failure of the cable truss structure. As the load increases, the fire resistance of the cable structure decreases. When the prestress of the stable cable increases, the fire resistance of the cable truss structure remains unchanged, while the time for the cable truss structure to maintain a good working condition increases.