Application of Inverse Analysis to Thermal Contact Resistance between very Rough Nonconforming Surfaces

A method to determine the contact conductance at the interface between steel and concrete under high temperature conditions, typical of enclosure fires, using experimental measurements and inverse heat conduction analysis is presented. This method is adopted because the interface under investigation is formed by very rough non-conforming surfaces and there are no data or mathematical models capable of describing such an interface. A specimen representing a square steel tube filled with concrete is heated in a modified electrical furnace to temperatures comparable to those observed in structural elements exposed to fire, and temperature-time histories in two-second increments are recorded at ten locations. The results are used to obtain a correlation representing averaged contact conductance for the steel-concrete interface of square steel tube filled with non-reinforced concrete as a function of temperature.