Fire Resistant Steels...

Fire Resistant Steels Steel is inherently a noncombustible material. It loses strength when heated sufficiently.  Steel structural properties and its yield strength considerably decrease when it is heated to temperatures seen in a fire scenario. The critical temperature of a steel structural member is the temperature at which it cannot safely support its load. Building codes and structural engineering standard practice defines different critical temperatures depending on the structural element type, configuration, orientation, and loading characteristics. The critical temperature is often considered the temperature at which its yield stress has been reduced to 60 % of the room temperature yield stress. Fire is a chemical phenomenon that occurs as a result of thermal processes. When a steel section is exposed to a fire then the level of temperature increase on the face of steel section depends on thermal inertia, exposure of surface area and the protective coating. As the rate and amount of heat flow from the fire environment to steel section increase, the temperature, and thus the risk of failure for the steel section also increases. Since the steel has a very high thermal conductivity, exposed surface of the steel section easily transmits the conveyed heat from the fire source to the other members of the whole structure in a short period of time. Heat is transmitted in between the steel sections from high temperature sections to low temperature sections by way of conduction, radiation or convection modes. Steel sectional properties and its yield strength considerably reduce as it absorbs heat upon exposure to a high temperature level. A steel structural member may easily collapse during a fire if the temperature is allowed to reach a critical value. The fire resistance of the steel member is related to some important factors including the section size, the perimeter...