Fire Safety Science Digital Archive

Tensile membrane action is a load carrying mechanism in reinforced concrete floors at very large deflection. Under this action, the load carried by the reinforced concrete floor can be many times higher than the design load carrying capacity determined at small deflections. Recent full scale fire tests and fire accidents in steel-framed buildings with reinforced concrete floors have identified tensile membrane action as the main load carrying mechanism. This mechanism is able to transfer the applied loads on the floor to the supporting columns when the supporting steel beams to the floor are damaged and have lost their load carrying capacities. The understanding of tensile membrane action in reinforced concrete floors has a significant implication for the fire protection of steel-framed buildings with reinforced concrete floors. This is because the supporting steel beams may be allowed to fail without endangering the safety of the whole building. Consequently, fire protection to these steel beams can be reduced or eliminated. This paper describes in some detail an analytical procedure developed by the author for predicting tensile membrane action in reinforced concrete floors. An example is given which shows how to use this method to determine the tire resistance of a steel-framed building.