Analytical Evaluation of Restraint Mechanisms in Precast Concrete Double Tee Floor Systems Subjected to Fire Loading

Abstract

The structural behavior of a precast prestressed concrete floor system subjected to fire is significantly influenced by the end restraint condition of its elements. Current design practice in the U.S. uses a dual classification for fire resistance of supporting members in floor and roof systems in buildings, depending upon whether these members are restrained or unrestrained at their ends. There are significant consequences in having a restrained versus unrestrained condition in terms the suitability of given section for a given span and loading condition. Chapter 6 of Design for Fire Resistance of Precast Prestressed Concrete published by the precast/prestressed concrete institute suggests that restraint comes primarily from end supports. In actual precast structures, restraint may come from a variety of effects in addition to the conditions that exist at the end supports of a member. For example, restraint may be provided by connections between adjacent members not subjected to fire