（中国建筑标准设计研究院，北京 100044）
［提要］楼板的耐火极限由楼板产生不能承受规定荷载而破坏的极限时间和楼板面平均温度上升到规定极限值的极限时间确定。美国规范规定了热膨胀受约束和无约束两种结构体系的耐火极限。给出了美国规范中不同结构体系和不同受约束条件下的板最小厚度和保护层厚度的要求。建议在吸收外国经验的基础上，补充我国规范对防火设计的相关规定。
［关键词］预应力混凝土空心楼板；耐火试验；耐火极限；约束条
件；最小厚度
Fire Resistance Design of Prestressed Hollow Floor System/Zhuang Guowei,Chen Youfan,Wu Yanyan(China Institute of Building Standard Design & Research,Bei
jing 100044,China)
Abstract:The fire endurance limit time of floor is determined according to the limit time that the floor can bear the specified load and damage and that the surface temperature reaches the specified value.The fire endurance limit times of restrained and nonrestrained hot expanding systems are set in  America code.The restrain conditions of different structural systems are introduced,and the minimum thickness of the floor and cover layer is presented in the code.It is suggested that some regulations about the fire endurance design in Chinese code should be added based on  abstracting the expereinces aboard.
Keywords:prestressed concrete; hollow floor; fire endurance test; limit time;restrain condition; minimum thickness