钢交错桁架结构和钢框架结构抗火性能分析与对比

 钢交错桁架结构是在钢框架结构基础上演变而来的一种新型结构体系，虽然在国外已有许多工程应用实例，但在中国的应用尚处于起步阶段。为了研究此种结构体系的抗火性能，为制定相应的防火设计规范提供理论依据，根据结构设计和传统防火设计理论，对钢交错桁架结构体系和钢框架结构体系的结构设计方案和防火方案分别进行了研究，比较了两种结构体系的用钢量和防火涂料用量，探讨了火灾情况下两种结构体系可能发生的多米诺坍塌效应，并进行改进设计与分析。结果表明，在相同极限承载力和耐火极限下，交错桁架结构和框架结构相比，虽然能够大大降低用钢量，但是增加了防火涂料用量，火灾时更容易发生多米诺坍塌效应，减弱了其经济优势。传统结构防火设计的拓广应用不能满足其防火要求，需要制定相应的防火设计规范，提出适合此种结构的防火设计方法。

Comparison and Analysis of Fire Resistance Between Steel Staggered-truss System and Steel Frame Structure

The Steel Staggered-Truss Framing System(SSTFS) is a new type of structural system, which is developed on the basis of the Steel Frame Structure (SFS). Though there are already a large number of examples of engineering applications of SSTFS in the world, in China, its application is still in an initial stage. In order to study its fire resistance performance and to provide a possible theoretical foundation for related codes of fire protection, the structure design strategy and the fire protection strategy of SSTFS and SFS are studied in this paper based on the structure design and traditional fire protection design theories. The amounts of steel and fireproof coatings used are compared and the potential domino collapse effects of two kinds of structures exposed to fire are studied. Results show that with the same ultimate bearing capacity and fire resistance, SSTFS could greatly reduce the amount of steel, as compared to SFS. However, it would need larger amount of fireproof coatings, and the domino collapse is more likely to occur during a fire, which reduces the economic advantages of SSTFS. As the traditional fire protection design can not be directly extended for the fire protection of SSTFS, the corresponding fire protection strategy must be established and a new fire protection design method, suitable for the structure of SSTFS, should be found.