广州东塔钢结构防火设计与施工研究

Research of fire protection design and construction methods of steel structure of Guangzhou East Tower

广州东塔采用了带伸臂桁架的巨型框架-核心筒体系,其中巨型框架由8根巨柱和6道环桁架组成,钢构件用量超过10万t,钢结构的防火问题突出。巨柱截面尺寸达到3 500mm×5 600mm,超出《建筑钢结构防火技术规范》(CECS 200∶2006)中砂浆防火适用范围,借助ANSYS软件进行模拟分析,论证了50mm厚砂浆防火性能可靠。对于转换梁耐火极限小于被承托柱耐火极限的问题,建议《建筑设计防火规范》(GB 50016—2014)中确定耐火极限表格中对于具体钢构件的分类应该考虑结构受力特点,根据其破坏产生的严重性来确定防火等级和耐火极限。通过理论分析证明工程实践中常用标准试验来确定钢梁防火涂层厚度的做法是偏于不安全的,应按照规范推荐公式计算确定。同时通过公式推导,给出基于规范经验公式推导出的钢梁防火涂层厚度快速判别方法。

Guangzhou East Tower adopts mega frame-core wall with outriggers as its main structural system. The mega frame is comprised of 8 mega columns and 6 belt trusses. The steel dosage exceeds 100 thousand tons and fire protection problem of steel structure is prominent. The mega column section is 3500 mm × 5600 mm that is beyond the application scope of mortar fire protection in Technical code for fire protection of building steel structure（ CECS 200∶ 2006）. ANSYS software was used to conduct simulation analysis to prove reliability of fire protection performance of mortar with 50 mm thickness. For the problem that fire resistance limit of the transfer beam is smaller than that of supported column,it was proposed that fire resistance limit determination table in Code for fire protection design of buildings（ GB 50016—2014） should consider mechanical properties of the structure in classification of concrete steel members,and that the fire rating and fire resistance limit should be determined according to the seriousness of its failure. By theoretical analysis,it is proved that it is not safe to determine the thickness of steel beam fireproof coating by standard test in engineering practice,and the thickness should be determined according to the formula recommended by the code. At the same time,formula was deduced to provide the fast discrimination method of the thickness of steel beam fireproof coating based on the code’s empirical formula.