C形冷弯薄壁型钢承重组合墙体足尺耐火试验研究

Full-scale fire resistance tests on load-bearing C-shape cold-formed steel wall systems

冷弯薄壁型钢承重组合墙体抗火研究是多层冷弯薄壁型钢结构在我国推广应用的关键问题。文章共设计完成了十片C形冷弯薄壁型钢承重墙体足尺耐火试验,旨在经济高效地提高此类墙体耐火性能。试验同时考察了墙板类型、填充层情况、荷载水平等因素对墙体耐火性能的影响。结果表明:硅酸钙板存在高温爆裂现象,定向刨花板(OSB板)在墙体耐火试验中发生燃烧,玻镁板及蒸压加气轻质混凝土板(ALC板)则表现出优异的耐火性能;对于无空腔填充层的石膏板玻镁板冷弯薄壁型钢墙体,不同的荷载水平可能导致墙体产生不同破坏模式,进而影响墙体耐火时间;将硅酸铝棉布置在受火侧两层墙板之间(即外填充)可明显延缓墙体龙骨立柱表面升温,进而大幅度延长冷弯薄壁型钢承重墙体耐火时间。文中硅酸铝棉外填充的冷弯薄壁型钢墙体在0.65荷载比率下最长耐火时间达到165min,满足我国现行建筑设计防火规范的多层结构承重墙120min耐火极限要求。

Fire performance of Cold-Formed Steel （CFS） load-beating walls is the key problem encountered when popularizing and applying multi-storey CFS structures in China. This paper presents a detailed experimental investigation on ten full-scale load-bearing walls with C-shape CFS frame to efficiently improve their fire performance. The influences of the type of wall panels, insulation and load levels were also investigated. The results show that： ① The disadvantage of calcium silicate board is its bursting feature at high temperatures, oriented strand boards （OSB） may burn in the fire resistance tests of CFS walls, bolivian magnesium board and autoclaved lightweight concrete （ALC） board, however, exhibit excellent fire performance; ②When non-cavity insulated CFS walls with bolivian magnesium boards as base layer and gypsum plasterboards as face layer are exposed to a fire, different load levels may result in completely different failure modes and affect the fire resistance time of CFS walls; ③By using aluminum silicate wool as external insulation in which the aluminum silicate wool was located outside the CFS frame and sandwiched between two layers of boards on the fire side, a noticeable reduction of heat transfer to the surface of steel stud and a considerable improvement of fire performance of CFS walls can be achieved. For the present specimens of CFS wall with aluminum silicate wool as external insulation on the fire side, the maximum fire resistance time was 165 minutes when the load ratio was 0.65, satisfying the fire resistance requirement of 120 minutes for load-beating walls of multi-story structures in China.