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确定无纤维或低纤维掺量的不同强度等级混凝土的爆裂临界温度,以及防止火灾时不同强度混凝土爆裂所需聚丙烯(PP)纤维或钢纤维最小掺量,对混凝土结构抗火设计具有重要意义。为此,对国内外大量高温爆裂试验研究结果进行分析,获得了爆裂临界温度与混凝土抗压强度(23~238 MPa)的关系曲线,发现混凝土抗压强度越高,爆裂临界温度越低。通过大量试验数据拟合得到了防爆裂PP纤维掺量、钢纤维掺量与混凝土抗压强度的关系曲线,发现随着混凝土抗压强度的提高,所需防爆裂PP纤维掺量呈线性增长,而所需防爆裂钢纤维掺量呈指数增长。按EN 1992-1-2:2004《欧洲混凝土抗火设计规范》建议值,PP纤维掺量为0.22%的防爆裂混凝土,火灾下仍可能发生爆裂;按所提出计算式计算的掺量,则可有效降低火灾下混凝土爆裂的风险。
Determining the critical burst temperature of concrete with different strength grades without any fiber or low fiber content and the minimum dosage of polypropylene (PP) fiber or steel fiber needed to prevent the burst of concrete with different strength during fire are of great significance to fire-resistant design of concrete structures . Therefore, a large number of domestic and foreign high temperature burst test results were analyzed and the relationship curve between the critical burst temperature and the compressive strength of concrete (23 ~ 238 MPa) was obtained. The higher the compressive strength of concrete, the lower the critical burst temperature. The curves of anti-burst PP fiber content and steel fiber content with the compressive strength of concrete were obtained through a large number of experimental data fitting. It was found that with the increase of compressive strength of concrete, the content of anti-burst PP fiber increased linearly, The required amount of explosion-proof steel fibers increased exponentially. According to EN 1992-1-2: 2004 “European Concrete Fire Design Code,” the recommended value, PP fiber content of 0.22% of the anti-burst concrete, fire may still burst; calculated by the proposed formula content, then Can effectively reduce the risk of concrete burst under fire.