Numerical thermal analysis of structural masonry in fire situations: thermal insulation between adjacent rooms

Abstract Fire situations must be considered in structural design to minimize risks to the safety of buildings, since high temperatures ultimately result in the decrease of the mechanical properties of building materials and lead to the spread of flames to adjacent rooms. However, Brazilian standards do not provide design procedures for evaluating structural masonry at high temperatures, therefore engineers usually apply foreign standards, which are based on the thermal properties of the materials used in their countries. This study aims to evaluate the thermal behaviour of concrete masonry walls in fire situations by means of numerical analysis, taking the experimental results presented in Dupim (2019) as reference. The thermal properties of the materials in the numerical model were calibrated according to the Eurocode, and temperature increases on the masonry surfaces were simulated by using temperature-time curves obtained in experimental tests. The numerical results are in good agreement with the experimental measurements, which were carried out at various points in the masonry cross section, with maximum temperature differences below 10%. The fire resistance of a 14 cm-thick masonry wall, according to the thermal insulation criterion, was equal to 60 min in the numerical analysis, which is close to the experimental result of 62 min taken as reference.

摘要：火灾工况必须纳入结构设计考量以降低建筑安全风险，因为高温最终会导致建筑材料力学性能劣化，并引发火势向相邻房间蔓延。然而，巴西现行标准并未提供高温下结构砌体的评估设计规程，因此工程人员通常采用基于本国材料热工特性的国外标准。本研究以Dupim（2019）发布的试验结果为参照，采用数值分析方法评估火灾工况下混凝土砌体墙的热工性能。本数值模型中材料的热工参数依据欧洲规范（Eurocode）进行校准，并通过试验获取的温度-时间曲线模拟砌体表面的温升过程。数值计算结果与砌体截面多点布设的试验实测值吻合良好，最大温差小于10%。依据隔热性能判定准则，数值分析得到14cm厚砌体墙的耐火极限为60分钟，与参照试验得到的62分钟结果相近。