Fire tests and subsequent bending tests of four reinforced concrete (RC) beams were performed. Based on these tests, the post-fire performance of RC beams was further studied using finite-element simulation through reasonable selection of suitable thermal and thermodynamic parameters of steel and concrete materials. A thermodynamic model of RC beams with three sides under fire was built using finite-element analysis (FEA) software ABAQUS. The FEA model was validated with the results of fire tests. Different factors were taken into account for further parametric studies in fire using the propsed FE model. The results show that the main factors affecting the fire resistance of the beams are the thickness of the concrete cover, reinforcement ratio of longitudinal steel, the fire exposure time and the fire exposure sides. Based on the strength reduction formula at high temperature of steel and concrete and four test results, an improved section method was proposed to develop a calculation formula to calculate the flexural capacity of RC beams after fire. The theoretical calculation method proposed in this paper shows good agreement with FEA results, which can be used to calculate the flexural capacity of RC beams after fire.

中文翻译：

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火后钢筋混凝土梁残余抗弯承载力有限元分析及计算方法

对四根钢筋混凝土 (RC) 梁进行了防火测试和随后的弯曲测试。在这些试验的基础上，通过合理选择合适的钢筋和混凝土材料的热力学参数，利用有限元模拟进一步研究了钢筋混凝土梁的火灾后性能。使用有限元分析（FEA）软件ABAQUS建立了三边受火钢筋混凝土梁的热力学模型。FEA 模型通过火灾测试结果进行了验证。使用所提出的有限元模型对火灾中的进一步参数研究考虑了不同的因素。结果表明，影响梁耐火性能的主要因素是混凝土保护层厚度、纵筋配筋率、受火时间和受火边数。基于钢筋和混凝土的高温强度折减公式和4次试验结果，提出了改进截面法，建立了钢筋混凝土梁火灾后抗弯承载力的计算公式。本文提出的理论计算方法与有限元分析结果吻合较好，可用于计算钢筋混凝土梁火灾后的抗弯承载力。