火灾下钢筋混凝土梁结构高温力学性能数值模拟研究

Numerical Simulation Study on the High-Temperature Mechanical Properties of Reinforced Concrete Beam Structures under Fire Conditions

摘要: 为探究火灾作用下钢筋混凝土(Reinforced Concrete beam，简称RC柱)梁高温力学性能的演化规律，为其防火设计与性能评估提供科学依据，本文采用ABAQUS有限元软件，基于顺序热力耦合方法建立RC梁数值模型，通过与试验数据对比验证模型准确性。随后以受火方式、纵筋直径、升温时间及梁截面尺寸为关键变量，系统开展火灾下RC梁跨中挠度数值模拟分析，重点研究不同影响因素对RC梁跨中挠度的影响规律。研究表明，受火面越多、纵筋直径越小、升温时间越短、截面尺寸越小，RC梁跨中挠度增长越快、后期挠度值越大；而温度梯度引发的热胀差异及材料强度退化是挠度产生的主要原因。

Abstract: To explore the evolution law of the high-temperature mechanical properties of reinforced concrete (Reinforced Concrete beam, abbreviated as RC beam) beams under fire conditions, and to provide a scientific basis for their fire protection design and performance evaluation, this paper uses the ABAQUS finite element software to establish a numerical model of RC beams based on the sequential thermal coupling method. The accuracy of the model is verified by comparing with experimental data. Subsequently, taking the fire exposure mode, longitudinal reinforcement diameter, heating time, and beam cross-sectional size as key variables, a systematic numerical simulation analysis of the deflection at the mid-span of RC beams under fire conditions is carried out. The influence laws of different influencing factors on the mid-span deflection of RC beams are mainly studied. The research shows that the more fire-exposed surfaces, the smaller the longitudinal reinforcement diameter, the shorter the heating time, and the smaller the cross-sectional size, the faster the mid-span deflection of the RC beam increases and the larger the final deflection value. The main reasons for the deflection are the thermal expansion differences caused by the temperature gradient and the degradation of material strength.