钢筋活性粉末混凝土梁抗火性能研究

Reactive powder concrete (RPC) is a new material with high strength, high toughness and excellent durability, which has a good application prospects in the field of civil engineering. For the safety of RPC structure reducing drastically at fire, firstly, the changes of thermal parameters (thermal conductivity, heat capacity and linear expansion coefficient) with temperature are revealed through experiments, and the freedom expansion deformation, transient thermal strain and high temperature creep are obtained by the test of loading under constant temperature and elevating temperature under constant loading, and then the RPC temperature-stress constitutive relationship is established. Secondly, the fire resistance experiment of reinforced RPC beam is completed, and the effects of load level, reinforcement ratio, cover thickness and fire duration on the bearing capacity and deformation of RPC beam are studied. Through the mechanical experiment of RPC beam after fire, the ultimate load capacity and load-deformation curve are acquired, and the formula to calculate the bearing capacity in normal section of reinforced RPC beam after fire is proposed. Finally, based on the thermal parameters and the RPC temperature-stress constitutive relationship, The numerical simulation of catastrophic behavior of reinforced RPC beams under fire is performed to study the effect of test parameters on the bearing capacity, deformation, section stress and failure mode, and the comparative analysis is conducted with the experimental results, which provide a reference for improving the safety of RPC beams under fire.

活性粉末混凝土(RPC)是一种高强度、高韧性、高耐久性的新型材料，在土木工程领域具有较好的应用前景。针对火灾下RPC结构安全性急剧降低的问题，首先，通过试验揭示导热系数、比热容、线膨胀系数等热工参数随温度的变化规律，通过恒温加载和恒载升温试验，获得RPC的自由膨胀变形、瞬态热应变和高温徐变，建立RPC温度-应力本构关系；其次，对钢筋RPC简支梁进行抗火试验，考查荷载水平、配筋率、保护层厚度和火灾持续时间对梁承载力和变形的影响，通过火灾后RPC梁力学性能试验，获得RPC梁极限承载力、荷载-变形曲线，提出火灾后钢筋RPC简支梁正截面承载力计算公式；最后基于RPC热工参数值和温度-应力本构关系，实现火灾下钢筋RPC梁灾变行为的数值模拟，研究各试验参数对梁承载力、变形、截面应力的影响规律，研究梁的破坏模式，并与试验结果进行对比分析，为提高火灾下RPC梁的安全性提供参考。

通过热工性能试验，揭示了温度和钢纤维掺量对RPC导热系数、比热容、线膨胀系数等热工参数的影响，并建立了相关计算公式，为RPC结构构件温度场数值分析提供必要的数据参考。通过恒温加载和自由膨胀试验，获得了RPC的自由膨胀变形，建立了RPC温度-应力本构关系，为火灾下RPC结构构件受力分析提供了依据。完成了8根钢筋RPC简支梁明火试验，考查了荷载水平、配筋率、保护层厚度对梁变形的影响，发现同等条件下，保护层厚度对RPC简支梁抗火性能影响显著，防火涂料可有效改善火灾下梁的破坏程度。完成了4根常温、8根火灾后RPC简支梁受弯试验，测得了梁的极限承载力和荷载-变形曲线，建立了常温下和火灾后钢筋RPC简支梁受弯极限承载力计算公式和刚度计算公式。基于RPC热工参数值和温度-应力本构关系，建立了钢筋RPC简支梁温度场有限元分析模型和火灾下力学性能分析模型，计算分析了各试验参数对梁温度场分布、承载力和变形的影响规律。项目的研究结论可为RPC结构构件抗火设计方法的提出以及火灾后加固修复建议的提出提供数据参考。项目资助已发表论文4篇，待发表论文1篇。培养硕士研究生5名，其中2名已经取得硕士学位，3名在读。项目投入经费20万元，累计支出16.4万元，各项支出与预算基本相符，项目结余经费3.6万元，用于项目研究后续支出。