活性粉末混凝土高温爆裂规律与抗火设计方法研究

The compressive strength of reactive powder concrete (RPC) is up to 120 ~ 800MPa. RPC is believed to be more susceptible to spalling because of its high density in microstructure. Further, temperature-load paths have significant effect on fire resistance performance of RPC columns. To overcome some of the current limitations, the following studies should be conducted: (1) Investigate the influence of RPC strength, stress levels and permeability on the critical temperature of fire-induced spalling in RPC. The calculation formula of critical temperature of fire-induced spalling in RPC could be obtained. (2) Investigate the influence of the PP fiber and steel fiber contents on fire-induced spalling in RPC with different size, different strength and different stress levels. The calculation formula of fiber content to prevent explosive spalling can be obtained. (3) Based on the pore pressure theory, using Darcy's Law in the RPC hydrothermal model considering the influence of permeability and fiber contents, the numerical model to predict fire-induced spalling in RPC could be presented. (4) Investigate the influence of stress levels and constant temperature time on creep and transient thermal strain of RPC, the formula of creep and transient thermal strain of RPC could be proposed. Then, the temperature-stress constitutive relations of RPC could be obtained. (5) Research the influence of temperature-load paths to the fire resistance performance of RPC column, and its fire safety design method could be proposed.

活性粉末混凝土（RPC）抗压强度高达120~800MPa，微观结构致密，具有受火爆裂易发性，温度-荷载路径对RPC柱高温性能影响显著。针对上述问题，开展如下工作：（1）考察RPC强度、应力水平、渗透性等关键参数对爆裂临界温度的影响，建立RPC爆裂临界温度计算公式。（2）考察聚丙烯（PP）纤维和钢纤维掺量对不同尺寸、不同强度、不同应力水平RPC高温爆裂的影响，建立防爆裂用纤维掺量计算公式。（3）基于孔隙压力理论，考虑RPC渗透性、纤维种类及掺量的影响，将Darcy定律引入数值模型，分析高温下RPC的孔隙压力，提出预测RPC高温爆裂的数值方法。（4）考察应力水平、恒温时间等关键因素对可有效避免爆裂的RPC热徐变、瞬态热应变的影响，建立RPC瞬态热应变、热徐变的计算公式，提出RPC温度-应力耦合本构关系。（5）揭示温度-荷载路径对RPC柱高温性能的影响规律，提出抗火设计方法。

1、结合超细粒致密理论与纤维增强技术，通过优化高温养护工艺，揭示了高温养护提升RPC抗压强度的机理，提出了RPC抗压强度与养护温度和养护时间的量化表达，研发了抗压强度达250MPa的RPC，其强重比为普通钢材的3倍。.2、由于RPC微观结构致密，渗透性低，爆裂临界温度低（约250-300℃），超过爆裂临界温度后爆裂概率高，严重威胁其火灾安全。为揭示RPC高温爆裂规律，基于理想气体状态方程和达西定律，推导了二维孔隙压力方程，开发了火灾下RPC孔隙压力和爆裂模拟软件。揭示了火灾下RPC构件内部孔隙压力、水蒸气和液态水分布规律，通过孔隙压力判别RPC构件高温爆裂，为判别RPC高温爆裂提供技术依据。提出了用爆裂量化火灾后混凝土（C20-C200）表面温度的方法。.3、为避免RPC高温爆裂，提出了采用掺PP纤维增大RPC渗透性、厚涂型防火涂料降低表面温度的防爆裂方法，开展了RPC结构构件抗火性能试验，验证了该方法的有效性。.4、为揭示RPC结构构件火灾灾变规律，提出了RPC高温徐变和瞬态热应变的数学表达，发现RPC受火3h高温徐变可达常温下年徐变的10倍。建立了RPC热力耦合本构关系，量化了瞬态热应变对RPC结构构件耐火极限的不利影响，提出了该类构件耐火极限实用方法，解决了耐火设计偏于不安全的问题。发现了常温下适筋梁在火灾下易发生少筋破坏，基于纤维梁单元模型，提出了避免火灾下RPC梁破坏的最小配筋率计算公式。.5、结合项目研究，发表论文26篇，其中，SCI论文17篇，JCR1区论文10篇，EI论文7篇，在科学出版社出版专著《活性粉末混凝土高温与动态性能》。授权发明专利2项，软件著作权2项，培养博士生5名，培养硕士12名。