火灾下复合材料夹芯构件多尺度性能演化机理及安全评估研究

The structural sandwich components have been widely used in civil engineering, transportation and offshore engineering due to its advantages of light weight, high strength and anti-corrosion ability. However, unlike the RC and steel components, the coupling effects of physical - chemical – mechanism, generated from fire disaster, would seriously endanger the safety of sandwich components.. The multi scale performance analysis and safety evaluation of structural sandwich components will be studied in this program, involving (1) the thermal decomposition of face sheets and core will be investigated at a micro level, and the heat conduction mechanism of components will be investigated at a meso level. The thermodynamics model considered the coupling effects of physical -chemical - mechanism can be established; (2) combining the material and interface failure at a micro level and structural failure at a macro level, the multi scale failure mechanism of components can be summarized via multi-point constraints method;(3）under the consideration of physical -chemical - mechanism coupling effects, the fire performance evolution model of sandwich components can be developed; and (4) The safety evaluation based on time一variant reliability analysis will be conducted, which also can be used to evaluate the existing components with fire protection. The implement of this program builds theoretical basis for component fire design and safety evaluation.

复合材料夹芯构件凭其轻质、高强、耐腐蚀等优点在土木、交通、海洋领域广泛应用。然而与传统结构件不同，火灾下复合材料夹芯构件处于物理—化学—力学耦合作用状态，从而导致构件抗火分析趋于复杂。本项目系统研究火灾下复合材料夹芯构件多尺度性能演化机理及安全评估方法。主要包括：（1）从微观尺度研究纤维增强复合材料及芯材热分解机理，从细观尺度研究组分材料及材料间热传导机理，建立物理-化学-力学耦合作用下材料热力学分析模型；（2）将细观材料失效、界面失效与宏观构件失效机理相结合，通过多点约束法进行跨尺度关联，建立多尺度构件失效模型；（3）将材料热力学性能、热传导模型与弹塑性理论相结合，建立构件火灾全过程性能演化模型；（4）将材料热力学性能与时变可靠性分析相结合，建立基于受火时间的构件火灾安全评估方法，且该方法可应用于有防火保护措施的构件。本项目的实施,为复合材料夹芯构件的抗火设计及安全评估奠定理论基础。

本项研究通过对复合材料夹芯构件火灾作用下热力学演化机理和火灾全过程性能的试验、数值及理论研究，获得主要成果总结如下：（1）测定了纤维增强复合材料面层及芯材热分解反应参数，基于化学反应速率，建立了考虑受火时间的纤维增强复合材料面层及芯材热分解计算模型和瞬态热传导模型，得到了组分材料物理—化学—力学耦合作用下的热力学响应；（2）从细观尺度的材料性能演化及界面力学性能退化到宏观层次的构件破坏模式多尺度揭示了复合材料夹芯构件火灾失效机理，建立了多尺度、递进式构件火灾失效分析方法；（3）确定了复合材料夹芯构件火灾全过程性能，综合考虑物理—化学—力学耦合作用，建立了基于受火时间的复合材料夹芯构件火灾全过程性能演化分析模型；（4）建立了基于受火时间复合材料夹芯构件火灾安全评估方法，可用于指导复合材料夹芯构件在应用中遇到的结构受火问题。