考虑初弯曲影响的FRP型材轴心受压构件屈曲失效机理与稳定计算方法研究

The primary objectives of this research are to investigate the buckling mechanism and calculation method of stability of concentrically loaded pultruded fiber-reinforced polymer (FRP) members with initial out-of-straightness. Firstly, the buckling failure mechanism of different failure modes of pultruded FRP profiles is revealed, and the influence of different form of initial crookedness on the failure modes of pultruded FRP members is studied. Meanwhile, the quantitative index distinguishing different failure modes of concentrically loaded pultruded FRP members with initial out-of-straightness is proposed through experimental and numerical investigations. Subsequently, the influence law of corresponding parameters (including initial crookedness) on the performance of stability of pultruded FRP elements is stated, and the unified calculation model for different failure modes of pultruded FRP profiles with initial out-of-straightness is developed and validated based on the results from experiments, test database and numerical simulations. Finally, the evaluation index and assessment method of stability performance of axially loaded pultruded FRP structural members with initial crookedness are proposed, and further, the stability design method of pultruded FRP structural struts with initial out-of-straightness is developed and validated through structural experiments. This research will contribute to the promotion and application of pultruded FRP profiles in civil engineering and provide the paramount reference for the subsequent code of FRP structures.

针对目前FRP型材轴压构件研究中存在的主要问题，本项目考虑了FRP构件的初弯曲对其稳定性能的影响，重点对FRP型材轴心受压构件的屈曲破坏机理及其稳定计算方法进行深入研究，具体为：首先，通过系统的FRP轴压构件试验并辅以数值模拟，揭示不同失效模式下FRP轴压构件的屈曲破坏机理，及不同的初弯曲形式对FRP轴压构件屈曲破坏模式的影响，并提出考虑初弯曲影响的区分FRP轴压构件不同屈曲失效模式的定量指标。然后，基于试验结果及数据库并结合数值计算，阐明包含初弯曲在内的相关参数对FRP轴压构件稳定性能的影响规律，建立考虑初弯曲影响的FRP轴压构件屈曲临界力的统一计算模型。最后，提出FRP轴压构件稳定性能的评价指标和评价方法，建立FRP轴压构件的稳定设计方法，并通过结构试验检验其可靠性。本项目的研究将促进FRP型材在土木工程领域进一步推广应用，同时也为未来的FRP结构规范提供了重要参考。

本项目系统开展了考虑初弯曲影响的FRP型材轴心受压构件屈曲失效机理与稳定计算方法研究，取得了创新成果。通过材性试验，考察了不同类型FRP型材（不同纤维及树脂种类）的基本力学性能。通过实际测量FRP构件的初始弯曲以及收集整理文献中的相关数据，给出了FRP构件初始弯曲与通用长细比的关系。以此为基础，根据所建立的数据库，给出了考虑初始弯曲影响的FRP型材的稳定系数表达式，使得欧洲规范EC3中的用于钢构件整体屈曲的计算式可用于FRP轴压构件整体屈曲临界力的预测；同时，也给出了精度更高的考虑初弯曲影响的拟合公式，并通过与既有的五种计算方法对比，证明了上述两种计算方法具有较好的预测性能及精度。基于节点试验，建立考虑节点滑移效应的格构式结构的计算模型，并通过结构试验数据以及与既有计算模型的对比，证明了所提出的计算模型的预测性能及精度。最后，通过一个全FRP桁架梁-格构柱结构的实际工程，验证了上述成果的实际应用的能力与前景。