结构用胶合竹在不同纤维配置情况下的断裂性能研究

Modern bamboo structure has widely application prospect because of its huge advantages in resource conservation and environmental protection. However, stress concentration and crack initiation at defects or hole edges in the bamboo structure often result in a significant decrease in load bearing capacity. To ensure the structure safety, it is essential to study the fracture properties of glued laminated bamboo for determining the bearing capacity reasonably with fracture mechanics. In the present project, glued laminated bamboo with different fiber configurations used in modern bamboo structures are investigated based on the quasi-brittle fracture testing methods and theories for concrete. The initial fracture toughness and the R-curve are determined and applied to describe the fracture characteristics of glued laminated bamboo. And then, the cohesive law and the fracture criterion are studied. Moreover, the failure mode of the glued laminated bamboo and the influence factor of the fracture parameters are analyzed to study the fracture mechanism. The research results will provide guidelines and theoretic supports for the safety assessment and the performance improvement of modern bamboo structures.

现代竹结构因其在节约资源和保护环境方面的巨大优势而具有广阔的应用前景。然而，竹结构缺陷处应力集中明显，构件开孔常引发开裂而导致构件的承载力降低。掌握胶合竹材料的断裂性能，基于断裂力学方法合理确定构件承载力，是确保竹结构安全运行的关键。本项目拟参考混凝土类准脆性材料断裂试验方法及断裂理论，研究确定结构用胶合竹不同纤维配置情况下的起裂韧度和R阻力曲线，并以此作为描述胶合竹断裂特性的特征物理量，建立结构用胶合竹的粘聚本构关系和裂缝扩展准则，探索结构用胶合竹的断裂破坏形式及断裂参数的影响因素，揭示结构用胶合竹的断裂破坏机理。项目的研究成果为竹结构的安全性评估和性能提升设计提供科学依据和理论指导。

为正确测定胶合竹断裂韧度参数以合理确定胶合竹结构的承载能力，研究胶合竹断裂破坏模式及性能并针对胶合竹的薄弱环节寻求增韧方法以提升竹结构性能，申请者开展了单向纤维不同尺寸、不同试件形式胶合竹断裂试验，双向纤维不同配置的胶合竹断裂试验，建立了三点弯曲梁测定单向纤维胶合竹I型断裂韧度的试验方法。研究了断裂呈准脆性特征的胶合竹起裂韧度理论确定方法，双向配置胶合竹以能量释放率表述的R曲线的计算方法，断裂呈准脆性特征的胶合竹粘聚本构的确定方法，建立了胶合竹基于R曲线的韧性评估方法。分析了纤维配置对R曲线的影响及双向配置胶合竹破坏模式，建立了针对胶合竹的薄弱环节的增韧方法。