横向拉杆约束薄壁型钢管/胶合竹板组合长柱抗压性能与计算方法研究

Researches and applications of bamboo composite elements for engineering structures exploit a new application of bamboo, but gluing failure is a key factor that restricts security application of bamboo composite elements and taking full advantage of bamboo strength. In this research, the specimens with large slenderness ratio for thin-walled steel-tube/plywood bamboo composite hollow column with transverse binding-bars (SBCCB) will be used to deeply study the compressive performance. The compression tests with short term loading will be conducted, and the interface element to simulate the rheological gluing failure of adhesive layers and the finite element model to simulate tests will be established. The damage performance and influence mechanism of SBCCBs under compression will be extensively studied, a quantitative relationship between binding-bars and crack resistance performance will be detailedly studied and design optimization for binding-bars will be carried out. Based on the compression tests with long term loading and finite element simulation for creep behavior, compression stability and creep behavior, and their influence mechanism of SBCCBs will be studied, a quantitative relationship between thin-walled steel-tube and compression stability will be detailedly studied, and design optimization for thin-walled steel-tube will be conducted. The creep behavior and stress relaxation of SBCCBs will be represented by the rheological mechanics method, and the compressive failure mechanism and critical factors will be revealed. The calculation models for ultimate load and ultimate deformation of compression stability will be established, and a practical calculation method for compressive bearing capacity under short term and long term loading will be proposed. This project aims to lay an experiment and theoretical foundation for engineering application and performance research of SBCCBs.

竹材复合结构构件的研发开辟了竹材资源应用的新途径，开胶破坏是制约其安全应用、充分发挥竹材强度的重要因素。本项目以横向拉杆约束薄壁型钢管/胶合竹板组合空芯柱(SBCCB)的较大长细比试件为对象，深化研究SBCCB的抗压性能。拟进行短期荷载抗压试验，构建模拟具有流变特点的胶层开裂的接触单元和试验仿真有限元模型，研究SBCCB的破坏性能与影响机理，重点研究约束拉杆与抗裂性能的定量关系，优化拉杆设计；通过长期荷载抗压试验以及考虑蠕变行为的有限元模拟，研究SBCCB长柱的抗压稳定性、蠕变行为及其影响规律，重点研究钢管与稳定性的定量关系，优化钢管设计；采用流变力学方法表征SBCCB的蠕变和应力松弛行为，揭示SBCCB长柱抗压失效的关键因素和影响机理，建立抗压稳定极限荷载与极限变形的计算模型，提出短期和长期荷载抗压的承载力实用计算方法。研究成果为SBCCB的性能研究和工程应用提供试验和理论依据。

竹材复合结构构件的研发开辟了竹材资源应用的新途径，开胶破坏是制约其安全应用、充分发挥竹材强度的重要因素。本项目以横向拉杆约束薄壁型钢管/胶合竹板组合空芯柱(SBCCB)的较大长细比试件为对象，深化研究了SBCCB的抗压性能与计算方法。对SBCCB进行了轴心抗压试验，考察了SBCCB受压破坏形态，分析了SBCCB的截面尺寸、长细比和截面组合方式对其开胶载荷和极限承载载荷的影响，并将SBCCB的极限压应力与已有的SBCC数据进行了比较；通过非线性回归分析，建立了SBCCB轴心抗压承载力计算公式。结果表明：SBCCB的轴心抗压失效破坏主要为柱端及柱身横向约束拉杆之间的竹胶合板开胶失效和材料破坏失效，其极限承载力不仅与截面尺寸和长细比相关，而且受截面组合方式影响。设置横向约束拉杆可有效减缓开胶失效，改变极限破坏模式，显著提高极限承载力；与SBCC的极限压应力相比，SBCCB的极限压应力平均提高26%。对SBCCB试件进行轴压蠕变试验以及蠕变后二次轴压破坏试验，考察试件的轴压蠕变特点、蠕变后受压破坏形态，并分析长期承载对SBCCB试件轴压极限承载力的影响。结果表明：SBCCB试件的轴压蠕变应变随试件长细比的增大而减小、随轴压应力水平增加而增加；不同长细比试件的蠕变应变－时间曲线均包含瞬态蠕变阶段和稳态蠕变阶段，温湿度变化对其局部蠕变有影响；蠕变对试件的轴压承载力、轴向及侧向变形能力有较大影响；基于流变力学理论的Burgers计算模型可较好地预测SBCCB试件的蠕变应变发展。研究成果为SBCCB的性能研究和工程应用提供试验和理论依据。