【作者】 周泉；

【导师】 肖岩；

【作者基本信息】 湖南大学 ， 结构工程， 2013， 博士

【摘要】 在全球能源不断减少和世界节能减排思想的不断蔓延的国际大环境下,土木工程领域中的Glubam胶合竹梁从初步的“以竹代木”构想逐步发展成为涉及桥梁、房屋、大型场馆等各个方面的新型结构构件。在不发达国家的农村和乡镇里,Glubam胶合竹梁沿用了木结构的发展历程,不仅可以用来建造简易住宅和临时建筑,还成功应用到厂房、学校等公共建筑领域。Glubam胶合竹梁是参照胶合木工业技术,应用现代设计理念和工艺技术开发的一种新型承重构件。指接技术的引入使得竹梁的加工不受原材料尺寸的限制,并且使板材的对接更加紧密和牢固。指接胶合竹梁不同于其他形式的竹梁,具有加工简单、形式多样、维护简便等优点。在成功将指接胶合竹梁应用到现代竹结构单体房屋、竹结构活动房、现代竹结构人行桥梁和车行桥梁之后,常规的力学性能研究已经极大的限制了竹梁应用的推广,胶合竹的应力应变关系、指接节点失效模型、桥梁中竹梁的疲劳性能和竹梁弯剪荷载条件下的失效准则都是亟待解决的问题。本文对Glubam胶合竹梁的加工工艺、失效理论研究、基本物理力学性能、力学试验研究、工程应用等方面分别进行了阐述,具体工作如下：1.本文详细介绍了竹木结构的发展历程以及Glubam胶合竹梁的种类划分、加工工艺和工程应用,论述了新型竹材梁的研发现状和使用情况。通过两个典型的工程应用实例,展示了现代竹结构桥梁的构件加工、结构形式和设计方法。通过成桥试验和长期观测,分析了现代竹结构桥梁的安全性和耐久性,并结合相关规范对结构承载力进行验算。简单的成型技术、可观的经济性、良好的安全性以及丰富的原材料为Glubam胶合竹梁在桥梁中的推广和使用奠定了基础,也为改进胶合竹的结构性能研究和开发更优化的结构体系提供了参考。2.从失效准则基本理论出发,论述了各向异性材料的经典准则公式Tsai-Wu的参数和适应范围。结合Glubam胶合竹梁交织状构造和分层结构的特点,推算出Glubam胶合竹梁在平面应力状态下的一般失效公式,将复杂各向异性材料的三向应力问题转化为简单的平面应力问题。通过数值计算方法推导Glubam胶合竹梁在荷载(M,V)下的截面应力公式。对工程使用中四种胶合竹梁的受力情况进行分析,得到各自的极限承载力的计算公式。其中普通胶合竹梁忽略胶合层的不连续性,采用纯材料连续介质计算方法：指接胶合竹梁可将指接层和非指接层分别进行应力分析,然后利用力平衡关系算出中性轴位置,最后得出竹梁承载力。3.参考国内外相关文献,总结了有关胶合竹材的一系列试验成果,简单描述了其力学性能方面的特性及物理力学指标,为胶合竹梁的强度和刚度研究提供了基础的理论依据。参考木结构物理力学试验规范和美国NDS设计规范,引用胶合竹抗压、抗拉、抗弯和抗剪试验、胶合竹徐变试验、螺栓连接方式性能试验以及前人做的竹材干湿度试验,对胶合竹的整体性能进行阐述和分析,并通过回归拟合得到任意湿度条件下竹材的弹性模量计算公式。采用Burger模型对胶合竹梁的蠕变性能进行模拟,通过蠕变试验后的静力破坏试验以及回归拟合,可以得到Glubam胶合竹梁的蠕变变形计算公式。试验证明荷载的长期作用会在一定程度上降低竹梁的承载能力与非线性阶段的刚度。通过考虑含水率、材料变异、徐变、天然缺陷、应力集中等参数影响,对试验结果进行修正后得到Glubam胶合竹梁的容许设计应力。4.通过Glubam胶合竹梁静载试验,对比不同连接方式、叠合方式、FRP增强措施对竹梁承载力和刚度的影响,并基于几点基本假设,建立了竹胶合梁强度和挠度等计算公式。引入Glubam胶合竹梁的相关试验数据与计算结果进行对比,可以发现Glubam胶合竹梁的计算模型能够很好的估计构件的承载能力,为工程应用提供可靠的计算依据。在已建成的现代竹结构车行桥梁同批次产品中,随机抽取一组胶合竹梁试件进行试验。将200万次反复荷载试验后的试验组试件与对比组试件的试验结果进行对比后发现,胶合竹梁抗疲劳性能良好,能够满足桥梁设计的50年使用期限的基本要求。试验组试件的疲劳荷载在不超过设计荷载的条件下,试件刚度无明显下降。通过静载破坏试验的结果对比,发现疲劳试验对试件的极限强度有少许削弱。疲劳试验对Glubam胶合竹梁的刚度和强度的影响在锤击法激励的模态试验中得到了进一步的验证。本文通过对Glubam胶合竹梁进行一系列的试验研究后发现：Glubam胶合竹梁具有良好的抗弯能力和疲劳性能；其抗弯试验结果能够很好地验证其承载力计算公式,为竹结构桥梁的荷载计算提供重要依据；对Glubam胶合竹梁的试验分析和理论研究为胶合竹的推广和应用提供了可靠的学术参考,也为相关规范的编制和工程应用提供了依据。更多还原

【Abstract】 Sustainability becomes the major concern of today’s society. Glubam (glue laminated bamboo) has emerged in such background, derived from the primary idea-"replace wood using bamboo’". Now glubam is related to all the aspects of construction including bridges, buildings, pavilions. It has a wide application, not only used for simple houses and temporary buildings in underdeveloped rural areas, but also applied for public buildings such as factories and schools.Based on the modern design concept, innovative construction technology and some industrial technologies for the wood, finger-joint Glubam beam has many advantages compared with other types of bamboo beams. For instance, it is easy to construct and to maintain, and it can have many different types. Finger-joint technology solves the dimension limitation of Glubam beam due to material. It has successfully been applied to the modern bamboo single house, bamboo prefabricated building, modern bamboo pedestrian bridge and modern bamboo vehicle Bridge. Since conventional knowledge for wood is not fully applicable to Glubam beam, deeper study such as stress strain relationship, node failure model, fatigue property for the bamboo beam in bridge and failure criterion of the bamboo beam under combination of bending and shear become the key topic for discussion. The basic physical and mechanical properties of the laminated bamboo, processing technology, engineering application, mechanics testing, failure theory of gluing bamboo beams are described in this thesis as follows.1. This thesis detailedly introduces the types division, processing technology and engineering application of Glubam beam. Depending on two typical examples of engineering application, a comprehensive display of component processing, bridge skeletion and design method is showed. Systematic safety analysis of the modern bamboo structure and durability of the bridges are verified by bridge test and long term observation. Then, the structure bearing capacity is carefully checked subject to the relevant codes. The Glubam bridge provides a substantial foundation for the application of Glubam beam with its advantages of simple molding technology, considerable economic performance, good safety and abundant raw materials.2. The section stress formula of Glubam beam under load (M. V) are described in the last chapter. Firstly, the situation of Glubam under bending moment and shear force is simplified; secondly, the formulas of stress distribution are displayed for pure bending and pure shear loading conditions. During the derivation, cross sectional conversion and equivalent method are employed to solve the shear stress distribution in finger-joint and the ultimate load of FRP beams. Based on the classical criterion formula Tsai-Wu failure criterion, the Glubam gluing bamboo is simplified as orthotropic materials and the general failure formula for Glubam beams under bending and shear loading is put forward. The feasible calculation model of FRP reinforced Glubam beam which bases on general structure network analysis is found3. This thesis briefly described the mechanical properties of Glubam which depend on the test results in related literature. Deriving from small clean specimen experiments, bolt connection tests and humidity tests, the overall performance of glue laminated bamboo were described and analyzed. What’s more, the regression formulas under any humidity condition are also listed, and creep calculation formula of Glubam is obtained subject to the Burger model in48th literature. Comparing the test results, it can be seen that the creep action weaken the bearing capacity and nonlinear stiffness of Glubam beam.4. Undering some basic assumptions, the strength and deflection calculation formula of Glubam beam are established through static tests, and the calculated results match experimental results well. It can be seen from the test results that the vertical bolt reinforcement measures in a certain extent reinforced the stiffness and strength of Glubam beam, while the FRP measures increased the bearing capacity of bamboo beam and the damage often occurred in compression area. Randomly selecting two group of specimens in the same batches of products which were used in vehicle bridge for the fatigue tests, it is obtained that the fatigue resistance performance of gluing bamboo beam is so good that contents the basic design requirement for50years servation. When the fatigue loads do not surpass the design value, the rigidity of test specimens does not descrease. Depend on the static test results-it is found that the fatigue tests slightly weaken the ultimate strength of the specimens. Hammer method of modal test has been further verified the fatigue effect on the stiffness and intensity of Glubam ejuine bamboo beam.To sum up.(?) is obvious that the Giubam beam has many advantages such as eminent mechanical properties, innovative design method of Glubam beam progress, economical and practical value. The experimental research and theoretical analysis of Glubam beam provide a reliable academic reference for promotion and application of bamboo, but also a data set for establishing and updating design codes and guidelines for future engineering applications.更多还原