【作者】 龙激波；

【导师】 李念平；

【作者基本信息】 湖南大学 ， 供热、供燃气、通风及空调工程， 2013， 博士

【摘要】 随着世界人口增加和建筑业的发展，建筑业能源与材料的需求也日益增大，建筑业对自然环境的直接或间接破坏已成为人类对自然环境的损害的重要因素。竹材作为一种新型建筑材料，在一些建筑结构中逐渐成为混凝土、砖、钢材等传统建筑材料的替代材料。根据多孔介质的定义及其结构具有的固体骨架和孔隙空隙特点，建筑中使用的竹材属于典型的多孔介质材料。当环境温、湿度变化时，竹材结构内热湿传递使结构产生热胀冷缩变形和湿胀干缩变形，当这种变形受到约束在结构内产生热湿应力。影响竹材结构热湿应力的温度与湿度虽然在竹材内传递的作用机理不同，但对竹材结构的伸缩变化具有相同的结果。因此，对竹材结构的热湿应力问题展开研究，开发和应用新型竹材，减少以及防止热湿应力对建筑的破坏是当今建筑节能中的一项重要工作。然而，在建筑结构热、湿应力的研究中，通常分析热应力的影响，对热湿耦合作用下的热湿应力的研究较少，没有考虑温度场与湿度场对热应力与湿应力的相互影响。由于缺乏多孔介质材料的湿胀干缩性能参数，特别是材料的湿膨胀系数，工程设计中还缺乏相应的设计标准和可靠的参考数据。因此，本文从竹材的多孔介质特性、竹材结构内的热湿耦合传输入手，以竹集成板、竹篾胶合板、竹筋混凝土复合结构等为主要研究对象，揭示热湿环境下温度、湿度、材料热湿膨胀特性对竹材的热工特性和热湿应力变化规律，为竹材等多孔介质结构的进一步应用研究提供基础。本文的研究工作和成果主要包括：(1)详细介绍了竹材的多孔介质特点、竹材结构内部的热、湿变化原因和热、湿传递机理，重点阐述了竹材在热湿耦合作用下的热湿变形机理与热湿应力特性，提出了多孔介质湿应力基本概念，介绍了多孔介质湿应力的数学微分方程及其物理意义，为后续章节的热湿应力分析阐明了理论基础。(2)通过对多孔介质宏观结构的假设，以单位长度微元体为对象，分析了多孔介质结构热湿传递中的热湿弹性行为，阐明了竹材结构热湿应变与应力的分析方法，建立了热湿应力的数学模型，进一步以竹材结构墙体为研究对象，分析了墙体热湿应变与热湿应力的变化特性。阐明了竹材结构墙体热湿应力变化的影响因素，指出温度与含湿量变化是影响热湿应力变化的最重要因素。(3)阐述了影响竹材结构热湿应力的孔隙率、有效导热系数、热湿膨胀系数等基本物理力学性能参数。采用吸渗法测试了建筑竹材的有效孔隙率，指出常温下竹材试件的有效孔隙率为32.1%~33.7%。提出了竹材湿膨胀系数的概念，采用电阻应变法测试了建筑竹材的热膨胀系数和湿膨胀系数，指出竹材试件的热膨胀系数为纵向9.67×10-6℃-1、横向22.30×10-6℃-1，湿膨胀系数为横向55.28×10-6m/(m·%)、纵向11.64×10-6m/(m·%)，横向热膨胀系数为纵向的2.31倍，横向湿膨胀系数为纵向的4.75倍。分析了竹材含湿量变化对有效导热系数、有效比热容、温度波延时系数等竹材结构墙体热工性能参数的影响，进一步分析了含湿总量变化与墙体总热阻的关系，为竹材结构热湿应力分析提供了基本的物理力学性能数据。同时，采用电阻应变法测试竹材湿膨胀系数，为多孔介质材料湿膨胀系数的测试方法提供了参考。(4)分析了一维稳态热湿传递工况下竹材结构墙体的热湿应变变化特性，阐明了伸缩热湿应力与弯曲热湿应力的计算方法。建立了墙体稳态热湿应变与应力的微分方程，指出墙体产生的热湿应力为其自由膨胀计算值与测试值之差。以竹篾胶合板材墙体为研究对象分别对墙体的热应变特性、湿应变特性、热湿应变特性进行了实验研究，分析了墙体温度变化和含湿量变化时热湿应力的变化规律，指出墙体内热应变与湿应变具有叠加的作用效果，为新型竹材结构的稳态热湿应力设计提供设计依据。(5)分析了一维瞬态热湿传递工况下竹材结构墙体的伸缩热湿应力与弯曲热湿应力变化特性，建立了热湿应力与墙体厚度方向温湿度梯度关系的微分方程和热湿应力随时间变化关系的微分方程，阐述了影响竹材结构墙体瞬态热湿应力的影响因素，指出墙体内温度、湿度、温度梯度、湿度梯度是影响其热湿应力变化的主要原因。以竹集成板材为研究对象，分别在加热升温、高温墙体快速加湿、高含湿量墙体快速加热等典型瞬态热湿工况下对墙体的热湿应变进行了实验研究。以竹篾胶合板材为研究对象，在自然热湿环境下对墙体的热湿应变进行了连续实验测试与研究，分析了瞬态工况下墙体的热湿应力变化规律。研究结果表明瞬态热湿工况下墙体的热湿应力变化是一个复杂和多变的变化过程，对新型竹材结构的瞬态热湿应力利用或防止应力发生具有指导意义。(6)分析了竹筋与混凝土界面的热湿应力变化特性，阐明了竹筋混凝土复合结构中两种材料界面接触力、界面正向应力、界面切应力、轴向正应力等应力的计算方法。对常温下水泥砂浆的湿膨胀特性进行了实验测试，指出水泥砂浆的湿膨胀系数与含湿量基本呈线性关系变化。进一步以单根竹筋的圆柱形竹筋混凝土构件为研究对象，分析了竹筋混凝土温湿度变化时对界面热湿应力、轴向热湿应力变化的影响，阐述了竹筋混凝土结构失效的重要原因，为竹筋混凝土复合结构的设计与应用管理提供了参考。更多还原

【Abstract】 With the increase of population and development of construction industry, thedemand of energy and material in construction industry is bigger and bigger. Thedirect and indirect destroying to the natural environment from construction industry isan important reason why the natural environment is destroyed by people. Bamboowood is a kind of new building material. Bamboo wood is gradually becoming thesubstitute material of the traditional building material (concrete, brick, steels, etc.) inbuilding structure. According to the definition of porous media, bamboo wood belongsto typical porous material because of the solid skeleton and pore space that thebamboo wood has. When the environmental temperature and humidity change, theheat and moisture transfer in bamboo wood structure produces the distortion ofexpanding with heat and contracting with cold and expanding with moisture andcontracting with dry. If the distortion is constrained, thermal and moisture stress isproduced in the structure. Though the work mechanism of the transfer of thetemperature and humidity that influence the thermal and moisture stress in the bamboowood structure building is different, they have the same effects on the expanding andcontracting of bamboo wood structure. So, it is an important work in current buildingenergy-saving work to do research on the thermal and moisture stress in bamboo woodstrcuture and to develop and apply this kind of new bamboo structure and reduce andavoid destroying buildings from thermal and moisture stress. On the earlier study ofthermal and moisture stress in building structure, the effect of thermal stress isanalyzed, but the thermal and moisture stress is less studied under coupling effect ofheat and moisture. Interaction effects to thermal and moisture stress from temperatureand humidity fields are not taken into consideration. Due to the lack of theperformance parameters with expanding with moisture and contacting with dry ofporous media, especially the hydroscopic expansion coefficient, there is noappropriate design standard and reliable data in engineering design. This paper startswith properties of porous media in bamboo wood and coupled thermal and moisturetransfer in bamboo structure building. Bamboo plywood wall and bamboo reinforcedconcrete composite structure etc. are the research subjects. The change rules ofthermal and moisture stress influenced by temperature, humidity and expandingproperties of the porous media are revealed in bamboo structure buildings in hot and humid conditions. This provides the basis for further study of porous media likebamboo wood. The study content and result of the paper include:(1) In the paper, the characteristics of porous medium of bamboo structure, thereason of heat and moisture change and the transfer mechanism of heat and moistureare introduced in detail. It emphasis on the deformation mechanism and stresscharacteristic of heat and moisture of bamboo structure under the heat and moisturecoupling transfer. The concept of wet of porous medium is proposed, and itsmathematical differential equation and physical significance are introduced whichprovides the theoretical basis for heat and moisture stress analysis in subsequentchapters.(2) The heat and moisture elastic behavior of porous medium structure in heatand moisture transfer is analyzed through assuming the macrostructure of porousmedium and using micro-element volume per unit length as an object. The analyticalmethod and mathematical model of heat and moisture stress and strain of bamboostructure building are expounded. And furthermore, using the wall of bamboostructure as an object, the variation characteristic of the stress and strain of heat andmoisture is analyzed, and the impact factors on change of heat and moisture stress ofthe wall with bamboo structure are presented, which indicates that the temperature andmoisture content change are the most important factors.(3) The basic physical and mechanical performance parameters such as porosity,effective thermal conductivity coefficient, thermal and humidity expansion coefficientwhich influence the thermal and humidity stress of bamboo structure building areclarified. The effective porosity of building bamboo is tested by absorption osmoticmethod, which points out that the effective porosity of bamboo test specimen is32.1%~33.7%in normal temperature. The concept of humidity expansion coefficientis proposed. And the thermal and humidity expansion coefficient of building bambooare tested by strain method, the results indicate that the thermal expansion coefficientof bamboo test specimen is9.67×10-6℃-1in vertical and22.30×10-6℃-1in transverse,the humidity expansion coefficient is55.28×10-6m/(m·%) in transverse and11.64×10-6m/(m·%) in vertical, the thermal and humidity expansion coefficient intransverse is2.31and4.75times that of the vertical, respectively. The influence ofmoisture content change on thermal performance parameters such as effective thermalconductivity, effective heat capacity, latency coefficient of temperature wave areanalyzed. And furthermore, the correlativity between the total moisture content andthe total thermal resistance of wall is obtained, which demonstrates the basic data of dynamics in physics for analysis of thermal and moisture stress in bamboo woodstructure buildings. At the same time, strain method is adopted to test the moistureexpansion coefficient of bamboo wood. This provides reference for the test methods ofmoisture expansion coefficient for porous medium materials.(4) The change characteristic of thermal and humidity strain of bamboostructure wall under one-dimension steady-state heat and moisture transfer conditionis analyzed and the calculation method of stretching and bending thermal andhumidity stress are expounded, and the differential equation of steady-state thermaland humidity strain and stress of wall is established，which indicates that the thermaland humid stress produced by wall is the D-value of the free expansion calculatedvalue and the test value. And then the characteristic of thermal strain, humidity strainand thermal-humidity strain of wall are studied respectively by using bamboo stripagglutination plank wall as an object. The change rules of thermal and moisture stresswhen the temperature and humidity content of the wall change are analyzed. It pointsout that the thermal strain and the humid strain produce superimposed effect. Thisprovides design basis for steady-state thermal and moisture stress design ofnew-model bamboo wood structure buildings.(5) The change characteristic of stretching and bending thermal and humiditystress of bamboo structure wall is analyzed under one-dimension steady-state heat andmoisture transfer condition, the differential equation of temperature-humidity gradientbetween thermal-humidity stress and wall thickness direction and differentialequation of thermal and humidity stress with time changes are established. The mainfactors of influencing the transient thermal and humidity stress of bamboo structurewall are temperature, humidity, temperature and humidity gradient. Using integratedplank of bamboo as an object, the thermal and humidity strain of wall in typicaltransient thermal and humidity condition including heating, rapidly humidifying onhigh temperature wall, rapidly heating on high moisture wall are studied withexperimental. Meanwhile, using bamboo strip agglutination plank as an object, thestudy on the thermal and humidity strain under natural thermal and humidityenvironment are done continuously with experimental test method. The change rulesof thermal and moisture stress in wall under transient condition are anayzed. Theresults show that thermal and humidity stress change under transient thermal andhumidity condition is a complex and changeful process. This gives guidance for theutilization of transient thermal and moisture stress or the prevention of stressoccurrence in new-model bamboo wood structure buildings. (6) The change characteristic of thermal and humidity stress of bambooreinforcement and concrete interface is analyzed, and the calculation method ofcontact force, normal stress, shear stress of interface and axial normal stress areclarified in bamboo reinforce concrete composite structure. the experimental test onhygral expansion characteristic of cement mortar under normal temperature provesthat the hygral expansion coefficient and moisture content of cement mortar arelinearly correlated, and further, the influence of thermal and humidity stress change onthe thermal and humidity stress of interface and axial is studied by using cylindricalbamboo reinforce concrete component of single bamboo reinforcement as an object,the significant reason why bamboo reinforce concrete structure become invalid isobtained. This sheds light on the design and application administration of bambooreinforce concrete composite structure.更多还原