【作者】 刘红波；

【导师】 陈志华；

【作者基本信息】 天津大学 ， 结构工程， 2011， 博士

【摘要】 弦支穹顶是一种高效的预应力空间钢结构,已推广用于体育馆、会展中心等近20项大跨度建筑工程中。随着工程应用的推广和研究的深入,在施工控制技术与分析设计理论方面遇到了一些亟待解决的关键课题,包括弦支穹顶结构临时支承结构的分析设计理论、考虑温度变化和滑移摩擦影响的弦支穹顶的预应力施工过程数值模拟与控制理论、太阳辐射作用下弦支穹顶结构温度荷载的数值模拟理论及其温度效应研究等,这些课题解决的好坏,直接影响到弦支穹顶的结构效能、工程造价及施工阶段和使用阶段的安全等问题。本文围绕上述问题,采用数值分析与试验研究相结合的方法,开展了系统深入的分析研究,取得了一些具有科学意义和工程应用价值的研究成果。弦支穹顶施工时通常会采用扣件式钢管满堂支承架作为结构和施工荷载的临时支承,而目前扣件式钢管满堂支承架半刚性分析计算理论尚不完善,由此带来了很多问题,甚至工程事故。结合行业标准《扣件式钢管脚手架安全技术规范》(JGJ 130-2001)修订工作,通过足尺试验和理论分析对扣件式钢管满堂支承架的结构力学特点、分析方法及其设计理论进行了深入的研究,提出了一套完整的扣件式钢管满堂支承架的数值模拟理论和简化计算方法,揭示了各个参数对结构稳定性能的影响规律,相关研究成果已编入行业标准《扣件式钢管脚手架安全技术规范》(JGJ 130-2011)。在弦支穹顶结构预应力张拉施工过程中,环索与撑杆下节点之间的滑移摩擦引起显著的预应力张拉偏差,给结构带来了一定的安全隐患。为系统深入的研究滑移摩擦导致的预应力偏差及其对结构性能的影响,本文基于拉索的热胀冷缩原理及其泛函广义逆的概念,考虑滑移摩擦建立了环索绕撑杆下节点滑移的数值模拟理论,通过ANSYS的APDL语言编程实现;同时基于有限元基础理论,推导了基于有限元列式的三节点滑移索单元和闭合多滑轮滑移索单元的刚度矩阵、质量矩阵,通过商用有限元软件ABAQUS的用户自定义单元功能,将单元算法用于计算机手段进行实现索滑移的数值模拟。通过算例和试验验证上述三种索滑移数值模拟理论的合理性。利用上述理论,分别研究了滑移摩擦导致的预应力偏差的分布规律、偏差对弦支穹顶结构性能的影响、环索滑移与不滑移时结构性能的对比分析等内容,得出了一些可供工程参考的结论。在弦支穹顶结构预应力施工期间,环境温度与结构温度是不断变化的,并且变化的幅度较大,给结构的预应力张拉的精确施工带来技术难题。本文首先通过算例分析得出由预应力张拉期间环境温度变化引起显著的预应力张拉误差,误差可达212%,因此必须考虑环境温度的变化对预应力施工的影响。为考虑施工期间环境温度的变化对预应力施工的影响,本文提出了循环补偿法和简化线性方法来考虑施工过程中环境温度变化对预应力张拉施工的影响,通过算例对方法的合理性和精度进行了验证。在弦支穹顶结构的施工阶段和使用阶段,其结构本身的温度场是一个不断变化的过程。温度作用作为一种特殊的荷载,与重力荷载、风荷载、地震作用等常规荷载有着本质的不同,后者可通过增强结构的刚度来有效抵抗,但是前者却不然,刚度越大,温度作用引起的内力就越大,因此对于温度作用引起的内力不能仅靠增加结构的刚度来抵抗。本文采用有限元理论研究了温度作用对弦支穹顶的预应力大小、节点位移、杆件内力和支座反力的影响,揭示了拉索材料和支座约束刚度对温度作用下弦支穹顶结构性能的影响规律。在弦支穹顶结构的施工阶段和使用阶段,其结构温度场不仅受到环境空气温度的影响,而且还受到太阳辐射的影响,太阳辐射作用下,结构表面的温度可超出环境空气温度20℃之上,若设计和施工过程中不能合理的考虑结构的温度场,将会引起安全隐患。本文基于有限元理论,建立太阳辐射作用下钢结构温度场数值模拟方法,并提出了一种高效的太阳阴影计算方法。采用本文建立的数值模拟和阴影计算方法采用ASHRAE晴空辐射模型,建立了太阳辐射作用下钢结构的温度场分析模型,研究了钢板太阳辐射吸收系数、地面辐射反射系数、构件规格和空间方位对结构温度场的影响,完成了钢板、钢管、箱型钢管和H型钢四组太阳辐射下钢构件的温度场试验,验证了理论分析模型和简化计算方法的有效性和合理性。利用本文提出的太阳辐射下钢结构温度场数值模拟方法,研究了太阳辐射下弦支穹顶和弦支穹顶叠合拱结构的温度场分布规律,并揭示了此温度场下弦支穹顶的结构响应规律。更多还原

【Abstract】 As an efficient pre-stressing spatial structure, the suspen-dome structure has been widely adopted in long-span buildings, such as gymnasiums, exhibition center and so on. Some burning problems have occurred during the researches and application of suspen-dome structures, which will make a significant effect on its cost and its safety. These problems include the design and numerical simulation theory of temporary falsework structures, numerical simulation theory of pre-stressing construction process considering the sliding friction and temperature change, numerical simulation theory of temperature field theory under solar radiation and its temperature effect and so on. Consequently, a systematical study was carried out to solve the above burning problems by theoretical analysis and experimental researches, and some achievements, having obviously scientific and technological significance, were obtained.The structural steel tube and coupler scaffolds (hereinafter referred to as STCS) were usually adopted as the mian falsework during the construction of suspen-dome structures. Many disastrous collapses of STCS’s have occurred due to that no perfect design guidelines are obtained in current research. A systematic research on the structural characteristics, analysis method and design method have been conducted through experiments and finite element analysis and the numerical simulation theory and simplified calculation method of STCS were presented. In addition, the effects of various parameters on the stability of STCS were analyzed. Some achievements presented in this paper were adopted in the industry standard, technical code for safety of steel tubular scaffold with couplers in construction.A remarkable pre-stressing deviation is induced by the sliding friction between hoop cable and cable-strut joint, and this deviation brings hidden danger of suspen-dome structures. In order to research the pre-stress deviation distribution and its effect on the structural behavior, three numerical simulation method for the cable sliding were presented. The first method was presented based on heat expansion and cold contraction and generalized inverse, and this method can consider the sliding friction and can be realized in ANSYS software using APDL language. The second method was to derive the stiffness matrix of three-node cable sliding element based on the finite element theory, and this method can realized in ABAQUS software using its UEL function. The third method was also to derive the stiffness matrix of closed sliding polygonal cable element based on the finite element theory, and this method can realized in ABAQUS software using its UEL function. The above three methods were verified by example analysis and experiment. Using the above three methods, the distribution of pre-stressing deviation and its effect on the structural behavior of suspen-dome were studied as well as the structural behavior of suspen-dome structures with various friction coefficient. Based on those analyses, some meaningful conclusions were obtained in this paper.The temperature of suspen-dome structures and ambient air temperature are changing during construction, and the temperature changes bring technical problems for the pre-stressing construction. The pre-stressing deviation was investigated though example analysis and the analysis results showed that the deviation induced by temperature change during construction is up to 212%. So the temperature change must be considered in the pre-stressing construction. In order to consider the temperature change in pre-stressing construction, a new pre-stressing construction control method and simplified calculation formula, is presented in this paper, which is verified by example.The temperature load of suspen-dome structures is change during the construction and usage stages. Comparing with the common loads, such as gravity, wind load and seismic action, temperature action is quite different. The former loads can be overcome by increase the structural stiffness, but the temperature action cannot. Furthermore, the structural stiffness is lager, the stress and displacement is larger. The influence of temperature load on the pre-stressing value, node displacement, member stress and reaction were studied by finite element analysis.In the process of construction and service stage of suspen-dome, the temperature distribution is affected not only by ambient temperature but also by solar radiation. Considering the effect of solar radiation, the steel temperature may be 20℃higher than the corresponding ambient temperature. Therefore, there will be hidden danger under condition that a non-rational temperature distribution is used in design. In order to provide a rational temperature data for structural design, a numerical simulation model based on ASHRAE model is presented for the temperature field analysis considering the solar radiation, and a solar shadow algorithm was also presented in this paper. A parametric study was carried out in order to investigate the influence of the steel solar radiation absorption, the solar radiation reflectance, steel member size and orientation. Four groups specimens including steel plates, steel tube, steel rectangular tube and H-shaped steels were designed and measured not only to provide insights into temperature distribution of steel members under solar radiation but also to provide data to verify future analytical results and simplified design formula. Using above method, the temperature distribution and temperature effect of suspen-dome structures and suspen-dome with stacked arch were investigated, and some significant conclusions were obtained.更多还原