大跨度双螺旋单层网壳施工分析优化及温度效应研究

发布时间：2018-02-14 07:49

  本文关键词： 分步建模法 节点半刚性 门式脚手架 遗传算法 焊接残余应力 本征虚拟激励法 膜结构 太阳辐射　出处：《天津大学》2016年博士论文　论文类型：学位论文

【摘要】：随着经济的发展,建筑结构工程的规模进一步扩大、复杂程度进一步提高,建成了一批体型复杂的大跨钢结构。这些大跨空间结构的几何位形、材料力学性能以及边界等条件等在施工过程中往往存在剧烈的变化,竣工时由荷载引起的结构内力和变形均是由各施工步效应依次累积而成,竣工时各个构件的内力分布和变形与实际的施工过程密切相关。同时施工过程往往是建筑结构生命周期中最危险的阶段,据国家有关部门的不完全统计,在我国有大约2/3以上的工程结构倒塌事故发生在施工期间,原因是未考虑结构施工过程中的复杂性。由于涉及方面广,施工力学的理论研究在很多方面还很不成熟,例如施工过程的数值模拟理论、脚手架承载力计算理论、施工过程优化理论、焊接对结构力学性能的影响、施工过程风振响应分析理论等。此外,太阳辐射引起的不均匀温度场对结构施工及服役期间力学性能的影响也是亟待解决的关键问题。单元生死法是目前大跨空间结构普遍采用的施工模拟方法,其原理是将未安装构件的刚度矩阵乘以一个足够小的因子,将未安装构件对结构的贡献减小,以至于可以忽略。但由于采用单元生死法时,被杀死的构件并未真的从结构中删除,这些单元会以“死单元”与“活单元”的公共节点为边界而产生位移,也就是所谓的“漂移”。为克服这一弊端,本文在分步建模法概念的基础上,通过对通用有限元软件进行二次开发,提出了可避免死单元“漂移”的施工模拟方法。同时,以实际工程于家堡交通枢纽的施工过程为背景,对整个施工过程进行了施工模拟,系统研究了提升区在提升过程中的构件应力变化趋势,并对其进行了现场监测。在提出的施工模拟理论的基础上,本文对门式脚手架的极限承载力进行了研究。大跨空间结构施工过程中使用的门式脚手架节点具有复杂的受力性能。不同模块之间的连接节点具有明显的半刚性特征。本文提出了能够考虑节点半刚性的高效数值模拟算法,并同时考虑了构件弯曲缺陷的影响。在此基础上对门式脚手架体系的极限承载力进行了研究。由于大型复杂结构施工的复杂性,施工过程中往往需要数十个支撑胎架。对于具有复杂体型的空间结构来说,比如于家堡交通枢纽,支撑点的选择非常复杂,如何选择最优的支撑点组合对于工程技术人员来说是一个很大的难题,除此之外,最优卸载顺序的确定,整体提升施工提升点的选择等对于施工的安全性至关重要。因此本文基于实数编码遗传算法对上述一系列问题进行了优化。此外,本文结合于家堡交通枢纽的特殊性,利用二进制编码遗传算法对支座刚度进行了优化。目前施工过程中,普遍存在大量的焊接工作。本文结合于家堡交通枢纽这一全焊接结构为工程背景,系统研究了焊接残余应力对厚钢板、箱型构件、以及十字隔板焊接节点力学性能的影响。提出了将焊接残余应力植入整体结构的高效计算方法,大大节省了计算时间,使得在整体结构中考虑焊接残余应力成为一种可能。此外,本文还提出了通过改变材料力学属性来考虑焊接残余应力的方法,并对实际工程进行了分析研究。基于随机振动的频域分析理论,将本征正交分解法与虚拟激励法结合,提出了适用于空间结构的本征虚拟激励法,大大的减小了计算代价。并将该方法用于对整体提升结构的风振响应进行分析,结果表明该方法对于基频较低的柔性结构具有很高的计算效率和精度。大跨空间结构的施工周期一般很长,因此施工过程中的结构不仅要承受日气温变化,还要承受季节温差的影响。为研究温度荷载对双螺旋单层网壳结构的影响,对该工程进行了施工过程中的温度场和应力场监测;在膜结构施工完成后继续进行了一年的健康监测。通过将膜结构安装之前和安装之后的监测结果进行对比,揭示了膜结构对双螺旋单层网壳结构在太阳辐射不均匀温度场作用下的力学响应的影响。
[Abstract]:With the development of economy, construction engineering to further expand the scale, complexity is further improved, and built a number of complicated shape of large span steel structure. The large span space structure geometry, material properties and boundary conditions are often dramatic changes in the construction process, the internal force and deformation caused by the load at the completion of each construction step is by the effect are the accumulation of completion is closely related to the distribution of internal force and deformation of each component and the actual construction process. At the same time, the construction process is often the most dangerous stage in the life cycle of building structure, according to incomplete statistics, the relevant departments of the state, in the collapse of our country about engineering structure more than 2/3 accidents during the construction period, the reason is not considering the complexity of the structure in the construction process. Because of the wide area, construction mechanics of the theoretical research in many aspects It is still not very mature, such as the construction process of the numerical simulation theory, calculation theory of the bearing capacity of the scaffolding theory to optimize the construction process, the welding effect on the mechanical properties, the construction process of the wind-induced response analysis theory. In addition, key problems caused by solar radiation on the temperature field of the structure construction and mechanical properties are not uniform during the service it is urgent to solve. Birth and death element method is widely used to simulate the construction of large-span space structure, the principle of stiffness matrix is multiplied by the component will be installed without a small enough not to reduce the component factor contribution to the structure will be installed, that can be ignored. But due to the birth and death element method, component kill not really removed from the structure, these elements will be on the public node "dead unit" and "work unit" as the boundary displacement is produced, the so-called "drift". For G Take this malpractice, based on the step-by-step modeling method on the concept of the two development of universal finite element software, and puts forward the method of simulating the construction unit can avoid the dead "drift". At the same time, based on actual engineering Jiabao transport hub construction process as the background of the whole construction process of construction the simulation system, studies the component lifting area in the process of ascension of the stress change trend, and has carried on the simulation of field monitoring. In the proposed construction on the basis of the theory, this paper studied the ultimate bearing capacity of the gantry scaffolding. Scaffolding used in large span node space structure construction process is affected by mechanical properties of complex. Connections between different modules with semi rigid obvious features. This paper proposes a simulation algorithm to consider efficient numerical semi rigid joints, and considering bending component defects. Ring. Studied the ultimate bearing capacity based on the gantry scaffolding system. Because of the complexity of large complex structure construction, the construction process often requires dozens of supporting frame. For space structures with complex shapes, such as Jiabao transport hub, supporting point selection is very complex, how to choose the combination support the best for engineering and technical personnel, it is a big problem, in addition, to determine the optimal sequence of unloading, integral lifting lifting point selection is very important for the safety of construction. The real number encoding genetic algorithm to optimize the above based on a series of problems. In addition, combining with the particularity of Jiabao traffic hub, the support stiffness was optimized using binary encoding genetic algorithm. At present, in the construction process, a large number of common welding work. In this paper Jiabao transport hub of the whole welding structure as engineering background, the welding residual stress of thick steel plate were studied, and the influence of node box component, mechanical properties of the welded cross clapboard. The welding residual stress, stress calculation method of implantation of whole structure, greatly saves the computing time, making the whole structure in considering the welding residual stress becomes a possibility. In addition, this paper also put forward by changing the mechanical properties of the material to consider the method of welding residual stress, and the actual engineering are analyzed. Frequency domain analysis method based on random vibration, the proper orthogonal decomposition method combined with pseudo excitation method, put forward the syndrome the pseudo excitation method for space structure, greatly reduces the computational cost. The proposed method is applied to analyze the wind vibration response to enhance the overall structure, the results show that the method for the fundamental frequency is Low flexible structure has high computational efficiency and accuracy. The construction period of large span space structure is generally very long, so the structure in the construction process should not only bear the daily temperature change, but also bear the effects of seasonal difference. In order to study the effect of temperature load on the double helix single layer reticulated shell structure, the construction of the temperature field in the process of construction and stress field monitoring; to continue the health monitoring for one year in the completion of the construction of membrane structure. The membrane structure installation monitoring before and after installation of the results were compared to reveal the effect of membrane structure on the mechanical response of the double helix single layer reticulated shell structure in the solar radiation non uniform temperature field under the action of.

【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TU765
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本文编号：1510214