弦支结构鲁棒性的理论分析及试验研究

发布时间：2019-03-06 09:46

【摘要】：由于意外事件、结构本身及外荷载的不确定性等引起的干扰,可能会导致结构局部损伤或由此引起整体或连续倒塌。自从1968年伦敦Ronan Point公寓因第18楼瓦斯爆炸或引起阳台连续坍塌以及“9·11”事件以来,这种“结果与起因不相称的破坏”开始引起各国学者的广泛关注,即结构鲁棒性。目前,关于结构鲁棒性的定性及定量研究已不少见,但仍然缺乏普遍可以接受的鲁棒性定量评价标准及设计方法。此外结构鲁棒性的研究对象多集中于桁架、框架、桥梁及网格结构结构等,关于弦支结构鲁棒性的研究较为少见。本文根据外界干扰的性质,分别从初始损伤和不确定性干扰两方面对结构鲁棒性展开研究,并提出基于鲁棒性和连续体拓扑优化的弦支结构鲁棒性设计流程。首先,针对结构鲁棒性评价的确定性指标具有直观简单、易于理解的特点,以杆件截面损伤指数模拟材料的退化效应；推导总结了描述结构性能的指标,定义了一组结构鲁棒性量化指标,并将其运用于桁架结构和弦支结构的鲁棒性评价,分析了各种指标的适用性。结果表明,基于位移二范数和基于应变能的结构鲁棒性指标随杆件损伤指数变化明显,对不同部位结构损伤较为敏感,最适用于结构鲁棒性的评价。其次,从结构及外荷载不确定性的角度出发,基于info-gap理论建立了描述荷载和结构不确定性的数学模型,结合性能需求建立了评价结构在常规荷载和结构属性波动下的鲁棒性指标；针对鲁棒函数求解的嵌套优化问题,采用粒子群算法进行优化,绘制不确定区间模型下的性能曲线,评价了桁架结构和某葵花型弦支结构的鲁棒性。结果表明,基于info-gap决策理论的结构鲁棒指标,能够较好地反映弦支结构不确定性与不相称的破坏的关系,具有直观简单的特点。再次,基于H∞理论,采用结构系统传递函数的H∞范数,作为弦支结构鲁棒性的定量评价指标,以单元密度为设计变量,采用SIMP模型描述材料的刚度,结构鲁棒性为优化目标,将结构鲁棒性设计转化成连续体拓扑优化,并通过粒子群算法求解。以弦支双曲球壳模型为例,通过鲁棒设计得到了鲁棒构型。最后分别通过静力和冲击试验,制造干扰场景,分析不同结构设计方案的鲁棒性。结果表明,H∞结构鲁棒性评价指标可以反映干扰与后果是否相称,通过连续体拓扑优化进行鲁棒设计,能够有效地提高结构鲁棒性,可以为结构初始概念设计提供参考。
[Abstract]:The interference caused by the accident, the structure itself and the uncertainty of the external load, etc., may cause local damage to the structure or thereby cause the whole or the continuous collapse. Since the 1968 London Ronan Point apartment was caused by a gas explosion on the 18th floor or the continuous collapse of the balcony and the "9 路 11" incident, the "disproportion of the result from the cause" began to give rise to a wide range of concerns by scholars, namely, the structural robustness. At present, the qualitative and quantitative research on the structure robustness is not uncommon, but there is still a lack of a generally acceptable standard and design method for robust quantitative evaluation. In addition, the research object of the structure robustness is more and more focused on the structure of frame, frame, bridge and grid structure, and the research on the robustness of the chord structure is very rare. In this paper, based on the nature of the external interference, the structure robustness is studied from the two aspects of initial damage and uncertainty interference, and the robust design process of the chord-branch structure based on the robust and continuum topology optimization is presented. First of all, the deterministic index for structural robustness evaluation has the characteristics of simple and easy to understand, and the degradation effect of the material is simulated with the damage index of the section of the rod; the index of describing the structure performance is derived, and a set of structural robustness quantification is defined. The method is applied to the robust evaluation of the chord branch structure of the frame structure, and the application of the various indexes is analyzed. The results show that the structural robustness index based on the displacement-two-norm and the strain energy is more sensitive to the structural damage of different parts, which is most suitable for the evaluation of the structural robustness. Secondly, based on the angle of structure and external load uncertainty, a mathematical model describing the load and structural uncertainty is established based on the info-gap theory, and the robustness of the evaluation structure under the fluctuation of the conventional load and the structural property is established in combination with the performance requirement. According to the problem of nesting optimization for robust function solution, the particle swarm optimization is used to optimize, and the performance curve under the interval model is drawn. The structure of the frame and the structure of a sunflower type string are evaluated. The results show that the structure robust index based on the information-gap decision theory can better reflect the relationship between the uncertainty of the chord structure and the disproportion of the structure, and has the advantages of being intuitive and simple. In this paper, based on the H-type theory, the H-norm of the transfer function of the structural system is used as the quantitative evaluation index of the robustness of the chord-branch structure, the unit density is the design variable, and the stiffness and the structural robustness of the material are described by the SIMO model. in ord to optimize that objective, the robust design of the structure is transform into a continuum topology optimization, In this paper, a group algorithm is used to solve the problem. The hyperbolic spherical shell model of the string is taken as an example and is obtained by robust design. The robust configuration is obtained. Finally, the interference scene is manufactured by static and shock test, and different structural design parties are analyzed. The results show that the robustness evaluation index of the H-structure can reflect the proportionality of the interference and the result, and the robust design can be effectively improved by the continuous body topology optimization, and the initial concept of the structure can be set for the initial concept of the structure.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU317

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