考虑损伤的单层球面网壳动力失效理论及试验研究

发布时间：2018-04-29 14:42

本文选题：单层球面网壳 + 纤维损伤　；参考：《北京工业大学》2015年博士论文

【摘要】：单层球面网壳由于其轻盈,优美等众多优点,被广泛应用于当代大跨空间结构之中。然而近年来地震的频发,单层球面网壳的动力失效问题成为当前研究热点。本文主要从以下几个方面进行深入探讨:考虑材料损伤,从能量角度探索单层球面网壳动力失效判别准则;进行单层球面网壳动力失效的全过程试验;建立结构损伤演化模拟的隐式算法,研究动力作用下单层球面网壳损伤的发展过程及结构动力失效的全过程,最后结合计算机模拟结果及试验结果,研究提高单层球面网壳抗失效能力的方法。主要工作与结论有:(1)建立了基于杆件纤维损伤的结构损伤演化模拟方法对于杆件的材料损伤,结合ABAQUS中材料子程序的FRTRAN接口,考虑材料的损伤累积过程,编写材料子程序。通过把空间杆件截面划分为多个积分点,实现了截面纤维损伤计算,进而从微观角度观察材料损伤的变化过程。根据纤维失效给出杆件刚度变化并形成了隐式算法。结合已有的几个试验结果,进行计算机模拟,验证了材料子程序和模拟方法的正确性。从而为进一步研究单层球面网壳的动力损伤过程奠定了基础。(2)进行了基于时效的单层球壳损伤演化及震后承载力分析采用本文建立的结构损伤演化模拟方法,对一单层球面网壳模型进行强震作用下的响应分析。结果表明:随着地震作用的持续,单层球面网壳失效具有从单元体破坏开始,逐步发展的特点;探讨了结构损伤以致失效的演化规律,给出了单层球面网壳的失效模式。进一步通过对不同时长、不同PGA情况下单层球壳极限承载力分析,得出对于震后结构极限承载力的评估,需要同时考虑地震峰值的大小和作用时长的结论,并拟合出单层球面网壳震后承载力和多参数之间的函数关系,这对震后结构的安全评定,具有重要意义。(3)提出了基于动能的单层球面网壳动力失效判别准则振动过程中结构动能必然发生波动,而发生动力失效时结构动能必将发生剧烈变化。为此,本文避开采用塑性应变能或最大位移通过统计作为失效判别指标,从动能的角度去探讨一种判别单层球面网壳动力失效的准则。通过研究动能增量的变化形式与单层球面网壳失效可能性的关系,结合动能增量振动曲线,提出了单层球面网壳动力失效判别准则。该准则简洁、明了,并且有利于程序的实现。算例分析表明该准则对于单层球面网壳稳定破坏和强度破坏均有效。(4)基于Python开发ABAQUS,实现了结构失效自动判断功能通过ABAQUS的脚本接口,该接口在Python语言的基础上进行的定制开发,采用Python语言编写的程序,通过脚本接口直接和软件内核进行对话。结合基于动能的单层球面网壳失效判别准则,编写基于IDA的计算程序,从而实现ABAQUS在单层球面网壳动力计算过程中的结构失效自动判断功能。(5)成功地实现了单层球面网壳动力失效全过程试验通常由于动力破坏的突然性而难以通过试验得到结构失效的全过程。本文利用现有的试验室条件,针对一个单层球面网壳的振动台试验,通过低频调幅加载获得杆件陆续进入塑性的规律,从而可评估结构的损伤程度;通过基频简谐加载获得节点位移时程,从而实现了结构失效全过程的监测。并通过该试验验证了本文建立的结构损伤演化模拟方法和单层球面网壳动力失效判别准则。(6)提出了提高单层球面网壳抗失效能力的措施试验与数值模拟均表明在强震作用下,单层球面网壳的环向杆件最先进入塑性,而且由于存在弯矩的作用均是杆件根部先进入塑性。本着延缓结构塑性发展的原则,通过多种工况对比分析不同环杆加强后结构的塑性发展情况,最后得出了对于施威德勒型网壳加强跨度1/4处的环杆和加大杆件根部均为有效的措施。根据本文提出的动力失效判别准则,采取措施后结构失效时刻得以明显延迟。
[Abstract]:Single layer spherical reticulated shell has been widely used in modern large span space structure because of its advantages of lightness, grace and so on. However, in recent years, the dynamic failure of single layer spherical reticulated shell has become a hot topic in recent years. This paper is mainly to discuss the following aspects: considering material damage and exploring single layer from the angle of energy The dynamic failure criterion of the spherical reticulated shell, the whole process test of the dynamic failure of the single layer reticulated shell, the implicit algorithm of the structural damage evolution simulation, the development process of the damage of the single layer spherical reticulated shell under dynamic action and the whole process of the dynamic failure of the structure are studied. Finally, the improvement of the single layer is studied in combination with the simulation results and the experimental results. The main work and conclusions are as follows: (1) a structural damage evolution simulation method based on rod fiber damage is established for material damage of rod, combined with the FRTRAN interface of the material subroutine in ABAQUS, considering the damage accumulation process of the material, and compiling the subprogram of material. Several integral points are used to calculate the fiber damage of the section, and then the change process of material damage is observed from the microcosmic angle. According to the fiber failure, the change of the stiffness of the rod is given and the implicit algorithm is formed. The computer simulation is carried out with several experimental results. The correctness of the material subprogram and the simulation method is verified. The study of the dynamic damage process of single layer spherical reticulated shell has laid the foundation. (2) the damage evolution of single layer spherical shell based on aging and the analysis of post earthquake bearing capacity are used to simulate the structural damage evolution in this paper, and the response analysis of a single layer spherical reticulated shell model under strong earthquake action is carried out. The results show that with the continuous earthquake action, the single spherical reticulated shell model is subjected to the response analysis. The failure of the layer spherical reticulated shell has the characteristics of the beginning of the failure of the unit body and the gradual development. The evolution law of the structural damage and failure is discussed. The failure mode of the single layer spherical reticulated shell is given. The ultimate bearing capacity of the single layer spherical shell in different time length and different PGA conditions is analyzed, and the evaluation of the ultimate bearing capacity of the structure after the earthquake is obtained. It is necessary to take the conclusion of the magnitude of the earthquake peak and the length of action at the same time, and fit the function relation between the post earthquake bearing capacity and the multi parameters of the single layer spherical reticulated shell, which is of great significance to the safety assessment of the post earthquake structure. (3) the dynamic energy of the dynamic failure of the single layer spherical reticulated shell based on the kinetic energy is proposed. In this paper, a criterion for determining the dynamic failure of a single layer reticulated spherical reticulated shell is discussed from the point of view of kinetic energy. The relationship between the failure possibility of the reticulated shell and the kinetic energy increment vibration curve, a criterion for the dynamic failure of the single layer spherical reticulated shell is proposed. The criterion is concise, clear and beneficial to the realization of the program. The example analysis shows that the criterion is effective for the stability and strength failure of a single layer spherical reticulated shell. (4) the structure is developed based on Python, and the structure is realized. The function of automatic failure judgment is made through the script interface of ABAQUS. The interface is developed on the basis of the Python language, the program written in the Python language is written in the language, and the software kernel is dialogically dialogically with the script interface. It combines the failure criterion of the single layer spherical reticulated shell based on the kinetic energy, and writes the computing program based on the IDA to realize the AB AQUS in the dynamic calculation of the single layer spherical reticulated shell. (5) the whole process test of the dynamic failure of the single layer spherical reticulated shell is successfully realized. The whole process of structural failure is difficult to be obtained by the test of the dynamic failure. The shaking table test of the shell is used to obtain the plastic law of the member through the low frequency amplitude modulation loading, thus the damage degree of the structure can be evaluated. The displacement time history of the node is obtained through the basic frequency simple harmonic loading, thus the whole process of structural failure is monitored. The simulation method and single layer of structural damage evolution established in this paper has been verified by the experiment. The criterion for dynamic failure of a spherical reticulated shell. (6) the test and numerical simulation of improving the anti failure ability of a single-layer spherical reticulated shell show that the ring member of a single-layer spherical reticulated shell is the first to enter the plastic under strong earthquake action, and the effect of the moment is the advanced plasticity of the root of the member. In principle, through a variety of working conditions, the plastic development of the reinforced structure with different ring bars is analyzed. Finally, the effective measures are obtained for the reinforcement of the ring rod and the root of the member at 1/4 span of the schwedeler type reticulated shell. According to the dynamic failure criterion proposed in this paper, the failure time of the structure is obviously delayed.

【学位授予单位】：北京工业大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TU399;TU317

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