古建结构荷载、刚度等关键参数识别及工作状态评估研究

发布时间：2018-05-11 11:25

  本文选题：结构状态评估 + 古建筑木结构　； 参考：《北京交通大学》2017年博士论文

【摘要】：古代建筑是先人为我们留下的珍贵文化瑰宝,具有历史、文化、科技、艺术等多方面价值。古代建筑建造年代久远,在其服役过程中会受到环境荷载作用及材料老化等不利因素,结构不可避免的产生损伤积累和抗力衰减。使得很多古建筑的结构安全状态令人担忧,甚至具有局部破坏或整体坍塌的可能性。这不仅会带来巨大的经济损失和人员伤亡,从遗产保护的角度来说,这种破坏带来的后果是灾难性的。因此,对古建筑结构的安全性进行评估是非常重要和紧迫的。考虑到古建筑材料受自然环境影响而退化;结构内部构件连接松动会导致节点刚度退化;结构内部损伤累积导致承载力较弱,不宜通过加载试验确定结构参数,本文的主要目的是提出基于环境激励的结构工作状态评估方法。工作状态评估内容主要包括安全性、适用性和耐久性三个方面。安全性是指结构承载能力评估,与结构和构件刚度和稳定性能有关;适用性是指结构的工作极限状态评估,与结构和构件在荷载作用下的变形、振动等有关;耐久性主要指对结构损伤的评估。为达成上述研究目的,拟解决如下三个问题:1)在不同荷载作用下,结构的动力特性如何?2)作用在结构上的荷载情况如何考虑?3)古建结构中未知的节点参数和边界条件如何确定?因此,本论文的研究内容主要如下:本文研究目的是提出适用于古代建筑的结构状态性能评估方法。(1)对结构健康监测的数据分析表明,外荷载与结构参数的变化对结构自振频率和阻尼比均有显著影响。利用结构动态测试数据来诊断结构是否发生损伤,进而提出修复方案,其最大优点是将导致结构振动的外界因素作为激励源,可以在不进行加载的情况下完成结构损伤的在线监测与诊断。本部分详细介绍了结构动力监测系统,研究了该结构在多种荷载作用下的动力响应特性及结构状态,并基于长期的监测数据,计算得到结构在不同工作状态下结构动力性能参数变化的情况,为监测系统构建合理的预警机制,获得相对完备的安全状态评估系统所需信息及评价指标做出贡献,并得到如下成果与结论:通过为期三年的动力监测,基于协方差驱动状态子空间法和奇异谱分解法分析获得了结构响应与客流数量、温度和地震作用的关系。其中结构的第一、三阶频率更容易受到人群荷载的影响,在分析游客数量对结构作用影响时该两阶频率对应的信号可以作为主要研究对象;结构第一、二阶频率更容易受到温度变化的影响,在温度对结构作用影响时该两阶频率对应的信号可以作为主要研究对象;地震作用对结构的频率和加速度信号有很重要的影响,但作用将会在一段时间后消失。地震作用将激发结构更多频率峰值的出现,同时原有的一些频率对应的峰值会被削弱。(2)建筑结构在正常使用情况下受到人群荷载、温度荷载、地震作用和风荷载等多种荷载的作用。如何反映建筑结构上的真实荷载状况,对建筑结构的正常维护、安全运营、损伤识别和状态评估具有重要意义。特别是温度荷载对大跨结构、高层建筑结构以及古建木结构影响很大。因此本文提出了可同时识别结构上外部荷载及温度荷载的计算方法。该方法可在温度荷载信息不完备的情况下,将温度荷载从结构外部荷载中进行解耦,从而获得作用在结构上的准确荷载情况。该部分成果与结论如下,此方法可以克服测量噪声的影响,准确的识别出作用在结构上的外部荷载及环境荷载。数值模拟计算结果表明,当考虑10%测量噪声影响时,环境荷载识别结果与理想值误差小于8%,因此可以认为该方法可以准确的识别环境荷载,为古建筑状态评估提供了理论依据。(3)结构参数识别是建立健康监测系统、进行结构损伤识别与状态评估工作的基础,对维护现役结构的安全与正常运营有重要的意义。考虑到古建筑结构节点连接方式复杂,刚度未知,本文提出了一个基于温度灵敏度法对结构参数进行识别并对依据结构初始状态建立的有限元模型予以修正的计算方法。在模型建立中,考虑了构件之间的摩擦作用、存在的缝隙以及暗销的剪切作用,更为准确的模拟了古建筑的工作情况。该方法基于结构动力监测数据,建立了系统输入(环境荷载)与系统输出(结构响应)之间的关系,从而对结构中刚度不确定的构件进行了准确的参数识别并提出了一种有效的边界条件简化方式,以便更合理的表示出古建筑木结构状态的变化,进而为古建筑状态评估奠定基础。计算结果表明,该方法抗噪性强,准确度高。将基于该方法计算得到的结果与通过环境激励法计算结果对比,验证了计算方法的可靠性。在此基础上,对该算法中的计算参数进行分析,得到了数据长度、温差大小及传感器布置情况对计算结果的影响。
[Abstract]:Ancient architecture is a precious cultural treasure left for us by the ancestors. It has many aspects of history, culture, science and technology, art and so on. Ancient architecture was built for a long time. In the course of its service, it will be subjected to adverse factors such as environmental load and material aging. The structure inevitably produces damage accumulation and resistance attenuation. It makes many ancient buildings. The state of structural safety is worrying, even with the possibility of local damage or overall collapse. It not only brings huge economic losses and casualties, but the consequences of this destruction are catastrophic from the point of view of heritage protection. Therefore, it is very important and urgent to assess the safety of the structure of the ancient buildings. The ancient building materials are degenerated by the natural environment, and the looseness of the structural internal components will lead to the degeneration of the stiffness of the joints; the internal damage accumulation in the structure leads to the weak bearing capacity. It is not suitable to determine the structural parameters through the loading test. The main purpose of this paper is to put forward the evaluation method of the working state based on the environmental excitation. It mainly includes three aspects of safety, applicability and durability. Safety refers to the evaluation of structural bearing capacity, which is related to structure and component stiffness and stability performance; applicability refers to the evaluation of the working limit state of the structure and the deformation and vibration of the structure and components under the load; the durability mainly refers to the assessment of structural damage. The purpose of this study is to solve the following three questions: 1) how is the dynamic characteristics of the structure under different loads? 2) how to consider the load situation on the structure? 3) how to determine the unknown node parameters and boundary conditions in the ancient construction structure? Therefore, the main contents of this paper are as follows: the purpose of this paper is to put forward the application The structure state performance evaluation method of the ancient building. (1) the data analysis of the structural health monitoring shows that the changes of the external load and the structural parameters have significant influence on the vibration frequency and damping ratio of the structure. As the excitation source, the vibration monitoring and diagnosis of structural damage can be completed without loading. The structural dynamic monitoring system is introduced in detail, and the dynamic response characteristics and structure state of the structure under various loads are studied, and the structure is calculated based on the long-term monitoring data. The changes in the dynamic performance parameters of the structure under different working conditions have contributed to the construction of a reasonable warning mechanism for the monitoring system and the information and evaluation indexes required for a relatively complete safety state assessment system. The following results and conclusions are obtained: the covariance driven state subspace method and the odd one are obtained through three years of dynamic monitoring. The relationship between the structure response and the number of passenger flow, the temperature and the earthquake action is obtained. The first, third order frequency of the structure is more easily affected by the load of the crowd. The signal corresponding to the two order frequency can be used as the main object in the analysis of the influence of the number of tourists on the structure. The first, second order frequency of the structure is more capacitive. It is easy to be affected by the temperature change, the signal corresponding to the two order frequency can be used as the main research object when the temperature is affected by the structure. The seismic action has a very important influence on the frequency and acceleration signal of the structure, but the effect will disappear after a period of time. Some of the corresponding peaks will be weakened. (2) under normal use, the building structure is subjected to a variety of loads, such as crowd load, temperature load, earthquake action and wind load. How to reflect the real load status in the building structure is important for the normal maintenance of the building structure, safety operation, damage identification and state assessment. In particular, the effect of temperature load on large span structure, high-rise building structure and ancient construction wood structure is very important. Therefore, this paper proposes a method to identify the external load and temperature load on the structure simultaneously. This method can decouple the temperature load from the external load of the structure under the condition of incomplete temperature load information. The results and conclusions are obtained as follows. This method can overcome the influence of measurement noise and accurately identify the external load and environmental load on the structure. The results of numerical simulation show that the error of environmental load identification is smaller than that of the ideal value when the effect of 10% measurement noise is considered. In 8%, it can be considered that this method can accurately identify the environmental load and provide a theoretical basis for the assessment of the state of ancient buildings. (3) the identification of structural parameters is the foundation of establishing a health monitoring system, which is the basis of structural damage identification and state assessment, and is of great significance for the maintenance of the safety and normal operation of the active service structure. The connection mode of structural nodes is complex and the stiffness is unknown. In this paper, a method based on the temperature sensitivity method to identify the structural parameters and to modify the finite element model based on the initial state of the structure is proposed. In the model, the friction between the components, the existing cracks and the shear effect of the pin are considered. It is more accurate to simulate the work of ancient buildings. Based on the dynamic monitoring data of the structure, the relationship between the system input (environmental load) and the system output (structural response) is established, thus the accurate parameter identification of the components with uncertain stiffness in the structure is identified and an effective method of boundary condition simplification is proposed. It is more reasonable to show the change of the structure state of the ancient building wood, and then lay the foundation for the assessment of the state of the ancient building. The calculation results show that the method has strong anti noise and high accuracy. The results of the calculation based on this method are compared with the results calculated by the environmental excitation method, and the reliability of the calculation method is verified. On this basis, the algorithm is used in the algorithm. The calculation parameters are analyzed, and the influence of data length, temperature difference and sensor layout on the calculation results is obtained.

【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TU-87
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本文编号：1873753