地面交通激励下古建筑影响及古木结构损伤识别研究

发布时间：2019-07-02 14:07

【摘要】：古建筑在几百年甚至上千年使用过程中,环境侵蚀、材料老化和荷载的长期效应、疲劳效应等因素共同作用下不可避免出现结构系统的损伤积累和抗力衰减。随着城市的经济发展,地面交通车辆密度越来越大,对古建筑的安全产生了重要影响,因此有必要定量评价交通激励下对古建筑的影响,并利用环境激励的结构振动响应数据对古建筑结构进行健康监测和安全评估。西安钟楼和西安城墙是国家重点文物保护单位,本文就地面交通车辆行驶产生的微幅振动对西安钟楼和城墙的影响进行数值分析和安全评估,研究环境激励下基于小波包能量谱的古木结构的损伤识别指标,将其应用到西安钟楼上部木框架的损伤识别中。本文的主要研究内容如下:(1)以西安钟楼和城墙为研究对象,采用数值分析方法建立了钟楼上部木框架-高台基-圆柱形地基和城墙-地基的三维有限元模型,对地面车辆在钟楼环道行驶和从城墙门洞下行驶产生的微幅振动对钟楼和城墙的影响和安全评估进行研究。(2)对随机环境激励下的古木框架结构的损伤进行有限元模拟,采用小波包能量谱建立古木结构的损伤识别指标,并进行小波函数的选择、小波包分解层次的选择、损伤识别指标的损伤敏感性和噪声的影响分析。(3)对随机环境激励下的古木框架结构梁上各节点的加速度响应信号进行小波包分解,提出小波包能量曲率差损伤识别指标对古木结构进行损伤定位,建立损伤指标与损伤程度的关系式并进行古木结构损伤程度的判断,并验算适用性。(4)以西安钟楼为研究对象,对钟楼上部木框架结构的损伤进行有限元模拟,就地面车辆在钟楼环道行驶产生的微幅振动对钟楼结构的影响进行损伤识别研究,采用小波包能量谱建立了钟楼木框架结构的损伤识别指标,从小波函数的选择、小波包分解层次的选择、损伤敏感性和噪声的影响进行了研究。(5)以西安钟楼为研究对象,就地面车辆在钟楼环道行驶产生的微幅振动对钟楼结构的影响进行了损伤识别研究,提出了小波包能量曲率差损伤指标对钟楼上部木框架进行损伤定位,并进行损伤敏感性和噪声的影响分析,建立损伤指标与损伤程度的关系并进行钟楼木框架结构损伤程度的判断。(6)对西安钟楼在地面交通微幅振动下的实测加速度响应信号进行小波包能量谱分析,探讨了钟楼实测小波包能量谱和损伤识别指标—能量比偏差ERVD和能量比方差ERVV能敏感地表征地面交通激励对钟楼振动的影响,适合于环境激励测试下的钟楼结构的实时损伤识别。
[Abstract]:In the course of hundreds or even thousands of years of use, the damage accumulation and resistance attenuation of structural system inevitably occur under the combined action of environmental erosion, material aging, long-term effect of load, fatigue effect and so on. With the economic development of the city, the density of ground traffic vehicles is increasing, which has an important impact on the safety of ancient buildings. Therefore, it is necessary to quantitatively evaluate the impact of traffic incentives on ancient buildings, and to use the vibration response data of structures excited by environmental incentives to carry out health monitoring and safety assessment of ancient buildings. Xi'an bell tower and Xi'an city wall are key cultural relics protection units in Xi'an. This paper makes numerical analysis and safety assessment on the influence of micro vibration caused by ground traffic vehicles on Xi'an clock tower and city wall, studies the damage identification index of ancient wood structure based on wavelet packet energy spectrum under environmental excitation, and applies it to the damage identification of the upper wood frame of Xi'an clock tower. The main research contents of this paper are as follows: (1) taking Xi'an bell tower and city wall as the research object, the three-dimensional finite element models of the upper wooden frame-high platform foundation-cylindrical foundation and wall-foundation of the clock tower are established by using the numerical analysis method. The influence and safety assessment of the micro vibration of ground vehicles on the bell tower and the wall under the ring road of the bell tower and under the gate hole of the city wall are studied. (2) the damage of the ancient wood frame structure excited by random environment is simulated by finite element method, and the damage identification index of the ancient wood structure is established by using the wavelet packet energy spectrum, and the selection of wavelet function and wavelet packet decomposition level is carried out. The damage sensitivity of damage identification index and the influence of noise are analyzed. (3) the acceleration response signals of each node on the beam of ancient wood frame structure excited by random environment are decomposed by wavelet packet, and the damage identification index of energy curvature difference of wavelet packet is put forward to locate the damage of ancient wood structure, and the relationship between damage index and damage degree is established and the damage degree of ancient wood structure is judged. And check the applicability. (4) taking Xi'an bell tower as the research object, the damage of the upper wooden frame structure of the clock tower is simulated by finite element method, and the damage identification research is carried out on the influence of the micro vibration of the ground vehicle on the bell tower structure. The damage identification index of the clock tower wood frame structure is established by using the wavelet packet energy spectrum. From the selection of wavelet function and the selection of wavelet packet decomposition level, the damage identification index of the clock tower wood frame structure is established. The effects of damage sensitivity and noise on the damage sensitivity and noise are studied. (5) taking Xi'an bell tower as the research object, the damage identification of the influence of micro vibration of ground vehicles on the bell tower structure is carried out, and the damage location of the upper wooden frame of the clock tower is analyzed by the damage index of wavelet packet energy curvature difference, and the damage sensitivity and noise are analyzed. The relationship between damage index and damage degree is established and the damage degree of clock tower wooden frame structure is judged. (6) the measured acceleration response signal of Xi'an clock tower under ground traffic micro-amplitude vibration is analyzed by wavelet packet energy spectrum, and the measured wavelet packet energy spectrum and damage identification index-energy ratio deviation ERVD and energy difference ERVV can be sensitive to the influence of ground traffic excitation on the vibration of clock tower. It is suitable for real-time damage identification of bell tower structure under environmental excitation test.
【学位授予单位】：西安建筑科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TU317

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