大跨度悬索桥地震动响应影响因子及易损性研究
发布时间：2019-06-26 21:38
【摘要】：改革开放以来特别是近十几年新中国的悬索桥发展十分迅速,随着经济发展的需要全国各地新建了很多的悬索桥,悬索桥日渐成为我国交通的重要组成部分。研究悬索桥的动力特性及自振特性对于了解悬索桥在地震作用下的动力反应具有十分重要的意义,也是悬索桥抗震设计的基础。虽然到目前为止还没有悬索桥在地震中遭到破坏,但是由于悬索桥的造价十分高昂,一旦破坏修护起来非常困难且维修费用很高,并且由此造成的交通中断也会给社会经济发展带来巨大的损失。况且,由于地震作用的复杂性和悬索桥结构自身的特点,目前并没有具有普遍适用意义的关于悬索桥抗震设计的规范。因此,研究桥梁结构参数对自振特性及地震动响应的影响,分析悬索桥结构在地震作用下的薄弱环节,找到最优结构形式,进而为今后悬索桥设计提供依据,就具有非常重要的现实意义。本文依托青草背长江大桥为初始模型,根据其工程概况采用大型有限元分析软件Midas/civil建立了分析模型,依次分析了桥面质量、主梁刚度、主缆刚度、主塔刚度以及矢跨比的变化对悬索桥自振特性的影响。通过分析得到:桥面系质量和矢跨比对于悬索桥自振特性的影响是最大的,加劲梁刚度次之;而主塔刚度对体系的频率和固有振型几乎没有任何影响。主梁竖向振动和横向振动受桥面系质量的影响较大,随着桥面系质量的增加,横向自振频率和竖向自振频率减少。主缆刚度的变化对竖弯的影响比较明显。改变悬索桥的矢跨比,会使悬索桥自振特征阶次重新排序,减小矢跨比将使各主要振型的频率升高。然后计算分析桥面系恒载、主梁刚度、主缆刚度和主塔刚度对悬索桥地震动响应的影响。得出改变不同的参数,在不同方向的地震波作用下,悬索桥关键部位的响应敏感性不尽相同,进而运用能力/需求比法,对青草背大桥主塔在顺桥向+竖向地震波和横桥向+竖向地震波作用下进行易损性分析,得到了青草背大桥该桥主塔薄弱环节发生在顺桥向+竖向地震波作用下,主塔根部、主塔塔高在0m~24m和80m~140m处。
[Abstract]:Since the reform and opening up, especially in recent years, the suspension bridge in New China has developed very rapidly. with the needs of economic development, many new suspension bridges have been built all over the country, and suspension bridges have increasingly become an important part of traffic in our country. It is of great significance to study the dynamic and natural vibration characteristics of suspension bridges for understanding the dynamic response of suspension bridges under earthquake, and it is also the basis of seismic design of suspension bridges. Although up to now, no suspension bridge has been damaged in the earthquake, but because of the high cost of the suspension bridge, once the damage and repair is very difficult and the maintenance cost is very high, and the traffic interruption will also bring great losses to the social and economic development. Moreover, due to the complexity of seismic action and the characteristics of suspension bridge structure, there is no code for seismic design of suspension bridge. Therefore, it is of great practical significance to study the influence of bridge structural parameters on natural vibration characteristics and ground motion response, to analyze the weak links of suspension bridge structure under earthquake action, to find the optimal structural form, and to provide the basis for the design of suspension bridge in the future. In this paper, based on the Qingcaobi Yangtze River Bridge as the initial model, according to its engineering situation, the analysis model is established by using the large-scale finite element analysis software Midas/civil. The effects of bridge deck mass, main beam stiffness, main cable stiffness, main tower stiffness and rise-span ratio on the natural vibration characteristics of suspension bridge are analyzed in turn. Through the analysis, it is found that the mass of the bridge deck system and the ratio of rise to span have the greatest influence on the natural vibration characteristics of the suspension bridge, followed by the stiffness of the stiffened beam, while the stiffness of the main tower has little effect on the frequency and natural vibration mode of the system. The vertical vibration and transverse vibration of the main beam are greatly affected by the quality of the bridge deck system. With the increase of the quality of the bridge deck system, the transverse natural vibration frequency and vertical natural vibration frequency decrease. The influence of the stiffness of the main cable on the vertical bending is obvious. By changing the rise-span ratio of the suspension bridge, the natural vibration characteristic order of the suspension bridge will be reordered, and the frequency of the main vibration modes will be increased by reducing the rise-span ratio. Then the effects of bridge deck system dead load, main beam stiffness, main cable stiffness and main tower stiffness on the ground motion response of suspension bridge are calculated and analyzed. It is concluded that the response sensitivity of the key parts of the suspension bridge is not the same under the action of different seismic waves in different directions, and then the vulnerability of the main tower of Qingcaobi Bridge under the action of vertical seismic wave and vertical seismic wave of the bridge is analyzed by using the capacity / demand ratio method. It is obtained that the weak link of the main tower of Qingcaobei Bridge occurs under the action of vertical seismic wave along the bridge and the root of the main tower. The main tower is high at 0m~24m and 80m~140m.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U442.55
本文编号：2506515
[Abstract]:Since the reform and opening up, especially in recent years, the suspension bridge in New China has developed very rapidly. with the needs of economic development, many new suspension bridges have been built all over the country, and suspension bridges have increasingly become an important part of traffic in our country. It is of great significance to study the dynamic and natural vibration characteristics of suspension bridges for understanding the dynamic response of suspension bridges under earthquake, and it is also the basis of seismic design of suspension bridges. Although up to now, no suspension bridge has been damaged in the earthquake, but because of the high cost of the suspension bridge, once the damage and repair is very difficult and the maintenance cost is very high, and the traffic interruption will also bring great losses to the social and economic development. Moreover, due to the complexity of seismic action and the characteristics of suspension bridge structure, there is no code for seismic design of suspension bridge. Therefore, it is of great practical significance to study the influence of bridge structural parameters on natural vibration characteristics and ground motion response, to analyze the weak links of suspension bridge structure under earthquake action, to find the optimal structural form, and to provide the basis for the design of suspension bridge in the future. In this paper, based on the Qingcaobi Yangtze River Bridge as the initial model, according to its engineering situation, the analysis model is established by using the large-scale finite element analysis software Midas/civil. The effects of bridge deck mass, main beam stiffness, main cable stiffness, main tower stiffness and rise-span ratio on the natural vibration characteristics of suspension bridge are analyzed in turn. Through the analysis, it is found that the mass of the bridge deck system and the ratio of rise to span have the greatest influence on the natural vibration characteristics of the suspension bridge, followed by the stiffness of the stiffened beam, while the stiffness of the main tower has little effect on the frequency and natural vibration mode of the system. The vertical vibration and transverse vibration of the main beam are greatly affected by the quality of the bridge deck system. With the increase of the quality of the bridge deck system, the transverse natural vibration frequency and vertical natural vibration frequency decrease. The influence of the stiffness of the main cable on the vertical bending is obvious. By changing the rise-span ratio of the suspension bridge, the natural vibration characteristic order of the suspension bridge will be reordered, and the frequency of the main vibration modes will be increased by reducing the rise-span ratio. Then the effects of bridge deck system dead load, main beam stiffness, main cable stiffness and main tower stiffness on the ground motion response of suspension bridge are calculated and analyzed. It is concluded that the response sensitivity of the key parts of the suspension bridge is not the same under the action of different seismic waves in different directions, and then the vulnerability of the main tower of Qingcaobi Bridge under the action of vertical seismic wave and vertical seismic wave of the bridge is analyzed by using the capacity / demand ratio method. It is obtained that the weak link of the main tower of Qingcaobei Bridge occurs under the action of vertical seismic wave along the bridge and the root of the main tower. The main tower is high at 0m~24m and 80m~140m.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U442.55
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1 白宗琨;基于空间变化特性的地震动模拟及悬索桥地震反应分析[D];大连理工大学;2007年
本文编号：2506515
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