风及车辆荷载作用下大跨度悬索桥的动力响应分析

发布时间：2018-09-06 06:50

【摘要】：大跨度悬索桥由于其刚度较小，在风、车辆等外荷载作用下会产生较大的内力和变形。因此，对大跨度悬索桥进行动力分析，无论是对桥梁的设计还是维护，都有重要的意义。本文以矮寨大桥为依托，建立了三维桥梁有限元模型，综合考虑车辆与风荷载的作用，对大跨度桥梁的动力响应进行了分析。全文主要包括以下几方面内容： 1.在时域内模拟了我国常见的4种路面不平顺；采用谐波叠加法模拟了桥址处的风速场。 2.分析了车辆荷载单独作用下桥梁的动力响应，得到以下结论： 1）随着路面不平顺等级的增大，桥梁跨中竖向位移、加速度时程曲线振动趋势随之变化，同时动力响应峰值会随之增大，且位移、加速度增长倍数相近。 2）随着车速的提高，桥梁跨中竖向位移、加速度时程曲线振动趋势也随之变化，同时动力响应峰值也呈增长趋势，其中加速度的增长速度要大于位移的。 3）随着车重的增加，，桥梁跨中竖向位移、加速度时程曲线振动趋势几乎没变化，且动力响应呈线性增长。 4）桥梁跨中横向动力响应的产生主要来自桥梁两侧的不平衡力，不平衡性越大，动力响应越大。 3.通过一简支梁、半车模型，分析了车辆上桥前的初始振动对桥梁动力响应的影响，同时对车辆变速行驶的问题进行了研究。得到以下结论： 1）与无初始振动的情况相比，车辆带着一定的初始振动上桥，刚入桥的一段时间内，桥梁的动力响应会明显增大，随着车辆继续行驶，这种影响会慢慢减弱。 2）车辆变速行驶对桥梁动力响应的影响不大，在实际计算中，我们可以不考虑车辆变速行驶的影响。 4.分析了风荷载单独作用及风和车辆荷载同时作用下桥梁的动力响应。得到如下结论： 1）随着风速的增大，桥梁跨中节点各项动力响应均呈增长趋势。 2）在风荷载作用下，迎风面腹杆和背风面腹杆应力时程曲线呈现相反的变化趋势，且在同种风速下，背风面腹杆应力峰值大于迎风面的情况。 3）风荷载主要引起桥梁的横向振动，车辆荷载主要引起桥梁的竖向振动。 4）静风荷载使桥梁向一侧偏移，脉动风在此基础上使桥梁发生振动，随着风速的增大，偏移量和振动都呈增大趋势。
[Abstract]:Due to the small stiffness of long-span suspension bridge, large internal force and deformation will occur under external loads such as wind and vehicle. Therefore, the dynamic analysis of long-span suspension bridge is of great significance to the design and maintenance of the bridge. In this paper, based on the Aizhai Bridge, a three-dimensional finite element model of the bridge is established, and the dynamic response of the long-span bridge is analyzed synthetically considering the action of vehicle and wind load. The full text mainly includes the following aspects: 1. In this paper, four kinds of road surface irregularity are simulated in time domain, and the wind velocity field at bridge site is simulated by harmonic superposition method. 2. 2. The dynamic response of the bridge under vehicle load alone is analyzed. The following conclusions are obtained: 1) with the increase of the road surface irregularity grade, the vertical displacement and acceleration time history curve vibration trend of the bridge span changes with the increase of the road surface irregularity grade. At the same time, the peak value of dynamic response will increase, and the displacement and acceleration increase times will be similar. 2) with the increase of speed, the vertical displacement of bridge span and the vibration trend of acceleration time history curve will also change. At the same time, the peak value of dynamic response also shows an increasing trend, in which the acceleration increases faster than the displacement. 3) with the increase of the vehicle weight, the vertical displacement of the bridge span and the vibration trend of the acceleration time-history curve are almost unchanged. And the dynamic response increases linearly. 4) the transverse dynamic response of the bridge is generated mainly from the unbalanced force on both sides of the bridge. The greater the unbalance, the greater the dynamic response. Based on a simply supported beam and half-car model, the influence of the initial vibration on the dynamic response of the bridge is analyzed. At the same time, the problem of vehicle driving with variable speed is studied. The following conclusions are obtained: 1) compared with the case of no initial vibration, the dynamic response of the bridge will increase obviously when the vehicle is on the bridge with a certain initial vibration, and the dynamic response of the bridge will increase obviously as the vehicle continues to drive. This effect will weaken slowly. 2) the effect of vehicle speed change on bridge dynamic response is not significant. In actual calculation, we can not consider the effect of vehicle speed change. 4. The dynamic response of the bridge under the action of wind load alone and the simultaneous action of wind and vehicle loads is analyzed. The main conclusions are as follows: 1) with the increase of wind speed, the dynamic responses of the mid-span joints of the bridge show an increasing trend. 2) under the action of wind load, The stress time history curves of upwind and leeward webs show a reverse trend, and the peak stress of leeward web is larger than that of upwind under the same wind speed. 3) the transverse vibration of bridges is mainly caused by wind load. The vehicle load mainly causes the vertical vibration of the bridge. 4) the static wind load causes the bridge to deviate to one side, and the pulsating wind makes the bridge vibrate on this basis. With the increase of the wind speed, the deviation and vibration tend to increase.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U448.25;U441.3

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