为考查时域分析方法用于桥梁抖振分析的可行性和可靠性,基于相同的分析参数,分别采用时域和频域分析方法对一斜拉桥的抖振响应进行分析,并从结构振动型态、抖振响应均方根及抖振响应功率谱密度函数三个方面对时域和频域分析结果的一致...为考查时域分析方法用于桥梁抖振分析的可行性和可靠性,基于相同的分析参数,分别采用时域和频域分析方法对一斜拉桥的抖振响应进行分析,并从结构振动型态、抖振响应均方根及抖振响应功率谱密度函数三个方面对时域和频域分析结果的一致性进行了较详细的比较。时域抖振响应分析中,采用谱解法模拟了斜拉桥的脉动风场,抖振力采用准定常表达形式,自激力采用Y.K. Lin 表达形式。由于自激力的存在,结构的运动方程为非线性,提出了一种迭代方法来考虑自激力引起的非线性。采用Newmark-β方法进行积分计算。频域抖振分析采用多模态耦合分析方法。时域及频域抖振响应分析结果的一致性较好,这表明了大跨度斜拉桥时域抖振响应分析的可行性和可靠性。展开更多
In this dissertation, wind, vehicle and bridge are regarded as an interacting coupling vibration system. In the analysis model of the system, many factors are considered in detail, such as the fluid-solid coupling int...In this dissertation, wind, vehicle and bridge are regarded as an interacting coupling vibration system. In the analysis model of the system, many factors are considered in detail, such as the fluid-solid coupling interaction between wind and bridge, the solid contact coupling interaction between vehicle and bridge, the stochastic wind load of vehicle, the time variation characteristics of the system induced by train movement. The main research achievements are as follows:Firstly, a reliable but simple identification method by the name of the Weighting Ensemble Least-Square method (WELS), has been developed to extract flutter derivatives of bridge deck from free vibration records. According to the properties of both the structural style and the vibration mode of long cable-stayed bridge, and considering the correlation characteristics of natural wind, a practical method is introduced to simplify stochastic wind velocity field of long cable-stayed bridges for taking pylon wind field effect into account. The method turns a three-dimension stochastic wind field on a plane into one-dimension stochastic wind fields on lines. The computational work of simulating wind velocity field is reduced by a big margin by the method. Based on wind speed observation record with drawback, it is proved that the exponent expressing terrain roughness can be calculated according to the monthly maximum wind speed records at various height levels. Wind gradient characteristics on bridge site are determined by statistical method. In order to measure respective aerodynamic parameters of deck and vehicle when vehicle is on deck, a simple but well-performed device is developed, which is called Crossed Slot System. The device can separate the wind loads on bridge and on vehicles from each other. Based measured aerodynamic parameter and simulated wind speed field, time-domain expression of static wind load, buffeting load and self-excited load for bridge and vehicle are introduced.Secondly, Germany high-speed spectrums with weak disturbance are adopted to simulate the stochastic rail irregularities. Iterative methods are developed to calculate the geometric relationship and interaction force between wheel and rail. Based the geometric and mechanical coupling relation between vehicle and bridge, movement equation of wind-vehicle-bridge system is established. The equation can be solved by a separated iterative procedure, which can consider various nonlinear factors. According to the theory presented in this dissertation and author’s long time research practice, computational software, BANSYS (Bridge ANalysis SYStem), is developed by the Windows technique of Visual C++.Finally, Nanjing Yangtze River Bridge on Beijing-Shanghai high-speed railway, a three-pylon cable-stayed bridge, is analyzed. The buffeting analysis result of time domain is compared with that of frequency domain. The effects of pylon wind speed field and nonlinear factors are taken into account. It is shown that in buffeting analysis that the analysis results of time domain agree well with those of frequency domain. Effect of pylon wind field can increase the lateral buffeting response of pylon. Nonlinear factor can decrease the nature frequency of cable-stayed bridge and increase the vertical and tensional buffeting response. In wind-vehicle-bridge system vibration analysis, a set of indexes is presented to indicate the level of bridge vibration. In addition, the effects of wind field model, wind speed, train speed, relative location of vehicle and nonlinear factors of the system vibration are analyzed by various case comparisons. It is shown in wind-vehicle-bridge system vibration analysis that cross wind action can remarkably increase the response of bridge and vehicle. Generally, the response of bridge and vehicle increases with wind speed and train speed. In the case that when the vehicle is on the leeward side of deck it is more dangerous than other cases when the vehicle is on the windward side of the deck. Nonlinear factors can influence the bridge more than the vehicle.展开更多
文摘为考查时域分析方法用于桥梁抖振分析的可行性和可靠性,基于相同的分析参数,分别采用时域和频域分析方法对一斜拉桥的抖振响应进行分析,并从结构振动型态、抖振响应均方根及抖振响应功率谱密度函数三个方面对时域和频域分析结果的一致性进行了较详细的比较。时域抖振响应分析中,采用谱解法模拟了斜拉桥的脉动风场,抖振力采用准定常表达形式,自激力采用Y.K. Lin 表达形式。由于自激力的存在,结构的运动方程为非线性,提出了一种迭代方法来考虑自激力引起的非线性。采用Newmark-β方法进行积分计算。频域抖振分析采用多模态耦合分析方法。时域及频域抖振响应分析结果的一致性较好,这表明了大跨度斜拉桥时域抖振响应分析的可行性和可靠性。
文摘In this dissertation, wind, vehicle and bridge are regarded as an interacting coupling vibration system. In the analysis model of the system, many factors are considered in detail, such as the fluid-solid coupling interaction between wind and bridge, the solid contact coupling interaction between vehicle and bridge, the stochastic wind load of vehicle, the time variation characteristics of the system induced by train movement. The main research achievements are as follows:Firstly, a reliable but simple identification method by the name of the Weighting Ensemble Least-Square method (WELS), has been developed to extract flutter derivatives of bridge deck from free vibration records. According to the properties of both the structural style and the vibration mode of long cable-stayed bridge, and considering the correlation characteristics of natural wind, a practical method is introduced to simplify stochastic wind velocity field of long cable-stayed bridges for taking pylon wind field effect into account. The method turns a three-dimension stochastic wind field on a plane into one-dimension stochastic wind fields on lines. The computational work of simulating wind velocity field is reduced by a big margin by the method. Based on wind speed observation record with drawback, it is proved that the exponent expressing terrain roughness can be calculated according to the monthly maximum wind speed records at various height levels. Wind gradient characteristics on bridge site are determined by statistical method. In order to measure respective aerodynamic parameters of deck and vehicle when vehicle is on deck, a simple but well-performed device is developed, which is called Crossed Slot System. The device can separate the wind loads on bridge and on vehicles from each other. Based measured aerodynamic parameter and simulated wind speed field, time-domain expression of static wind load, buffeting load and self-excited load for bridge and vehicle are introduced.Secondly, Germany high-speed spectrums with weak disturbance are adopted to simulate the stochastic rail irregularities. Iterative methods are developed to calculate the geometric relationship and interaction force between wheel and rail. Based the geometric and mechanical coupling relation between vehicle and bridge, movement equation of wind-vehicle-bridge system is established. The equation can be solved by a separated iterative procedure, which can consider various nonlinear factors. According to the theory presented in this dissertation and author’s long time research practice, computational software, BANSYS (Bridge ANalysis SYStem), is developed by the Windows technique of Visual C++.Finally, Nanjing Yangtze River Bridge on Beijing-Shanghai high-speed railway, a three-pylon cable-stayed bridge, is analyzed. The buffeting analysis result of time domain is compared with that of frequency domain. The effects of pylon wind speed field and nonlinear factors are taken into account. It is shown that in buffeting analysis that the analysis results of time domain agree well with those of frequency domain. Effect of pylon wind field can increase the lateral buffeting response of pylon. Nonlinear factor can decrease the nature frequency of cable-stayed bridge and increase the vertical and tensional buffeting response. In wind-vehicle-bridge system vibration analysis, a set of indexes is presented to indicate the level of bridge vibration. In addition, the effects of wind field model, wind speed, train speed, relative location of vehicle and nonlinear factors of the system vibration are analyzed by various case comparisons. It is shown in wind-vehicle-bridge system vibration analysis that cross wind action can remarkably increase the response of bridge and vehicle. Generally, the response of bridge and vehicle increases with wind speed and train speed. In the case that when the vehicle is on the leeward side of deck it is more dangerous than other cases when the vehicle is on the windward side of the deck. Nonlinear factors can influence the bridge more than the vehicle.
