车桥特性对简支梁桥冲击系数的影响研究

发布时间：2018-09-12 13:55

【摘要】：行驶车辆对桥梁的冲击问题一直受到桥梁研究者们的高度重视，我国《公路桥涵设计通用规范》（04规范）中的冲击系数计算公式只考虑了桥梁基频这一个因素，尽管目前有许多人对简支梁桥受到的汽车冲击作用进行研究，并提出车辆特性和桥梁特性对冲击系数都有一定的影响，但是目前很少有人得出考虑多因素的简支梁桥冲击系数公式。为了给桥梁设计时冲击系数的合理取值提供参考，本文研究了影响简支梁桥冲击系数的主要因素，并提出了考虑多因素的简支梁桥冲击系数参考公式。主要工作与结果如下： 1.运用ANSYS建立简支梁桥模型，并用其模态分析功能求得简支梁桥的前三阶频率，并将结果与理论解进行对比验证了本文桥梁模型的正确性。 2.建立二分之一车辆模型，推导车辆振动方程，利用MATLAB求解车辆振动方程，得出车辆运行时的竖向振动位移、速度和加速度响应。 3.以某简支梁桥为依托，用MATLAB自编程序模拟出了不同等级的桥面不平顺曲线，将得到的不平顺序列作为车轮的位移输入模拟出桥面的不平顺，以车桥接触点的位移联系方程和车桥相互作用力建立车桥耦合模型。并对模型进行了验证，证明了本文车桥耦合模型的可靠性。 4.考虑桥面不平顺、车辆行驶速度、桥梁基频、车辆弹簧刚度、车辆弹簧阻尼、车辆自重6个因素对简支梁桥冲击数的影响，利用ANSYS对车桥耦合模型进行动力分析，得出不同情况下的简支梁桥跨中节点的位移时程曲线和加速度曲线，计算出冲击系数。并对计算结果分析表明，桥面等级、行车速度、车体质量和桥梁基频是影响冲击系数的主要因素，其影响不可忽略。 5.以桥面等级为分项标准，车辆行驶速度和桥梁基频为自变量，通过多元线性回归分析，分别拟合了A、B、C三种桥面等级下针对简支梁桥的冲击系数近似计算公式，并将公式与我国《公路桥涵设计通用规范》进行了对比分析，，得出结论：①规范仅考虑基频的冲击系数计算值只在某种桥面等级下一定速度和基频范围内适用，A级、B级桥面等级下车辆高速行驶时冲击系数普遍偏小，低速时偏大，桥梁基频低频时冲击系数偏大，高频时偏小；C级桥面等级下冲击系数普遍偏小，且低频低速下偏大，高频高速下偏小；②桥梁设计时应根据设计的桥面等级和设计车速及桥梁基频（长度）综合考虑来确定冲击系数的大小。
[Abstract]:The impact of moving vehicles on bridges has been attached great importance to by bridge researchers. The calculation formula of impact coefficient in China's General Code for Highway Bridge and culvert Design (Code 04) only takes into account the fundamental frequency of bridges. Although many people have studied the impact of vehicle on simply supported beam bridges, and put forward that vehicle characteristics and bridge characteristics have a certain impact on the impact coefficient. But at present, few people come up with the formula of impact coefficient of simply supported beam bridge considering many factors. In order to provide a reference for the reasonable selection of impact coefficient in bridge design, this paper studies the main factors that affect the impact coefficient of simply supported beam bridge, and puts forward the reference formula of impact coefficient of simply supported beam bridge considering many factors. The main work and results are as follows: 1. The model of simply supported beam bridge is established by using ANSYS, and the first three order frequency of simply supported beam bridge is obtained by using its modal analysis function. The results are compared with the theoretical solution to verify the correctness of the bridge model in this paper. 2. The model of 1/2 vehicle is established, and the vibration equation of vehicle is deduced. The vertical vibration displacement, velocity and acceleration response of vehicle are obtained by solving the vibration equation of vehicle with MATLAB. Based on a simply supported beam bridge, the irregularity curves of different grades of bridge deck are simulated by MATLAB program, and the resulting irregularity sequence is used as the displacement input of the wheel to simulate the irregularity of the bridge deck. The coupling model of vehicle and bridge is established based on the displacement relation equation of vehicle and bridge contact point and the interaction force between vehicle and bridge. The reliability of the vehicle-bridge coupling model is proved. 4. 4. Considering the influence of six factors, such as bridge deck irregularity, vehicle speed, bridge base frequency, vehicle spring stiffness, vehicle spring damping and vehicle deadweight, on the impact number of simply supported beam bridge, the dynamic analysis of vehicle-bridge coupling model is carried out by using ANSYS. The displacement time history curve and acceleration curve of the middle joint of the bridge span of simply supported beam are obtained under different conditions, and the impact coefficient is calculated. The analysis of the calculated results shows that the main factors affecting the impact coefficient are the bridge deck grade, the driving speed, the mass of the car body and the fundamental frequency of the bridge, which can not be ignored. Based on the grade of bridge deck and the independent variable of vehicle driving speed and basic frequency of bridge, the approximate formulas of impact coefficient for simply supported beam bridge under three kinds of bridge deck grades are fitted by multivariate linear regression analysis. The formula is compared with the General Design Code for Highway Bridges and culverts in China. It is concluded that the calculation value of the impact coefficient of the 1: 1 code only takes into account the fundamental frequency is only suitable for a certain speed and the fundamental frequency range of a certain bridge deck class. The impact coefficient of a class A class bridge deck class B class is generally small when it is running at high speed, and the impact coefficient is larger at low speed. The impact coefficient of the bridge is large at low frequency, small at high frequency and small at C level, and the impact coefficient is larger at low frequency and low speed, and small at high frequency and high speed. 2 the magnitude of impact coefficient should be determined according to the design grade of bridge deck, design speed and bridge base frequency (length).
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441.3

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