风载作用下JQ900A型架桥机结构动态响应特性研究

Study on Dynamic Response Characteristics of JQ900A Bridge Erecting Machine under Wind Load

鉴于架桥机发生前倾或侧翻事故较多,对其在风载作用下的结构动态响应进行了研究。首先构建了具有指数风廓线和Kaimal脉动风功率谱特性的风场模型,并采用FFT技术得到自然风风载时程曲线;其次,针对风载情况下JQ900A型架桥机架桥的4种危险工况,建立了架桥机的有限元模型,通过静力学分析进一步确定危险工况下整机的危险部位;最终将风载作为输入条件,对架桥机进行瞬态动力学分析,研究其危险部位的位移及应力特性。结果表明:轴线方向风载对架桥机结构动态响应影响最大,并且架桥机其他方向上稳定性和自身阻尼作用更强,因此更容易发生前倾事故。当处于半载和落梁工况时,主梁和前支腿的动态响应尤为明显,是实时监测和结构改进的重点。

Considering that there are many forward tilt or rollover accidents of bridge erecting machines,the dynamic response characteristics of the structure under wind load is studied in this paper.Firstly,a wind field model with exponential wind speed profile and Kaimal spectrum of stochastic fluctuating wind is constructed,and the pressure-time curve of natural wind is obtained by fast Fourier transform(FFT)method.Secondly,according to the four representative dangerous working conditions under wind load of the JQ900A bridge erecting machine,a finite element model of the bridge erecting machine is established,and the dangerous parts of the whole machine under dangerous working conditions are further determined through static analysis.Eventually the transient dynamic analysis of the bridge erecting machine is carried out with the wind load as the input condition,the displacement and stress characteristics of dangerous parts are studied.Studies prove that the axis wind load produces major effects,because the stability and self-damping are stronger in other directions,so it is more prone to forward tilt accidents.The dynamic response of the main beam and the front leg is especially obvious when the beam is half-loaded and falling,which will be the focus of real-time monitoring and structural improvement.