【作者】 刘云；

【导师】 钱振东；

【作者基本信息】 东南大学 ， 道路与铁道工程， 2006， 硕士

【摘要】 在车辆动荷载的反复作用下大跨径斜拉桥桥面铺装层产生了各种破坏,尤其以裂缝类病害为主,以往的桥面铺装的静力学计算结果不能准确地解释铺装层的破坏原因,本文从动力学的角度对铺装层体系进行了受力分析,以期能更好地解释铺装层开裂破坏的特性。本文首先利用有限元软件建立了大跨径斜拉桥常见的正交异性板钢桥面铺装体系模型,通过模态分析,得到局部模型各阶振型的频率和振动特点,分析了铺装层的模量和厚度对局部模型固有频率的影响。其次采用动力有限元计算方法分析了移动恒载作用下的铺装层动力响应变化规律。计算中将车辆荷载简化为垂直均布荷载,考虑冲击系数,分析结果表明跨中位置为最不利受力位置,在最不利位置处,竖向位移和最大横向拉应力都将达到峰值;车速、铺装结构阻尼的变化对铺装层表面的竖向位移和最大横向拉应力的影响不大;随着车速、阻尼比的增加,竖向位移和最大横向拉应力都有减小的趋势。最后利用功率谱密度函数模拟铺装层表面的不平整特性,根据车辆振动方程模拟随机动荷载,分析了大跨径斜拉桥钢桥面铺装层在随机动荷载作用下的响应变化规律。计算结果表明考虑不平整度情况下铺装层的竖向位移和最大横向拉应力的峰值分别是只考虑冲击系数时的1.35倍和1.34倍。考虑桥面铺装层表面不平整特性因素导致的铺装层动力响应幅值增加较大,此结论对桥面施工及维护提出了更高的要求,研究同时表明在桥面铺装层的动力分析中车轮荷载只考虑冲击系数的作用是偏低的。本文研究成果可为复合梁疲劳试验的应力应变等效方法提供动力学指标,为研究铺装层材料以及铺装层结构提供理论参考。更多还原

【Abstract】 Cracking deterioration has become the main problem in deck pavement of long-span cable-stayed bridge under the dynamic vehicle load. The result of the static analysis of deck pavement can not exactly illuminate the crack failure of deck pavement, so the dynamic response of deck pavement under dynamic vehicle load was researched in this paper to explain the cracking deterioration better.Firstly, finite element software was used to establish the orthotropic steel deck pavement model which is usually used in long-span cable-stayed bridge. Through the Modality analysis, the vibration characteristics were researched, and the influence of the thickness and modulus of pavement on Natural Frequency of the model was discussed.Secondly, by using time function and time step, the vehicle load was set to be wheel load which has the invariable value, and the impact coefficient was considered only in the load. The result of dynamic analysis shows that the middle place of the model is the worst place, whereas the vertical displacement and the transverse maximum tensile stress would come to its peak value in the worst place. The change of the vehicles’speed together with the change of the damp slightly affects the result. The value of the vertical displacement and the transverse maximum tensile stress will decrease when increasing the speed of the vehicles or the damping ratio.At last, the irregularity of the pavement’s surface was simulated by using the power spectrum density function and the random load was calculated according to the vehicle vibrating equation, the dynamic response of deck pavement under random dynamic load was calculated by using FEM. The result of dynamic analysis shows that the vertical displacement is 1.35 times as much as the vertical displacement when the impact coefficient is taken into account only, and the transverse maximum tensile stress is 1.34 times as much as the transverse maximum tensile stress when the impact coefficient is taken into account only. The increase of the dynamic response of pavement considering the irregularity is bigger than the dynamic response of pavement considering the impact coefficient only. The result puts a higher request in the pavement construction and maintenance, and also presents that it is not enough to consider the impact coefficient only in the vehicle load.The conclusions of this dissertation can provide kinetics parameters for the method of stress/strain equivalence of fatigue experiment and theoretical reference for the analysis of the material and structure of deck pavement.更多还原