【作者】 李礼；

【导师】 罗松南；

【作者基本信息】 湖南大学 ， 工程力学， 2009， 硕士

【摘要】 近年来,我国不断加大对基础设施的建设,主要集中在公路,铁路以及桥梁的建设。由于建设场地地形、地貌复杂,尤其是边缘山区和西部地区,在崇山峻岭中需要跨越深沟峡谷,经常会用到高桥墩,而且各桥墩高度差异不可避免,这将给桥梁的施工和设计带来许多难题。高桥墩作为轴向受力构件,由于受到自重,上部的冲击荷载以及地震的影响,稳定性问题是该类构件要考虑的首要问题,因此在冲击荷载作用下的高桥墩的动力特性分析及动力稳定性的研究非常重要。本文主要考虑剪切变形、几何非线性和本构非线性,建立高桥墩在冲击荷载作用下的非线性动力学基本方程式;通过位移形函数假设,采用Galerkin积分方法得到了时间变率的动力学控制方程;利用四阶Runge- Kutta法进行数值求解。为工程应用提供理论的依据。主要内容如下:(1)介绍高桥墩屈曲问题的基本概况、桥墩屈曲问题的基本理论。根据柱的屈曲特征,考虑几何非线性和物理非线性,建立高桥墩屈曲问题的控制方程。详述龙格-库塔方法的基本原理、程序设计方案以及伽辽金方法的基本理论。(2)讨论混凝土高桥墩在两端简支情况下受到三角形冲击荷载和矩形冲击荷载作用时的非线性动力屈曲问题,给出冲击荷载作用下的位移响应曲线,描述了高桥墩的动力屈曲路径,分析各种几何参数和荷载参数对动力屈曲的影响。(3)研究混凝土高桥墩在一端固支一端简支情况下受到三角形冲击荷载和矩形冲击荷载作用时的非线性动力屈曲问题,得到了与两端简支情况下相似的屈曲规律,并比较了与高桥墩在两端简支情况下屈曲问题的差异,为工程实际提供有价值的依据。(4)考虑双线性本构模型时,求解混凝土高桥墩在两端简支情况下受到三角形冲击荷载和矩形冲击荷载作用时的非线性动力屈曲问题,得到了位移响应曲线,冲击临界荷载,并分析考虑塑性变形时对高桥墩稳定性的影响。更多还原

【Abstract】 Resent years, our country increased constructions of the fundamental establishm- ent constantly, mainly in the road, the railway and the bridge. Due to the complication and oddity of the terrain, the high piers are always used in the engineering when the construction through in the high mountains and cangons, especially in the remote mountain areas and the western. Many difficulties can be proposed in the construction and design of the pier.As the high pier mainly subjecting to axial load, the stability problem is the important problem of the high pier under the impact on the top or the influence of the earthquake. So the research of the dynamic characterity and the dynamic stability of the high pier is of great importance when under the impact load. In this paper, includ- ing the shear deformation and large deformation, the basic nonlinear dynamic equations are established. Then the time-dependent equations of the high pier under the impact are founded by using the Galerkin method when deflection shape functions assumption applied. The result to this problem is obtained by using the four-order Runge- Kutta method. The theory is offered for the engineering application. The following contents are mainly discussed in this paper.(1) The basic conspectus and theory of the buckling of the high pier is introduced firstly. According to the buckling property of the pier, the control equations of the buckling of the high pier is established including both the geometric and physical nonlinearity. The Runge- Kutta method, the program design and the basic theory of the Galerkin method are introduced in details in this paper.(2) Under the triangle-shape impact and rectangle-shape impact load, the dynamic buckling of the concrete high pier with two endpoints simply supported are investigated respectively. The deflection curves of the pier under impact load are presented. The dynamic buckling routes are depicted. The influence of the geometric parameters and load parameters on the dynamic buckling of the pier are discussed.(3) Under the triangle-shape impact and rectangle-shape impact load, the dynamic buckling of the concrete high pier with one endpoint simply supported and the other fixed are investigated respectively. The similar dynamic bulking rule to both the two endpoints are simply supported are observed, and the differences of the buckling route form the two endpoints when simply supported are compered. Some valuable references is presents for the engineering practice. (4) Under the triangle-shape impact and rectangle-shape impact load, the dynamic buckling of the concrete high pier with two endpoints simply supported is analyzed as the bi-linearity constitutive model is adopted. The displacement response curve of high pier under the impact load are present. The influence of the plastic deformation on stability of the high pier is analysed.更多还原