考虑剪切效应的混凝土桥墩撞击动态力学特性研究

Research on the Impact Dynamic Mechanics Characteristic of Concrete Bridge Pier Considering Shear Effect

为研究桥墩撞击剪切动力响应问题,基于Hamilton原理,将剪切变形引入碰撞体系偏微分方程中,考虑材料的动态力学性能,通过Laplace变换和Matlab软件求解,建立了考虑剪切效应的钢筋混凝土和钢骨混凝土桥墩动态剪力方程和动态弯矩方程,揭示了桥墩撞击动力响应受剪切效应影响的力学特征。理论计算和试验结果对比表明:剪切变形对桥墩试件峰值弯矩和峰值主拉应力的平均影响分别为8.82%和18.83%,剪切效应对桥墩撞击动力响应的影响较大,不可忽略。在桥墩抗撞强度设计中,不仅需要验算桥墩最大弯矩截面的拉应力,还应验算墩底的主拉应力,以体现剪切效应对桥墩撞击剪切破坏的影响,保证桥墩结构的安全。

In order to research the shear dynamic response of pier under impact load, the shear deformation is introduced into the partial differential equation of collision system based on the Hamilton principle, considering the dynamic mechanical properties of materials. The dynamic shear force and ben- ding moment equations of reinforced and steel reinforced concrete bridge piers are established considering shear effect, applying the Laplace transformation and the Matlab software. The mechanics characteristics of the impact dynamic response of piers, influenced by shear effect, are revealed in these equations. Through comparison of theoretical calculation and experimental results, it is showed that the average in- fluence of shear deformation on the peak of bending moment and peak of principal tensile stress is 8.82% and 18.83% , respectively. The shear effect has greater influence on impact dynamic response of pier, which can not be neglected. The design of impact resistant strength of pier needs not only checking the tensile stress of maximum bending moment section of pier, but also checking the principal tensile stress of flexure - shear region of pier, reflecting the influence of shear effect on impact shear failure of pier, in order to ensure safety of bridge structures.