FORMULAS FOR FUNDAMENTAL FREQUENCY OF BRIDGE PIERS BY ENERGY PRINCIPLE

摘要

The approximate formulas of the fundamental natural frequency for bridge piers with shallow, pile as well as sunk shaft foundation are derived by using the Rayleigh Method. In the shape function, the total deformations of bridge piers are divided into three parts: i.e. the elastic deformation of the pier body, the two kinds of rigid displacements caused by translation and rotation of the foundation. The elastic deformation of the pier body is assumed to be a tri-polynomial function and the rigid displacement is assumed to be a linear function. The translation, the rotation and the coupled springs representing the foundation deformation are considered in derivation. The calculation formulas presented in this paper are clear in concept, simple in computation and high in precision. The formulas are not only adaptable to bridge piers with different kinds of foundation, but also suitable to the chimney and the water tower.