Supported Beam Bridge Seismic Performance Of The Dynamic Method Evaluation Studies

Effective method should be adopted for a let of simply supported existing bridges to assess comprehensively their real structural seismic performance in order to study the next technical project. Based on the dynamic behavior of the model bridge, the new method of assessing the structural seismic performance is explored in dynamics. The longitudinal and transversal seismic vibration equations of the simply supported bridge with infinite spans and approximate formulas for their basic natural periods and modal participate coefficients are theoretically derived by the LaGrange Equation. The method of computing the longitudinal and transversal seismic forces based on the structural ductility is given. In the basic shape function, the deformations are divided into three parts, i.e. the elastic deformation caused by a unit horizontal force at the top of the piers, the deformations caused by the rotation and translation of the foundation. Both the impulse excitation method and the stable sine-wave excitation method are experimentally adopted for the mode analysis of the model bridge, the basic parameters including the redundant dynamic characteristics are decomposed and the longitudinal and transversal se smic performance of the simply supported bridge is assessed on the basis of the dynamic parameters.The paper is a practical application of dynamic method in assessing bridge seismic performance, and we hope that it can be referenced for revising the design specification of precautions against earthquake.