Research On Vibration Response Of A Long-Span Stayed-Cable Bridge Under Earthquake Excitation Based On Energy Method

In recent years, energy-based aseismic design is a popular research project in the field of earthquake engineering in the world. This paper applies energy method for analyzing vibration response under earthquake excitation, and deals with the energy response of single degree of freedom structure and long-span bridge structure by utilzing the dynamical time-history analysis method.Firstly, based on the vibration differential equation, the energy response equation of a structure under the earthquake excitation is established. Energy response analysis program is compiled using FORTRAN language, and it is utilzed to analyze the energy response of single-degree of freedom under the earthquake excitation. The result shows that the seismic parameters (amplitude, frequency spectrum and lasting time) and the structural dynamic parameters (damping ratio, periods of free vibration and factor of elastic limit) play important roles in the total structural aseismic input energy and its distribution between damping energy and hysteretic dissipated energy, there have: 1) With the increasing of the ground motion amplitude, the total input energy increases rapidly, and the ratio of hysteretic dissipated energy becomes larger; 2) When the damping ratio increasing, the ratio of hysteretic dissipated energy decreases, but the total input energy remains almost the same value.Secondly, this paper takes the north cable-stayed bridge of Runyang bridge as a research object, and applying ANSYS general FEM software to set up the FEM model of this cable-stayed bridge structure. The special dynamical characteristics of this bridge are investigated, including the natural frequency, the features of natural models and so on. Tianjin wave, Taft wave and EI-centro wave are chosen as the input ground motion, and time-history analysis is adopted to acquire the structure's time-history curve of energy distribution and vibration features. The result show that the damping energy varies from each other between the different ground motion records. It also shows that the displacement response of the structure differs while the frequency of structure vibration is close to each other, and the structure will vibrate in the 5th (vertical) and 7th (horizontal) mode shape in detail.Finally, this paper applies TMD to control the vibration response of the cable-staged bridge under earthquake excitation, the model of which is set up based on TMD. The effect of TMD parameters (mass, natural frequency, damping ratio) on controlling the cable-staged bridge structure response (energy, displacement, force) is analyzed. The results indicate that the TMD can decrease the energy dissipation attribute to major...