Seismic Response Analysis And Vibration Control Of Long-Span Bridge Under Multi-Support Excitation

Long-span bridges are vital elements of the lifeline engineering of modern societies. As one of the most devastating natural disaster, earthquakes always cause tremendous losses of life and property. In the event of an earthquake, failure or even damage of a bridge caused not only tremendous direct economic losses but also difficulties in the emergency response to the earthquake as well as in subsequent salvation and recovery activities.Multi-support excitation was a seismic input approach more suitable for long-span bridges than uniform excitation. Up to now long-span bridges' aseismic studies under multi-support excitation were mainly focused on theoretical analysis or numerical simulation; relative seismic design codes of bridge engineering had not considered multi-support excitation sufficiently for long-span bridges; and sufficient attention had not been given to studies in the bridge engineering world on seismic mitigation and isolation techniques which developed rapidly recently in housing industry.Model structure of a long-span arch bridge was experimental studied on the shaking table under multi-support excitation, seismic responses analyses of the arch bridge under multi-support excitation were numerical simulated with finite element method, calculation analysis of a long-span continuous girder bridge equipped with Lock-up devices was studied also in this paper. Several main works done are as follows.(1) Model structure of a long-span arch bridge was experimental studied on the shaking tables under multi-support excitation. Model structural performance under landscape orientation sinusoidal acceleration excitation in its natural frequency was obtained and influences of wave passage effect and attenuation effect on the model structural responses were concluded.(2) Dynamic responses analyses of the long-span arch bridge under multi-support excitation were numerical simulated using ANSYS which is a finite element software. The results were basically accordant with foregoing experimental data. Influences were analyzed of wave passage effect and attenuation effect on the long-span arch bridge's responses under multi-support excitation with actual seismic record. (3) An improved calculation model of Lock-up device was presented during structural seismic response analysis. The conception of effect judgment coefficient and a method to optimize the lock up velocity of Lock-up device using the coefficient was presented. An idea of further improving the calculation model was proposed also in this paper.