Multi-point Seismic Response Excitations Analysis Method Research For Long-Span Structure

Bridges are vital elements of the economic functioning 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 can pose a significant life hazard, and cause difficulties in the emergency response to the earthquake as well as in subsequent recovery activities.Response spectrum method used in the existing bridge design specifications, only considers the impact of the single-point excitation, however, in the actual earthquake, seismic ground motions of all supports of the bridge are different due to the difference in the arrival times of seismic waves at different stations, the loss of coherency of the motions due to reflections and refractions of the waves in the heterogeneous medium of the ground, as well as due to the difference in the manner of superposition of waves arriving from an extended source at various stations; and the difference in the local soil condition at each station and the manner in which they influence the amplitude and frequency content of the bedrock motion.In this thesis, taking one long span continuous rigid-frame bridge as an example, based on the basic theory of the seismic response analysis, multi-point response spectrum and single-point response spectrum analysis the bridge. The main content in this thesis includes:1. Set up method of multi-point seismic response spectrum input.2. Set up analysis method of structural natural vibration property, corresponding to multi-point seismic response spectrum input.3. Then the engineering examples are analyzed, accurate finite element model is established, the rigid frame bridge is dynamic analyzed with multi-point seismic response spectrum analysis method proposed in the paper, compared to the traditional single-point seismic response spectrum analysis method, the analysis result proofed the rationality and feasibility of the theories proposed in the paper.It is expected to give some references for practical seismic design of long span structure.