Research On Seismic Energy Dissipation Performance Of Luding Dadu River Bridge Under The Action Of Near-Field Earthquake

In recent years,with the gradual formation of the highway network and the high-speed rail network in the southeast coastal areas of China,the development of traffic construction is gradually shifting to the west.When the traffic encounters a canyon or a river,the advantage of the bridge can be directly crossed,without constructing an winding mountain highway.In view of the complex mountainous terrain and canyons in the west,the bridge can truly cross the natural moat.The earthquakes in the western mountainous areas of China are frequent and intense.The fault zones are intricate,and there are many active fault zones.The road and railway transportation is inevitably adjacent or crossing the fault zone in the line selection.According to current research,the seismic response of structures near the fault zone will be greater,which brings great trouble to the seismic design of bridges in the western region.When such a site is encountered,the energy dissipation measures in the conventional design of the suspension bridge will not meet the seismic requirements.Therefore,various forms of vibration absorbing measures are required.The engineering object studied in this paper is the Dadu River Bridge in Luding,Sichuan.The bridge is sandwiched by several fault zones and is 1.5km away from the nearest fault zone.It is assumed that the bridge is in a field with obvious near-field effect,and four types of seismic waves including near-field pulse,near-field no pulse,hanging wall and far field are selected as excitations.The main research contents of this paper are as follows:1.The various enffects in the near-field earthquake are described,and the corresponding Chi-Chi seismic wave in Taiwan is selected according to its characteristics as the excitation input of the later research.The characteristics of near-field seismic waves and seismic wave determination methods for long-period structures are described from the aspects of peak acceleration,spectral characteristics and duration of action.2.The damping capacity performance of the buckling-restrained central buckle under the near-field earthquake is studied.By establishing six full-bridge models with different central buckles,the differences in dynamic characteristics are analyzed,and the response under near-field earthquakes and the energy-consuming ability of buckling-restrained.central buckles are calculated.3.Using the skeletal curve obtained from the experiment,a nonlinear full-bridge model is constructed by using nonlinear spring to simulate the Corrugated steel web composite beam.The superiority of the composite beam and the necessity of the ductility design of the beam are demonstrated.The adaptability of the corrugated steel web beam tower of the ductile design to the suspension bridge in the high-intensity near-field area is studied.4.The sensitivity of near-field seismic action to longitudinal viscous damper parameters is studied.By establishing 12 full-bridge models of damper parameters,the effects of various near-field vibrations on the response of the bridge are compared,it is found that the viscous damper is sensitive to the near-field pulsed seismic waves with high speed.