The Seismic Response Analysis And Research On The Submerged Floating Bridge

As a destructive and unpredictable natural disaster, the damage of the bridges caused by the earthquake would make huge loss of lives and property. Hence,a comprehensive and systematic study of the bridge seismic conduct is very necessary. At the present time, there is no unitive standard about the design of the long-span bridge seismic conduct, and the response analysis of the submerged floating reverse suspended cable sea-crossing bridges makes much more sense.The damage of the substructure and its base is the reason of bridge collapsing and hard to rehab after the earthquake. The damage of the bridge piers and its base is caused by the level force, which librates at the relatively weak section,in stantaneously and repeatly. Therefore, this thesis mostly takes the substructure as its study object.In this thesis the seismic response analysis of bridges at home and abroad are appraised involving seismic input, finite element modeling and response spectrum analysis, the liner time-history analysis, under the basic of the study situation and fundamental, takes the submerged floating reverse suspended cable sea-crossing bridges as the study back-information, outspreads the study from the seismic response of the substructure, including the following five aspects.This thesis establishes the finite element modle of the bidge substructure, mainly involving pier, platform, and pile foundation. It makes the static analysis of the structure, and it validates the rationality of the structure. Before the spectral analysis, it firstly makes the structural modle analysis, mostly considers the frequency, period,and vibration of the first ten orders modle. Bases on the analysis of the structural modle with the two dimensional seismic action, it takes the method of analysing response spectrum, studies the characterastic of structual seismic response, analyses the infection of the bridge structure caused by vertical earthquake force, mostly considers the load-settlement and the internal force situation of piers and the pile foundation. At the aspect of time-domain analysis, it makes the selection analysis for the input seismic waves, adopts liner time history analysis of the adjusted input seismic force, analyses the stress to the key section of the surstructure, mostly involves the internal force and the displacement of the belled pier and the hollow pier, the internal force and the displacement of the platform, the hollow pile foundation, the internal force of the belled pile foundation. And its results are compared with its response spectrum method results, and the results are all less than the results of the response spectrum analysis, it shows that the results of the response spectrum analysis is safer.According to《Cord for Seismic Design of Railway Engineering》, it calculates the seismic forece which the piers takes, and considers the situation with the water pressure, which has been compared with the situation without water. The period of the supported piers is obviously increased; the water pressure is more the the situation without water, we can not ignore its influence; Under the circumstances of the water, the basic top surface bending moment is obviously less than the situation without water. All the upwards results are caused by the influence of the seismic water pressure, which consequently changes the seismic response of piers.At the finality of this thesis, it makes a conclusion about the study work, presents some summing-ups from the study work, and points out some unresolved questions for the further study.