Research On Seismic Performance And Reinforcement Effect Of The Bridge Which Under Strong Earthquake

As a transportation hub project, the bridge once severely damaged during theearthquake will cause huge losses.Therefore, It is necessary to evaluate and analyse theseismic performance of the existing bridges at the right moment, which can help peopleto find out the weak part of the seismic performance and provide the basis for the thereasonable reinforcement measures. Accordingly, Based on a existing bridge of Japan,using the TDAPⅢ finite element software, the calcution of the bridge seismic responsewas carried on in the paper. By analyzing the response result, the conclusion that theseismic performance of the piers of this bridge is not enough and need to reinforce canbe judged. Then, reasonable reinforcement measure was raised. In order to disscuss thethe seismic performance of the bridge which was reinforced is enough or not andevaluate the reinforcement effect, the calcution of this bridge was conducted again afterthe piers were reinforced. The main research contents are as follows:Summarizing the types and the mechanisation of the bridge damage which causedby the earhequake. Discussing the present situation of the research for the reinforcementtechnology of the bridge. By comparing advantages and disadvantages of severalseismic analysis methods which were commonly used, the time-history analysis waschoosed as the research method in this thesis.Considering the nonlinearity of piers, the large finite element analysis softwareTDAPⅢ was used to modeling the3D model of the bridge on various finite elements.Based on the established finite element model, the study on dynamic characteristics ofthe bridge was carried out. Rayleigh damping was employed to establish the dampingmatrix and the problem that how to determine the damping coefficient was discussed. Itpointed out that the vibration mode and effective mass ratio shoud be considered whenthe modes are selected.Seismic wave was input and the seismic response of the bridge was carried out.According to the analysis of the internal force of the piers、bending moment-angelhysteretic curve of the plastic hinge of piers and the time curve of the diaplacement ofthe top point of the piers, the following conclusion can be obtained:bending failure orshearing-destroy was happened to parts of piers,the angel of the plastic hinge of somepiers were passed the allowable value, the ductility of piers was not fully exerted, somereinforcement measures should be carried out to ensure the seismic performance of this bridge.According to the damage situation, the method of concrete outsourcing for thebridge piers was proposed, and then the seismic response of the bridge was carried outagain. The conclusion is as follows: the internal force of all the strengthened piers wereunder the allowable value, no damage occured; the angel of the plastic hinge of all pierswere under the allowable value too, the displacement of the top point of the pierswhich reinforced was slowed sharply compare to the original piers, the ductility of pierswas improved in a degree.Above all, the effect of this reinforcement measure is good,can provide reliable reference for similar project.