Study On Damage-Reduction Seismic System By Displacement Controlling Of Highway Girder Bridges

Bridge plays an extremely important role as the pivotal project of lifeline engineeringduring earthquake, the seismic performance of it will not only influence the disaster reliefbut also guarantee the post-disaster reconstruction and repair work, so it has vitalsignificance to make perfect seismic design for it.The thesis summed up the bridge damage in all previous earthquake, come to theconclusion that if the bridge hasn’t enough capacity to reply stronger earthquake than design,the foundation failure, or using improper design and construction method the bridge will bedamaged. Specific to the over-expected earthquake, the related parameters andcharacteristics of strong earthquake has been analyzed, the conclusion shows that somestrong earthquake have the characteristic of over-expected intensity, richer long-periodic infar-field, longer duration and clustery scale. The development of seismic design for bridgeand the characteristics of the design method have been reviewed, the damage-reductionseismic design which belongs to the performance-based seismic design has been elaboratedescribed, the usage and study situation of damage-reduction seismic design in the bridgeengineering has been illustrated.Combined with the damage-reduction seismic design, the damage-reduction seismicsystem has been defined. It was an aggregate composed with related damage-reductioncomponents, which making bridge to achieve the seismic capability and integral securitywith minimum total cost. From the standpoint of damage-reduction method, it was beenclassified to be the energy consuming type and the displacement controlling type. The latterwas the method been choose in the paper.The time history analysis method was been used to analyse the seismic response of thebridge, and than the necessity of performance-based seismic design was been proposed tothe large displacement under medium earthquakes and large earthquakes. Combined withthe relevant regulations and existing research results of damage-reduction seismiccomponents such as bearing, expansion equipment, supporting length, limiting device andunseating prevention device, the parameter design and effect analysis was been used. The result shows that setting up reasonable damage-reduction components can decrease the largedisplacement under the earthquake effectively, prevent the failure of bearings and collision,and increase the integrity of the structure.Comparative analyzed the seismic response of bridges and actuating law ofdamage-reduction components with different composition, it shows that the more perfectthe configuration was been used the better effect the displacement been reduced. All thecomponents could exert their function requirement and protect each other, the designrequirement and displacement scopes of them were been provided then. The ensemble useof damage-reduction system could decrease the displacement of bridge and prevent thefailure of bearings and collision effectively. Then strong earthquake and earthquakesequence were been used to prove the effect of the damage-reduction system and actuatinglaw of the components, it was showed that the damage-reduction system could decrease thedisplacement of bridge under over-expected earthquake, but the components were probablyto be damaged.