Study On The Seismic Performance Of Extra-long Span Co Ntinuous Rigid Frame Bridge In High Seismic Area

In this paper,the seismic performance of the continuous rigid frame bridge in Ya'an Dadu River is studied.The modal analysis,response spectrum reaction and time history analysis of the bridge are carried out by using Midas / civil finite element analysis software.The bridge is designed in the form of artificial plastic hinge With a certain shock absorption effect,the main research content and conclusions are as follows:(1)The theory of the three methods used in the seismic analysis of bridge structures is introduced.The static method only considers the influence of seismic acceleration on the bridge structure,and the seismic calculation of the bridge has been rarely applied.The response spectrum method uses seismic power The problem is transformed into a static problem.The calculation results can obtain the maximum effect of the structure and can not be directly entered into the calculation of the plastic stage.It is only suitable for the calculation of the elastic phase.The time history analysis method can calculate the seismic response time curve and analyze the elasticity of the structure The internal force of the inelastic phase.(2)The response spectrum analysis of continuous rigid frame bridge in Ya'an Dadu River is carried out.The results show that the seismic analysis of bridge structure satisfies the accuracy requirement.Under the action of seismic load,the horizontal effect of the pier bottom section is larger than that of the vertical bridge,and the transverse bridge is larger than the bridge,and the vertical bridge is mainly supplied by the dead load.The vertical bridge displacement is less affected by the earthquake.The maximum force of the axial force,the shear force and the transverse direction of the transverse bridge are in the root section of the main beam,and the maximum bending moment of the bridge is in the middle cross section to satisfy the E2 earthquake Fortification standards.(3)The seismic wave selection rules are introduced,and the time-history analysis of the bridge is selected.The results show that the seismic response of the bridge is the smallest,the artificial wave is the largest,and the bridge pier The maximum bending moment of the main cross section of the main beam cross section occurs in the root section of the box girder,the vertical bridge is the largest in the cross section,the maximum the displacement value of the cross-section of the pier top section,the axial force and the bridge Which are larger than the other two directions.The bending moment of the three kinds of seismic waves is larger than that of the piers,and thebending wave is smaller than the ultimate bending moment of the section.The bridge has been destroyed under the artificial wave.(4)The dynamic and elasto-plastic analysis of the bridge was carried out by using the fiber model.The bridge pier bottom was bent over the top of the pier.Therefore,the artificial plastic hinge was set up and the seismic performance was analyzed.The results showed that Plastic bridge of the plastic bridge to meet the requirements of seismic precision;the main beam section and the piers pier top section of the horizontal displacement are increased,the main beam section of the internal force no significant change;new bridge pier bottom bending moment are greater than the original bridge,can effectively shorten the pier Yield time to ensure that the top of the pier first succumb to the pier at the end of the pile at the top of the artificial plastic hinge can play a certain role in shock absorption.(5)The results show that with the increase of the height difference of the pier,the internal force and displacement of the bridge to the high pier are higher than the height of the pier And the internal force of the lower pier increases with the height difference of the pier.With the increase of the piers,the shear force of the pier is gradually decreasing and the transverse direction of the bridge is increasing.The displacement of the bridge and the bridge is gradually increased,And the rate of change also increased.