| In southwest China,due to the influence of topography and landform,many Bridges are built along hillsides,which leads to a large difference in the height of the pier in the cross bridge direction,resulting in the formation of irregular structure of the pier.Compared with regular pier of the same height,this type of pier of the structure is not uniform under the action of earthquake force,and the failure forms are diverse.In addition,compared with the conventional girder bridge with regular pier arrangement,the dynamic characteristics and seismic response of this type of girder bridge are more complex.However,there are few researches on this type of pier arrangement and i ts bridge at home and abroad.Based on this,with the background of "Construction of Civil Airport Viaduct in Nujiang Mountain Area of Yunnan Province",this paper carried out the seismic performance research of irregular three-column pier and the seismic response analysis of beam bridge.The main research contents and conclusions of this paper are as follows :(1)According to the actual situation of the background engineering and the size of the test site,a three-column scale model of irregular stacked pier was selected and made,which was composed of short,medium and high piers with large height difference,to carry out the pseudo-static test study.In the test process,the test phenomena of stacked pier under various loading systems were recorded,and the data obtained from the test were processed.The variation of hysteretic curve,skeleton curve,ductility coefficient,stiffness degradation curve and other performance indexes of the pier were obtained,and the failure characteristics and mechanical properties of this type of irregular three-column pier during earthquake were summarized.(2)At the same time,the scale model of single pier corresponding to the middle and high piers was made to carry out the pseudo-static test,and the test data were processed and analyzed,and the influence of pier height on the energy dissipation capacity,bearing capacity,ductility and other properties of column pier was obtained.(3)According to the test results and the material constitutive relationship,the finite element software of Open Sees and the fiber beam-column element based on the flexibility method are used to construct the numerical model of irregular three-column pier corresponding to the test.By changing the parameters of reinforcement ratio,diameter and height of low pier in the pier,the influence of pier parameters on the seismic performance of the pier is obtained.It provides a reference for the study of seismic performance of irregular stacked pier.(4)By using Midas Civil finite element softwa re,a beam bridge model with three columns of irregular piers was established.The dynamic characteristics,response spectrum and dynamic time history analysis were carried out to obtain the structural mechanical characteristics and seismic response result s of this kind of beam bridge,and the parts of this kind of bridge prone to earthquake damage were summarized.According to the analysis results,the optimization measures of setting transverse and longitudinal tie beams between the piers and replacing th e pier section with rectangular hollow section are adopted.Meanwhile,the response value of the optimized beam bridge is analyzed,and the feasibility of the above measures is discussed,which provides a reference for the seismic design of t he irregular pier girder bridge. |
