| In southwest China for a Super three-span continuous rigid frame bridge theactual engineering background, its in accordance with the dynamic characteristicsanalysis, response spectrum analysis and time history analysis, analysis of the seismicperformance. The main contents are as follows:(1) Refer to the domestic and foreign literature on the rigid frame bridge,summarize the structural characteristics of this type of brid ge, the development ofhistory, damage characteristics, seismic design method and research Status.(2) Using the MIDAS software to establish a bridge of two finite elementanalysis model, the pier bottom consolidation model A and pile-soil effect mold typeB, the dynamic characteristics of the first model for analysis. The analysis showed:Model A’fundamental frequency (0.330316Hz) smaller frequency illustrate theflexibility of the bridge system, will have a significant deformation under seismicaction. Bridge piers higher horizontal direction stiffness of the entire system is small,the bridge is more likely to occur when receiving an external force, horizontal andvertical swing. Lateral stiffness relative to the longitudinal stiffness weaker.(3) In accordance with the seismic fortification intensity of the Model A andModel B response spectrum analysis, the comparison between the results of theanalysis, pointed out that the pile-soil effects of such bridge seismic design.Earthquake, the large-span continuous rigid frame bridge seismic response to thedirection of the input response spectrum, you can use the pier flexible to adapt to theearthquake. Model A model to calculate the result safer, but it will cause materialwaste, is not conducive to economic design; Model B calculation results favorable tothe pier, but the main beam. (4) To select the appropriate seismic waves into the multi-dimensionaltime-history analysis of the bridge, and analysis of the limitations of the responsespectrum analysis. Seismic waves after the selection of AM El-Centro wave, Taftwave, Lanzhou wave, during single point excitation, the spectral characteristics of thefirst two waves of more appropriate model of the bridge. Response spectrum analysismethod is accurate enough for higher modes reaction was not significant bridgestructure, but for Flexibility larger structures, the response spectrum analysis methodis conservative. Vertical ground motion input so that the bridge piers axial force,across the vertical displacement increases, considering vertical ground motion input isvery necessary in the seismic design of long-span bridges.(5) To consider traveling wave effect, the same seismic waves at differentvelocity input bridge the analysis of non-uniform excitation, the laws of the seismicresponse of wave velocity. Analysis found that the bridge is more sensitive to theeffects of traveling wave. With respect to uniform excitation from the earthquakecenter pier moving closer to a slight increase in the distant pier displacementdecreases; with the input wave velocity increases gradually diminishing travelingwave effect on the bridge, when the input velocity is large enough pier seismicresponse and uniform excitation of the results of the analysis is essentially the same.Uniform seismic analysis of the seismic design for bridge piers is accurate enough,but for the main beam section is no longer accurate. Structure design-span rigidframe bridge should attach importance to the traveling wave effect... |
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