Earthquake Response Analysis Of Nanjing Dashengguan High-speed Railway Bridge Across Yangtze River

The Nanjing Dashengguan Bridge is one of the most important part of the Beijing-Shanghai high speed railway.The bridge is a long span bridge across the Yangtze River,and many new materials and new construction technologies are used in the design.The character of the bridge is long span,long suspension and low damping.The main span of the bridge is composed of 108+192+336+336+192+108m continuous steel truss arch structure,and the side spans are composed of 2×84m continuous truss girders.The steel consumption of the whole structure is about 80,000 tons.The deck of bridge is 41.6m in width,which carries six tracks,including two tracks for high-speed trains of 300 km/h,two tracks for conventional trains of 120km/h and 200 km/h and two tracks for metro-trains of 80km/h.The metro tracks are designed at the two side cantilevers with the width of 5.8m,the central line of the track is 3.25m from outside of the arch ribs.Firstly,the outline and technical indexes of the Dashengguan Bridge are introduced. Then the key points in the course of the structure modeling by using the software of ANSYS and MIDAS are summarized.Secondly,the dynamic properties indexes of the main bridge are calculated.The first 15 frequencies and cycle time and the first 10 modal shapes of the main bridge are shown in graphs and tables.When the calculation of the basic dynamic properties has been completed,the spectrum analysis is taken.The response of the displacement and internal force in horizontal,lateral and vertical directions are received after calculation.Next,the time history response of the bridge in the association of"Ex+0.3Ez" and "Ey+0.3Ez" of earthquake wave "El Centro" is analyzed,and the displacement and internal force response of the bridge in the association of"Ex+0.3Ez" and "Ey+0.3Ez" of earthquake wave "El Centro" according to the are analyzed.Then the two different simulation methods of the pile stiffness are compared.As the character of the long span structure,the response of the main bridge considering the traveling earthquake wave effect should be calculated.The displacement and internal force response of the main bridge in the "El Centro" earthquake with the speed of 300m/s,500m/s,1000m/s and 2000m/s are compared with the final result obtained by the spectrum analysis and the normal time history analysis.Finally,the dynamic properties of the 2×84m span bridge connected to the main bridge is calculated by using the software of MIDAS,and the time history response of the bridge in the earthquake wave association of "Ex+0.3Ey+0.3Ez" according to the is analyzed.