| In the construction project of urban modern highway bridges,the figure of the composite girder cable-stayed bridge is often seen.For example,there are two composite girder cable-stayed bridges in the Chongqing urban area that are currently under construction,and one is the Nanjimen Yangtze River Bridge.One is the Shuitu Jialing River Bridge.Whether it is the design or construction of a composite girder cable-stayed bridge,it is inseparable from the calculation and analysis of the bridge,and because the main girder of the composite girder cable-stayed bridge is composed of two materials,the difference between the main beam simulation method and a material is obvious,the selection of a reasonable main beam simulation method is the key to the calculation and analysis of the composite girder cable-stayed bridge.Based on the Fujiang Bridge,the three main beam model(M1),girder lattice model(M2)and the plate beam model(M3)were established by using Midas/Civil calculation software.The solid model(M4)was established by Midas/FEA.Through the analysis of the bridge state of the bridge,the static load of the load test,the static eccentric load and the self-vibration characteristics,the M1,M2 and M3 models are studied in the reasonable simulation of the main beam.The main contents of this article are as follows:(1)The development and structural characteristics of the composite girder cablestayed bridges at home and abroad,as well as the characteristics of the force,the research status of the different simulation modes of the main beam and the development of the load test are introduced.(2)Introduce the classification and finite element analysis steps of the calculation model of the cable-stayed bridge,and elaborate the basis for distinguishing the various models.(3)Briefly describe the project overview of the Fujiang Bridge,and detail the modeling methods of the three main beam model(M1),girder lattice model(M2),the plate beam model(M3)and the solid model(M4).The M1,M2 and M3 models in the bridge state are calculated and compared with the M4 internal force,cable force,stress and displacement.It can be seen that the M3 model is closer to the M4 model.(4)Introduce the static load test scheme,and calculate the strain,deflection and cable force increments for the M1,M2,and M3 models under the normal load and the eccentric load,using the loading conditions at the same position as the static load test.Compared with the measured values of the load test,it can be seen that the M2 model and the M3 model are basically the same,but the M3 model is more uniform.(5)Introduce the self-vibration characteristics test scheme,compare the frequency and vibration mode by analyzing the eigenvalues of the M1,M2,and M3 models,and verify the load test results.It can be seen that all three models can accurately calculate the first three-order vertical bending frequency of the main beam and the first-order side bending and longitudinal bending frequency of the main tower;the M1 model greatly increases the lateral direction of the main beam due to the rigid connection between the main beam and the bridge deck.The stiffness makes it impossible to calculate the torsional frequency of the main beam;the difference between the frequency calculation and the vibration mode of M2 and M3 is not obvious,and the frequency calculation results are larger than the measured values,and the vibration mode and the measured vibration mode are basically the same. |
