| The concrete-filled steel pipe bridge was widely used because of its unique advantages.The dynamic characteristics of the bridge structure influence the safety and comfort of driving with the development of the arch bridge,the increase in tensile width and the speed of the train.The 128 m CFST Tied Arch Bridge of Yinchuan South Bridge on Yinchuan Wuhan Passenger Line as a research background,the natural vibration characteristics and the dynamic response of the bow bridges under traction load are analysed and calculated.Close The rodent element model introduced by the Midas-Finite-Element-Software is Comparison of the Midas Finite Element software-set solid model and analyze the dryer cable power.The calculation results are compared with the original model of Midas Finite Elements software,and the sustainer cable force is based on the method of rigid arm connection The main content are:(1)In this article Midas civil is used to establish the finite element simulation model of the bound arc bridges and the natural vibration characteristics of the bound arc bridges to to analyze.show results,that the main vibration forms of the arc bridge vertical and torsion vibrations are.The non-scheduled vibration of the arc strip is the most important low vibration mode,and the rolling vibration of the arc strip is the most important vibration arm Mode.E is determined,that the vibration of the beam occurs mainly in vertical plane and causes the vibration of the entire bridge by the vibration of the beam from the the shape of the mode can be seen that the stiffness of the beam is relatively small.(2)In the process of rise span ratio increasing from 1 / 7 to 1 / 3,the former four modes are discussed.Compared with the transverse vibration(the first and third modes),it is found that the transverse vibration is out of plane symmetrical vibration of arch rib,and the natural frequency gradually decreases;compared with the vertical vibration(the second and fourth modes),The results show that the transverse oscillation is symmetrical and the natural frequency is gradually decreasing.Keeping other parameters of arch bridge unchanged,the change of natural frequency is very small whether the diameter of arch rib section increases or decreases.By changing the stiffness of the concrete in the arch rib tube,it is found that the change of the natural frequency is very small.(3)By reducing the k-brace in the basic model,the natural frequency changes obviously.After changing the cross brace form from K-shape to H-shape,the change of natural frequency is more obvious.When the form of cross brace changes from K-shape to H-shape,the natural vibration frequency decreases correspondingly,which is the result of increasing the transverse mass of the arch and improving the transverse overall stiffness of the arch,especially the through tied arch bridge.Due to the improvement of the mass and center of gravity of the arch,the influence of transverse seismic force on the arch is becoming greater and greater.Therefore,in practical engineering,it is necessary to comprehensively consider the transverse seismic force The effect of stability and lateral seismic force on the transverse bracing should not be set up arbitrarily.(4)When the moving train passes through the arch bridge at 250km/h to 350km/h,the internal force values at 1/2,1/4 and 3/4 of the arch ribs of the arch bridge are analyzed and calculated.The calculated internal force responses show a trend of overall increase,which indicates that the arch ribs have obvious dynamic effect with the increase of the train speed,and the greater the speed,the more obvious the dynamic effect is.(5)The vibration reaction of the arc bridges is based on the aspects of the rigidity of the bridge,the vertical mean voltage increase of the distance beam and the transverse acceleration of the mean span width of The calculation results show that under the influence of the high-speed rail load,when the train is running at the speed of 250km/h,275km/h,300km/h,325km/h and 350km/h,according to the relevant national and foreign standards for dynamic performance assessment of the railway bridge,the construction of the bridge is possible and the vertical deflection limit,the cross-reflection limit,the vertical acceleration and the cross-acceleration limit of the bridge are much lower than the specified limit indicates that the bridge structure is safe when the train is running within the speed range of250km/h～350km/h.(6)By comparing and analyzing the static cable force values of the original bar system element model,On the joint of the rib and the connecting bar the model of the rigid arm buckle and the model of the fixed element are used,it is found that when the rigid arm connection is applied at the connection of arch rib and tie beam of the original bar system element model,the cable force value of the short rod is greatly reduced,while the cable force value of the suspender at other parts is no different And the cable force calculated by each suspender is basically consistent with that obtained by solid element model.(7)Three models were used to analyze the dynamic coefficients of the internal forces of the hanger rods when the moving train load passed through the tied-arch bridge at a speed of250km/h to 350km/h.It was found that the dynamic coefficients of the internal forces of the hanger rods of the three models all increased with the increase of the speed.The numerical value of internal force dynamic system calculated by the original string-system element model is larger than that obtained by the other two models.The numerical results obtained by the link element model and the solid element model are basically close to each other.Therefore,we can suggest that in the detection and design of tied arch bridge,when using Midas Civil to build the model,except other parameters remain unchanged,rigid arm connection should be applied to the arch foot and the short suspender,so as to be more close to the actual situation,or using Midas FEA to build the solid element model and solve directly. |
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