Static and Dynamic Performance Evaluation of Railway Through Continuous Steel Truss Bridge
After the completion of the Chengdu-Kunming Double Track Railway,some sections in old line will be merged into the double track and multiple-unit trains with a design speed of 160 km/h will be put into operation.In order to evaluate the service performance of typical bridges in the old line after the operation of multiple-unit trains,the static and dynamic performance of a 3×64 m continuous steel truss bridge was tested and evaluated by numerical simulation,on-site static and dynamic load tests.The results show that under static load,the maximum axial tensile and compressive stresses of the main truss member are 143.1 MPa and 175.4 MPa,respectively,both are less than the allowable stress of 240 MPa.The structure has sufficient strength and safety reserves.The ratio of deflection to span of the 34th,35th,and 36th spans are 1/1 756,1/1 940,and 1/1 732,respectively,which are less than the standard value of 1/1 250,indicating this bridge has the stiffness conditions for passing motor train unit.The maximum longitudinal displacement of the movable support under each load case is 3.195 mm,which is less than the allowable longitudinal displacement limit,indicating the movable support is in good working condition.Under the action of dynamic loads,the vibration mode and natural vibration frequency of the main girder have little difference with the verified results,and are smaller than the theoretical calculated values.All the vertical acceleration of the main girder span,transverse acceleration of the main girder span,transverse amplitude of the pier and transverse deformation of the movable support meet the requirements of the specifications,indicating the technical indicators of the main girder,piers and supports of the steel truss bridge meet the requirements of train passaging.
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