Method for determining fundamental frequency of railway variable-cross-section continuous beam bridge

Abstract

The invention discloses a method for determining the fundamental frequency of a railway variable cross-section continuous beam bridge. The method comprises the following steps: (1) collecting structural data of the railway variable cross-section continuous beam bridge, wherein the structural data comprises the concrete elasticity modulus of the structure, the calculated span of the structure, theinertia moment of the midspan cross section of the structure and the weight per unit length of the midspan of the structure; 2) calculating the fundamental frequency of the structure according to General Specifications for Highway Bridge and Duct Design; 3) establishing a fundamental frequency calculation model of the railway variable cross-section continuous beam bridge; and 4) obtaining a finalfundamental frequency calculation result of the railway variable cross-section continuous beam bridge according to the fundamental frequency model calculated in the step 2) and the calculation model calculated in the step 3). The method is suitable for variable cross-section continuous beam bridges with various spans, the calculated fundamental frequency result is more accurate, and the relative error is reduced to 3% or below from the maximum 20%. By using the method provided by the invention, the time for a designer to obtain the accurate fundamental frequency can be saved.

Description

technical field [0001] The invention relates to the design of railway bridges, in particular to a method for determining the fundamental frequency of railway variable-section continuous beam bridges. Background technique [0002] With the development of high-speed railways, railway bridges have developed rapidly, and variable-section continuous girder bridges have been widely used due to their strong spanning capacity, increased clearance under bridges, and mature construction techniques. For variable cross-section continuous girder bridges, the fundamental frequency plays an important role in structural dynamic response, seismic design, and calculation of impact coefficients, but the corresponding codes for railway bridges do not provide the calculation formula for variable cross-section continuous girder bridge fundamental frequency. The fundamental frequency calculation formula in the "General Code for Design of Highway Bridges and Culverts" (JTG D60-2015) has a large err...

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Problems solved by technology

For variable cross-section continuous girder bridges, the fundamental frequency plays an important role in structural dynamic response, seismic design, and calculation of impact coefficients, but the corresponding codes for railway bridges do not provide the calculation formula for variable cross-section continuous girder bridge fundamental frequency. The fundamental frequency calculation formula in the "General Code for Design of Highway Bridges and Culverts" (JTG D60-2015) has a large error in the fundamental frequency calculation formula. When the span is not greater than 56m, the error is small, but when the span is 60m and In the above cases, the error is relatively large, reaching a maximum of 21.61%, and the reliability of the calculation of the fundamental frequency of the railway variable-section continuous girder bridge is relatively small. At the same time, the designer obtains the fundamental frequency of the variable-section continuous girder bridge by establishing a finite element model. Therefore, a A reliable method for determining the fundamental frequency of railway variable cross-section continuous girder bridges is necessary

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