Study on Calculation Method of Anti Overturning of Continuous Steel Box Girder

This paper describes the design of the Murray and Wolverine River rail bridges, two of the largest river crossings on British Columbia's Tumbler Ridge branch line. These unique railway bridges feature a single-cell, continuous steel box girder superstructure supported by pairs of steel delta legs. The top flange of the box girder is an orthotropic deck plate that is a part of the ballast containment trough. Stability of the delta legs is provided by posttensioning of their bases to the concrete substructure. Key words: rail bridge, steel box girder, steel delta legs, orthotropic deck, posttensioning.

The paper chose a three-span continuous steel box girder bridge with horizontal semicircular surface cracks as research object, and the cracks are non-through and unsymmetrical. Solving strain modal parameters of beams with cracks by means of the three-dimensional finite element theory, and applying continuous wavelet transform (CWT) to analyze the strain mode by Haar wavelet, then the position of the cracks could be identified by the maximum of wavelet coefficients. The validity of the method has been proved by numerical calculation and analysis. Some useful conclusions for continuous steel girders bridge have been drawn and it has been useful in surface flaw identification and diagnosis in structures.