A simplified method for the quick assessment of bridge decks

This paper presents a quick but accurate method for the assessment of bending moments and deflections in simply supported bridge decks by the use of distribution coefficients under the action of Load Model 1 (LM1) as per, EN 1991-Part 2: Traffic loads on bridges. The current work builds on previous research presented by the author and Ryall M. J. [1] as the assessment of stress resultants and displacements in bridge decks by the use of distribution coefficients.

The method named as D-type is based in the assumption that the bridge deck can be analysed as a continuum or semi-continuum and can be defined by the use of characterizing parameters α and θ which model the flexural and torsional rigidities of the deck and they are unique for a particular orthotropic deck. The loads are analysed in harmonic components and the width of the deck and the distance of the load from the edge of the deck are considered as controlling factors. A simple distribution factor D is defined, relating the maximum overall longitudinal bending moment due to the design vehicle load to the peak of the transverse distribution across the deck.

A computer program has been developed and used to carry out a parametric study resulting in distribution coefficient values for a wide range a bridge decks due to a variety of live loading specifications. The results can be presented in the form of tables or charts. The program also enables the user to analyse a single bridge deck and obtain a transverse distribution profile of the shear forces, bending moments, torsion moments, rotations and deflections at a given section under the action of various traffic loadings specifications.