Simplified method of analysis accounting for shear-lag effects in composite bridge decks

This paper proposes a simplified method of analysis for the design of twin-girder and single-box steel-concrete composite bridge decks. Its main advantages rely on (i) the use of the real width of the slab for the whole bridge length when performing the global analysis, i.e. without modifying the deck geometry based on the effective width method, and (ii) its ability to evaluate the normal longitudinal stress distribution on the slab by means of a cross-sectional analysis considering the internal actions obtained from the global analysis. In the latter cross-sectional analysis the properties of the concrete component are based on an effective width calculated using new analytical expressions presented in this paper. The proposed approach is capable of handling different loading conditions, such as constant uniformly distributed loads, envelopes of transverse actions due to traffic loads, support settlements and concrete shrinkage. These analytical expressions have been obtained based on the results of an extensive parametric study carried out by means of the finite element formulation described in the first part of the paper. The accuracy of the proposed approach is validated for a typical four-span bridge with constant cross-section throughout its length against the results obtained based on the finite element method. Finally, a realistic case study of a bridge with varying cross-section is considered to show the robustness of the proposed methodology.

Research Highlights
► Simplified method of analysis accounting for shear-lag effects.
► Main parameters affecting the occurrence of shear-lag effects.
► Analytical solutions for the effective width.