DETERMINATION OF THE RIB-TO-CROSSBEAM STRESSES IN ORTHOTROPIC STEEL DECKS

Abstract

For long span bridges, the orthotropic steel deck (OSD) is the most popular option for the bridge deck. Normal OSDs consist out of the steel bridge deck, the longitudinal stiffeners (ribs), and the transversal beams. All of the elements are welded together. The welds create geometrical discontinuities that will result in concentrations, which lead to fatigue damage under repetitive loading. In this research, a simplified calculation method for determining the dimensions of OSDs is developed. This method shares the same notion as the Pelikan-Esslinger method, which is using an idealized orthotropic plate. Solving the idealized orthotropic plate, the internal forces of the actual OSD may be acquired. To calculate the distortional stresses, the shear deformation is treated as an independent variable and added to the simplified calculation method. The system of partial differential equations is derived through the equilibrium relationships of the substituting plate. Three rigidity coefficients are required in this method, namely the flexural rigidity coefficient, the torsional rigidity coefficient, and the shear rigidity coefficient. The former two are the same as in the Pelikan-Esslinger method. By performing a frame analysis, the formulas of the shear rigidity coefficient are achieved. Then, a simple local model is proposed for calculating the nominal distortional stress under the weld of the wall of the rib. To summarize, this research shows the possibility of optimizing the prevailing design the rib-to-crossbeam connection. The proposed fatigue life assessment method and simplified calculation method could be adopted in the future.