Behavior of open steel grid decks for bridges

Abstract

The life cycle of grid decks has come full circle from their introduction in the 1920s and 1930s, through their maturity in 1950s and 1960s, to their reintroduction in the 1980s. Many of these decks have been performing satisfactorily for 50 or more years of service. Open grid decks offer a lightweight deck alternative to reinforced concrete decks. Despite the good performance history of grid decks, some bridge owners are hesitant to utilize them, even in situations where weight savings is at a high premium. With a better understanding of grid deck behavior, the manufacturing process can be optimized, and design methods improved. Hence, poor details that may lead to fatigue problems can be avoided and design efficiency can be achieved. This paper presents results of research conducted with the goal of providing a better understanding of open steel grid deck behavior through experimental testing and numerical and analytical analyses. Four full-scale open grid decks were tested to experimentally quantify their structural behavior. Three-dimensional finite element models were developed for the grid decks and calibrated using the experimental results. Classic orthotropic thin plate theory and the theory for beams on elastic foundation were applied to the open decks and compared with the finite element (FE) results. Finally, parametric studies were conducted and used to quantify the effect of variations in the significant design parameters. The results of the parametric studies can be applied to optimize future grid deck designs.