Behavior of steel grid decks for bridges

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 over 50 or more years of service. However, despite the outstanding performance history of these grid decks, some state departments of transportation are hesitant to utilize this type of deck for routine bridges. With a better understanding of the grid deck behavior, design procedures may be improved and products may be optimized. Hence, failure can be avoided and design efficiency can be achieved. The present research program was designed to achieve the goal to better understand the grid decks behavior through experimental testing and numerical and analytical analyses. Four open and three filled full-scale grid decks were tested in the laboratory to experimentally quantify the structural behavior of the open and filled grid decks. Three-dimensional finite element models were developed for both open and filled decks and calibrated to the experimental results. The classic orthotropic thin plate theory was applied to open and filled decks and compared with the FEM results. The theory of beam on elastic foundation was applied to the open grid deck and compared with the plate theory. Parametric studies were conducted on major parameters for open and filled grid decks to quantify the effect of variations in the major parameters and to help in optimizing the design of grid decks.