Structural Evaluation of the John A. Roebling Suspension Bridge

The primary objective of the structural evaluation of the John A. Roebling Bridge is to determine the maximum allowable gross vehicle weight (GVW) that can be carried by the bridge deck structural elements such as the open steel grid deck, channels, standard sections, or built-up sections. To achieve this objective, an "Element Level Analysis" is carried out. The maximum allowable GVWs for different truck and bus types are presented for different levels of structural elements sectional loss. The loss or reduction in element sectional properties is due to rust, cracks, etc. The "Element Level Analysis" is the most critical and yielded the maximum allowable gross vehicle weights. The critical member in the bridge deck is the built-up 36 inch deep section. Its allowable bending strength controls the maximum GVW that can be permitted on the bridge. Results are presented for different levels of sectional losses (10% to 40%, in 10% increments). In the event that replacement of the open grid deck will take place in the future, results are presented for different deck weights (10 psf to 50 psf in 10 psf increments). The current open grid deck weight is 20 psf.