Long‐Span Bridge Computer Modeling

The Queensboro Bridge in New York City is presently undergoing major rehabilitation to its road surfaces and wind bracing system. A three dimensional computer model of this bridge was developed since significant cost savings were feasible if accurate analyses of the structure could be provided during the 15‐yr rehabilitation period. The size of the model was reduced considerably by simplifying ornate portal frames and neglecting the contribution of the floor systems (upper and lower) to the torsional rigidity of the entire structure. The accuracy of the model was verified by comparison to previously computed geometry and member stresses. The first use of the three dimensional model resulted in providing the contractor maximum flexibility in conducting his work and thus should reduce his costs.