| Improved evaluation procedure for highway truss bridges was proposed in three major areas. One area is related to indirect damage identification based on modal data of the damaged bridge and pre-existing baseline bridge information. In the process, the location, magnitude and type of damage in terms of reduction of member cross-section (expressed as loss of area and moment of inertia) and loss of connection capacities were identified. The second area is related to strength evaluation in terms of a new rating factor that accounts for the inherent reserve capacity of the bridge system using shakedown analysis allowing for geometric and material nonlinearities, joint flexibilities, and moving live load. At the shakedown limit a residual displacement of L/1000 was allowed. Finally, a number of procedures were developed to determine the residual fatigue life of a bridge based on the fail-safe concept using elastic fracture mechanics computations and a power law.;The computer simulations were done using three software developed by the author for the planar case, and the commercial software ANSYS in the three-dimensional case. The proposed procedures for the three elements of bridge evaluation were thoroughly checked with the help of three real-life bridge examples. It was concluded that the proposed procedures were successful in the deterministic sense. However, extension of the work into the probabilistic regime is recommended. |
