Evaluation of Dynamic Impact Factor for Florida Highway Bridge by Experiment and Finite-Element Method (05-0871)
Jerry Wekezer, Florida A&M University - Florida State University
Hongyi Li, Florida A&M University - Florida State University
Leslaw Kwasniewski, Warsaw University of Technology, Poland
Jerzy Malachowski, Florida A&M University - Florida State University
Jean Ducher, Florida Department of Transportation

The paper deals with the analytical and experimental study on determination of the actual dynamic impact factor of Florida highway bridges. Knowledge of the impact factor is very helpful to determine load carrying capacity and evaluate existing bridges. It can help to make management decisions like establishing of permissible weight limits. Static and dynamic tests were performed on a selected two-lane highway bridge built on US 90 in 1999. The three-span bridge is a concrete, cast-in-place structure with simply supported girders and continuous deck. One or two fully loaded trucks traveled over the bridge, which was instrumented with strain gauges, accelerometers and displacement transducers. The data collected from the tests were used for comprehensive assessment of the bridge under dynamic loading. Detailed 3-D finite element models were developed for the test truck and bridge and simulations were conducted using LS-DYNA explicit code on the super computer at the Florida State University. The simulation results were found to match well with the experimental data. The impact factor is obtained and it shows that the impact factor recommended by AASHTO is higher than actual value in most cases.