About the research
Iowa State University (ISU) and the Forest Products Laboratory (FPL) at Madison, Wisconsin have done extensive load testing of timber bridges around the country to study the behavior of timber bridges and improve upon the existing design methodologies for various types of timber bridges. As part of this study effective analysis tools were developed to aid with bridge evaluation of stress-laminated deck, longitudinal deck, and glued laminated girder bridges. Sensitivity evaluations were performed on numerous field bridges that had been previously load tested. The study developed modeling recommendations and computer programs for the analysis and evaluation of both skew and non-skew bridges. The finite element model software developed includes pre- and post-processors for ANSYS. A sensitivity analysis was also performed to determine a reasonable element size and aspect ratio to model the deck elements. These programs were written in ANSYS Parametric Design Language that is available in ANSYS finite element analysis commercial software. The programs require limited input like bridge dimensions, material properties, load, and load positions for analyzing the bridge. The output file contains deflection and stress results at desired cross-sections of the bridge. This output can be imported into the Excel software to represent the results in a graphical manner.