A framework for statistical distribution factor threshold determination of steel–concrete composite bridges under farm traffic

• The statistical framework to determine distribution factors was proposed.
• The framework consisted of field tests, simulations, and statistical analyses.
• Procedures to compute distribution factors for a sample rural bridge were detailed.
• The resulting distribution factors were compared to the AASHTO values.

This paper presents a novel statistical framework to determine distribution factors (DFs) for steel–concrete composite girder bridges subjected to agricultural vehicles. The framework consists of multiple parts including live load field testing, finite element simulations, and statistical analyses. For field testing, strain sensors are installed at critical locations to monitor strain data resulting from passes of test agricultural vehicles. Measured strains are utilized to determine experimental DFs and also used to calibrate finite element models. As part of the model simulation, a number of vehicles of interest are selected and applied to the models to compute analytical DFs. Statistical thresholds for each group of interior and exterior girders are calculated by performing a statistical analysis of the computed data. To demonstrate this procedure, a sample application of interest is discussed. Findings indicate that the proposed framework is capable of reasonably estimate lateral live-load DFs for interior and exterior girders of the particular rural bridge under the effect of varying agricultural loads. The proposed framework is anticipated to provide a more sophisticated live load distribution characteristics’ estimate on such bridges loaded.