In response to a request from the Port of Baltimore to determine whether bridges could accommodate some extremely oversized vehicles travelling on I-695 to and from the Port of Baltimore to the I-95 corridor, Maryland Transportation Authority (MDTA) was interested in improving load rating factors of several permit restricted bridges to reduce the need for individual escorts and bridge closures.
To better approximate the dead and live load demands on superstructure members of the Bear Creek Bridge (B-Z462051) a diagnostic load test was performed. A three-dimensional finite element (FE) model was developed using Bridgemiser to plan instrumentation, predict test responses for confirmation of assumptions and general safety during load testing, and for calibration using test data.
A load test using trucks of known weights and dimensions was then carried out while measuring specific bridge responses. These responses were used to calibrate the Bridgemiser finite element (FE) model to more closely approximate the actual structureâ€™s behavior and the model was then used to compute load ratings and distribution factors using Load and Resistance Factor Design (LRFR) methodology.