Development of live load distribution factor equations for girder bridges

The objective of this study is to evaluate and simplified the approach for the computation of the live load distribution factor equation for girder bridges. The live load distribution factor equation is one of the most important bridge design calculation since it provides the distributed moment and forces that are needed for designing new or evaluating existing bridges. The current approach---American Association of State Highway Transportation Officials Load and Resistance Factor Design (AASHTO LRFD) Bridge Design Specification---uses power function that contains parameters that are often unknown when designing new bridges making the design procedure iterative. This iterative design procedure is perceived by many practicing engineers as impractical and has raised questions regarding the level of complexity versus simplicity in bridge design calculations. Therefore, a simpler but accurate live load distribution factor equation is needed.; An experimental program and analytical method for evaluating girder bridges are conducted in this study. The experimental program consisted of live load test of actual girder bridges. A comprehensive sensor network is implemented for field testing and long-term health monitoring of the Doremus Avenue Bridge, located in Newark, New Jersey. The bridge responses and live load distribution factor are evaluated and compared to available analytical methods and live load distribution factor equations.; The parametric study is carryout using detailed finite element analysis to determine the sensitivity of various bridge parameters that affect the live load distribution factor. Based on the experimental program and detailed finite element analysis, a new live load distribution factor equation is proposed. Results show that the proposed equation is simpler than the AASHTO LRFD live load distribution factor while maintaining a level of accuracy.