Daniel Baxter, P.E., S.E. (Michael Baker Jr. Inc.)
David Nemovitz, P.E. (Michael Baker Jr. Inc.)
This paper will discuss the sensitivity of predicted rail-structure interaction effects acting on direct-fixation light rail bridges. Specifically, the effects of variable design-parameters will be evaluated for both the forces due to thermal variation and the predicted gap lengths at rail break events through the use of nonlinear finite-element modeling. The modeling parameters that are considered for the sensitivity analysis include: (1) flexural stiffness of substructure, (2) rail fastener stiffness, and (3) the locations of continuous welded rail terminations. Results will be presented for the design of the proposed bridge carrying the FasTracks I-225 light rail corridor over I-225 in Denver, CO, as well as for an independent analysis of the FasTracks West Corridor LRT over Colfax and 6th in Lakewood, CO. The rail-structure interaction results obtained from nonlinear finite-element modeling will also be compared to results found using equations commonly included in the design criteria for other light rail facilities in the U.S."