Temporary Substructure Forces during Bridge Slide: Impact of Sliding Friction and Substructure Alignment

Slide-in Bridge Construction (SIBC) is different from the conventional bridge construction because of the activity required to move the bridge to final position following construction. Moving activity requires bridge to be on a temporary support structure, resting on a sliding system such as bearings suitable for sliding, and a system of force actuation for pushing or pulling the bridge. Two SIBC projects were recently completed in Michigan, USA. SIBC being new to the bridge community, substructure forces that are developed during slides are best estimated. Hence, one of the Michigan projects was selected and slide operation was simulated using dynamic explicit finite element analysis techniques. This article presents use of dynamic explicit finite element analysis for evaluating temporary substructure forces during bridge slide. Further the analysis results are used to explain the impact of unequal friction at sliding surfaces and differential alignment of the temporary supports on substructure forces and bridge superstructure movement. Typically, bridge superstructures are slid in place using forcecontrolled systems. Analysis was performed using force-controlled and displacement-controlled methods. Then, the analysis results are used to explain the benefits of using displacement-controlled methods with force monitoring to slide a bridge rather than employing a force-controlled method