Analysis and Monitoring of Southington I-84 Bridges during Accelerated Bridge Construction

The Southington I-84 Eastbound and Westbound Bridges over Marion Avenue in Southington, Connecticut (Bridge Nos. 01235 and 01236) were replaced in 36 hours under CTDOT’s accelerated bridge construction program. Both superstructures were built offsite and moved into place using Self-Propelled Modular Transporters (SPMTs). Each bridge was instrumented and multiple finite element models of westbound bridge were developed in order to quantify the maximum allowable structural twist the bridge could tolerate during the SPMT move while ensuring resulting stresses would be below the allowable stresses. The change of support locations was analyzed in order to capture the states of stress resulting from the differing support conditions at different construction stages. This included simply supported end conditions on the temporary towers to cantilevered end conditions on the SPMT’s. Additionally, four different deflection cases were analyzed at each SPMT support corner in order to represent a worst case scenario of a local loss of support during the bridge move.