| Accelerated Bridge Construction (ABC) technologies are being adopted by federal and state departments of transportation because they reduce construction time and expense and mitigate other problems such as traffic stoppages. One particular ABC technology is the use of precast concrete members joined with mechanical connections. However, in some states where there is moderate to high seismic activity the use of mechanical connections in precast members has not been adopted either because it is not known how these mechanical connections will behave in a seismic event or the risk of failure is considered too great. The Idaho Transportation Department (ITD) has requested that a literature review and an analytical study be conducted on some typical Idaho bridges with mechanical connections to observe their behavior in an earthquake. Three Idaho bridges were chosen for this study. Three different analytical models were made for each bridge: a model with cracked linear-elastic columns, a model with nonlinear cast-in-place (CIP) columns, and a model with nonlinear columns with grouted couplers. The models, which were written in OpenSees, were subjected to loads that might be expected in an earthquake in Idaho in the transverse and longitudinal directions. In general, the models with the grouted couplers behaved much the same as the nonlinear CIP models in both directions. The cracked linear-elastic models, however, tended to have larger column base reactions and smaller displacements in the transverse direction. The displacement/drift demand and capacity of the bridge columns were calculated using the method outlined in the American Association of State Highway and Transportation Officials (AASHTO) Guide Specifications for LRFD Seismic Bridge Design and compared with the displacement/drift results from the analytical models of all of the bridges. These calculated values were larger and therefore more conservative than the results from the analytical models. A single column from the Parma Bridge and the DuboisBridge were also analyzed under large drifts to observe the behavior of the coupler and the reinforcing steel. Both the Parma and the Dubois columns were able to obtain a nonlinear drift value greater than 4 percent before the coupler failed. Based on findings in this study, guidelines were presented for the use of precast columns with grouted couplers for inclusion in ITD’s Idaho Bridge Design Manual. |