Grouted Splice Connections for Accelerated Bridge Construction With Shifted Plastic Hinging

Abstract eng:
Accelerated bridge construction (ABC) has gained popularity in urban areas where construction risk and traffic delays need to be minimized. The use of prefabricated elements is essential in most ABC projects to meet tight scheduling demands. Due to lack of knowledge regarding non-linear performance of connections, prefabricated substructure elements have been utilized more frequently in areas of low seismicity compared with areas with higher seismic hazard. Connections employing grouted coupler splices are becoming one of the more popular options for some U.S. transportation agencies. Previous studies have shown that precast columns with grouted splice connections behave similar to cast-in-place columns when subjected to non-linear cyclic loading. However, these connections have also been shown to disrupt plastic hinge formation, which results in premature failure and reduced displacement ductility. This paper presents the preliminary results from an experimental study on precast concrete columns with grouted splice moment connections. The primary goal of the study is to develop new connection details employing grouted splices that exhibit improved seismic performance compared with previously tested connections details. Four 0.42-scale bridge column models were designed based on Caltrans’ Seismic Design Criteria with different aspect ratios to represent flexural and flexural-shear dominated configurations. Of the four models, two precast columns were designed such that plastic hinging forms above the grouted couplers. In previous studies, columns employing these couplers exhibited concentrated plastic rotation at the column-footing interface, which resulted in premature bar rupture and reduced ductility. Thus, the proposed design method shifts plastic hinging to a region with higher plastic rotation capacity to increase ductility and improve seismic performance. Precast columns are compared with a corresponding set of cast-in-place column models that establish baseline performance. All four columns were subjected to slow cyclic lateral loading in a single cantilever configuration. Hysteretic force-displacement relationships, damage observation and energy dissipation for the precast models are compared with like results from corresponding CIP column models. Furthermore, quantification of the displacement components that contribute to the total lateral displacement is performed to assess the hinging behavior of the precast column compared with CIP column.

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