SEISMIC BEHAVIOR OF BRIDGE COLUMN NON-CONTACT LAP SPLICES

This study formed part of an on-going research program, sponsored by the Illinois Department of Transportation, to examine seismic retrofit methods appropriate to the type of bridge columns and support foundations existing in Illinois. Full scale field tests confirmed the seismic vulnerability of lap splice details commonly used in bridge columns constructed during the 1960s and also demonstrated that the as-built lap splices were typically non-contact, rather than contact, as shown on the design drawings. Laboratory tests were made, modeling the lap splice details found in the field, and involving systematic variations in concrete cover, column bar circumferential spacing and dowel and column bar radial separation. From the combination of the field and laboratory results an analytical model is developed that provides reasonable predictions of the strength, stiffness and ductility of circular bridge columns with inadequate length non-contact lap splices at their base.