Behavior of Steel-to-Concrete Connections for Use in Repair and Rehabilitation of Reinforced Concrete Structures

The need to strengthen non-ductile reinforced concrete frames has been widely recognized as an urgent problem in earthquake engineering. Attaching steel bracing systems and/or steel jackets and plates to existing concrete structures are common approaches used to rehabilitate non-ductile reinforced concrete frames. An effective transfer of forces between the existing concrete members and the attached steel plates or sections is essential for the success of these retrofitting techniques.

Thirty six specimens were tested to study the effect of different variables on the behavior of single-anchor steel-to-concrete connections. The variables studied include: clearance between the hole in the steel element and the anchor bolt, bolt preload, type of filler material acting as an interface agent (non-shrink grout and epoxy), thickness of interface material, surface treatment of the steel element, type of fastening method (standard and spring washers), bolt inclination, and effect of reversed cyclic loads. Test specimen behavior is presented in the form of load-slip relationships, maximum elastic and utimate capacities, and load-slip envelopes. A comparison of the test results with recommended design provisions is presented to provide guidelines for design of steel-to-concrete attachments used in rehabilitation projects.