Bond Studies of High-Strength Concrete Joints Confined with Stirrups, Steel Fibers, or Fiber-Reinforced Polymer Sheets

Abstract

The paper presents a correlation study of the results of three research programs conducted on hooked bars anchored in high-strength concrete (HSC) beam-column joints at the American University of Beirut (AUB). The specimen simulated the rigid connection of a cantilever beam to a column. In two previous programs, the beam-column joint was confined either externally with carbon fiber–reinforced polymer (CFRP) sheets or internally by steel fibers incorporated in the concrete mix. Although stirrups were included in the beam and column elements of the specimens of the two programs, the column stirrups were not extended in the beam-column joint. It was necessary to conduct a third program where confinement of the joint was provided internally by stirrups crossing the critical hooked bars region. Results of the three programs indicated positive effect of the different confining modes on bond strength of the anchored bars and ductility of the load-deflection history. Comparison of the results of the three programs is presented.