Strength and ductility of reinforced concrete moment frame connections strengthened with quasi-isotropic laminates

This paper introduces an innovative technique using polymer composites for repair and retrofit of reinforced concrete (RC) moment frame connections. In this pilot study, a total of six half-scale reversal cyclic tests were preformed. The tests were conducted on half-scale specimens simulating interior beam-to-column sub-assemblages of a typical RC structure. Two connection specimens were used as control specimens and were tested to failure. These two "repairabIe" damaged specimens were re-tested under a similar loading regime after being repaired with both epoxy injection as well as carbon-epoxy and E-glass-epoxy quasi-isotropic laminates. To investigate the performance of the composite systems as retrofit schemes, two other half-scale tests were conducted on undamaged specimens strengthened with both E-glass-epoxy and carbon-epoxy quasi-isotropic laminates. Test results indicated that the use of composite overlays has led to an appreciable increase in stiffness, strength, and ductility of these connections. The ductility and strength of the repaired specimens were increased up to 42 and 53% respectively, as compared to the control specimens. Discussion on the advantages and disadvantages of using E-glass-epoxy vs. carbon-epoxy laminates is also presented. (C) 2000 Elsevier Science Ltd. All rights reserved.