Cyclic behavior of non-ductile reinforced concrete moment joints strengthened with polymeric composites overlays

This paper presents the results of a pilot research investigation on the use of Fiber Reinforced Polymer (FRP) composites in repair and retrofit of reinforced concrete moment frame joints. In this program, a total of twelve full-scale reinforced concrete moment frame connection tests were performed. Results obtained from the latest six specimens repaired and rehabilitated using carbon/epoxy composite laminates are presented. Two connection specimens were used as control specimens and were tested to failure under inelastic reversal cyclic loading regime. The two "repairable" damaged specimens were re-tested under a similar loading regime after being repaired with both epoxy injection and carbon/epoxy laminates. To investigate the performance of the composite systems as retrofit systems, two other full-scale tests were conducted on undamaged specimens strengthened with specially designed carbon/epoxy laminates. P/delta and M/Theta hysteresis curves for each connection and the associated mode of failure are presented. Discussion on the advantages of using carbon epoxy laminates and recommendations for future research are presented. The results from a simple analytical model describing the behavior of connections retrofitted with composites are presented. The results of the analytical model are in good agreement with the experimental results.