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The results of a comprehensive experimental program, aimed at providing a fundamental understanding of the behavior of shear-critical exterior reinforced concrete ͑RC͒ joints strengthened with fiber reinforced polymers ͑FRP͒ under simulated seismic load, are presented in this study. The role of various parameters on the effectiveness of FRP is examined through 2/3-scale testing of 18 exterior RC joints. Conclusions are drawn on the basis of certain load versus imposed displacement response characteristics, comprising the strength ͑maximum lateral load͒, the stiffness, and the cumulative energy dissipation capacity. The results demonstrate the important role of mechanical anchorages in limiting premature debonding, and they provide important information on the role of various parameters, including: area fraction of FRP; distribution of FRP between the beam and the column; column axial load; internal joint ͑steel͒ reinforcement; initial damage; carbon versus glass fibers; sheets versus strips; and effect of transverse beams.

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Destructive Testing, like core drilling, remains today the only reliable method to calculate with accuracy concrete's strength parameters. However, the damage of the constructions is always a limitation. On the contrary, Non-Destructive Tests (NDT) are fast and cost-effective which make them attractive nowadays. Nevertheless, the results of Ultrasonic Pulse Velocity (UPV) test are highly dispersed. Therefore, it is necessary to combine them along with destructive tests. The purpose of this study is to investigate the feasibility to adopt the Sonic Resonance (SR) test to determine the strength parameters of the concrete. UPV and SR were used in conjunction with the Uniaxial Compression Test. Experimental and numerical analysis were conducted. More than 200 concrete cores from existing constructions were tested and more than 70 Finite Element Method (FEM) models were simulated. The results were correlated, and two empirical equations derived. It was observed that the dispersion of the of SR alone is smaller than the UPV, but also the UPV dispersion can be narrowed as long as the Poisson's ratio is known.