A preliminary investigation of strains in reinforced concrete beam—column connections due to seismic loading

Two reinforced concrete external beam—column connection specimens were subjected to a series of slow load reversals to simulate seismic effects. Strain distributions were measured using internally strain gauged reinforcement. Specimen C3S, with a 210 mm deep beam, failed after 12 load cycles due to a plastic hinge which developed in the beam at the face of the column; specimen C9S, with a 300 mm deep beam, failed after 10 load cycles due to plastic hinges which developed in the column above and below the beam. Strains of over 17000 microstrain were recorded at the beam hinge in C3S; those in the column hinges of C9S were over 5000 microstrain. Large residual strains were also observed when the load was reversed. Peak bond stresses of∼ 5 N/mm² were recorded early in each test, but the considerable disintegration of the connection zone caused by the load cycling resulted in an almost complete loss of bond in the connection zones by the end of each test.