The Canadian Standard, CSA A23.3-94, limits the concrete compressive strength used in seismic design to 55 MPa. The applicability of the current design specifications, developed for normal-strength concrete, were investigated when applied to ductile beam-column joints made with higher strength concrete. The reduced amount of confinement reinforcement permitted by the New Zealand Standard is also investigated. All specimens in the study were instrumented to allow for detailed strain, load and deflection measurements to be monitored during testing process. The hysteretic behaviour of each specimen was analysed in order to investigate energy dissipating characteristics as well as attainable ductility levels. Strains in the slab bars were used to determine the amount of effective slab reinforcement which contributes to the negative flexural capacity of the main beam. Deflection and strain measurements were used to determine the full torsional response of the spandrel beams. Non-linear dynamic analyses were also performed to compare the predicted seismic performance of normal-strength concrete and high-strength concrete prototype structures.