The results of theoretical prediction of the inelastic seismic response to selected severe earthquake motions of
f our prototype ductile frames are reported. The structures
 were proportioned in accordance with capacity design principles for loads corresponding with the loading requirements for
seismic Zone C of New Zealand. The effects of P-delta secondary moments on seismic response are briefly reported. A three
 storey frame, in which factored gravity loads rather than specified lateral earthquake loads governed the proportioning
 of members, has been examined in detail. It was found that 
in all frames the intended hierarchy of the energy dissipating mechanisms could be maintained during the full El Centro excitation. The analysis predicted very satisfactory performance for all frames, with a few exceptions, with frames where members were provided with a minimum amount of reinforcement.