A six storey reinforced concrete frame was analysed inelastically using a 2 dimensional dynamic analysis computer program. The program utilises the step-by-step integration method for the solution of the equations of motion. Two natural and three artificial acceleration
records were used. Harmonic motions of differing frequencies and each followed by a relatively long acceleration pulse were studied using artificial records created for the purpose. A very approximate allowance for the effects of concurrent earthquake excitation in the orthogonal direction was made by reducing the available column capacities. Parameters studied were ductility requirements, deformations, and column forces.