... Engineering Mechanics 12 5, 20 6-2 15 . Richard R.M. and Abbott B.J. (19 75). Versatile Elastic-Plastic Stress-Strain Formula. ASCE Journal of the Engineering Mechanics Division 10 1, 51 1- 5 15 . ... A/Solids 12 ,44 5-4 70. Lui E.M. and Chen W.F. (19 86). Analysis and Behaviour of Flexibly-Jointed Frames. Engineering Structures 8, 10 7 -1 18 . Macki, J.W., Nistri, P. and Zecca, P. (19 93). Mathematical ... This model describes the hysteretic force-deflection skeleton (virgin) curve by a three-parameter polynomial as F F 1 , -1 u(F) = ~-( 1 + A I- ~- ) (1) where u and F represent the deflection...