A simple one-story portal frame is subjected to the 'fling effect present in the ground acceleration record of Santa Monica City Hall Grounds during the 1994 Northridge earthquake as shown in the figure. The properties of the frame are: mass=1kN s2/mm, lateral stiffness=400 kN/mm and damping = 5% critical. Plot the lateral displacement time-history of the floor for two cases: a) The portal frame remains elastic throughout the loading and b) The portal frame behaves elasto-plastically with all columns simultaneously yielding at lateral load of 500 kN. Use the constant average acceleration method with a time step of 0.02 s. Time Acceleration (s) (mm/s2) 9.40 27 1000 9.42 -158 800 9.44 -230 9.46 -285 600 9.48 -391 9.50 -496 400 9.52 -434 9.54 52 200 9.56 598 Time (s) 9.58 738 9.60 577 9 9.5 9.6 9.7 9.8 -200 9.62 319 9.64 191 -400 9.66 -72 9.68 -645 -600 9.70 -866 9.72 -696 -800 9.74 -355 9.76 -127 -1000 9.78 -115 9.80 -19 Acceleration (mm/s2 A simple one-story portal frame is subjected to the 'fling effect present in the ground acceleration record of Santa Monica City Hall Grounds during the 1994 Northridge earthquake as shown in the figure. The properties of the frame are: mass=1kN s2/mm, lateral stiffness=400 kN/mm and damping = 5% critical. Plot the lateral displacement time-history of the floor for two cases: a) The portal frame remains elastic throughout the loading and b) The portal frame behaves elasto-plastically with all columns simultaneously yielding at lateral load of 500 kN. Use the constant average acceleration method with a time step of 0.02 s. Time Acceleration (s) (mm/s2) 9.40 27 1000 9.42 -158 800 9.44 -230 9.46 -285 600 9.48 -391 9.50 -496 400 9.52 -434 9.54 52 200 9.56 598 Time (s) 9.58 738 9.60 577 9 9.5 9.6 9.7 9.8 -200 9.62 319 9.64 191 -400 9.66 -72 9.68 -645 -600 9.70 -866 9.72 -696 -800 9.74 -355 9.76 -127 -1000 9.78 -115 9.80 -19 Acceleration (mm/s2