Parameter [a.sub.1] is equal to 465 mm, 300 mm, and 210 mm for specimens SAC7, SAC5, and SAC3, respectively The horizontal length of each void is 1.25 times the beam overall depth ([L.sub.v1] = [L.sub.v2] = 1.25D).
All specimens SAC3, SAC5, and SAC7 were used for the parametric study which was carried out on the geometry of the voids by defining three design parameters, [alpha], [beta], and [gamma].
Figures 9, 10, and 11 show the effect of design parameters [alpha], [beta], and [gamma] on the ductility of the modified specimens SAC7, SAC5, and SAC3. Connection ductility was evaluated by using parameter 0CWC, which is the total rotation of the connection at the column web center.
Figures 12, 13, and 14 show the effect of design parameters [alpha], [beta], and [gamma] on the strength of the modified specimens SAC7, SAC5, and SAC3. Connection strength was evaluated by using the M/[M.sub.P] ratio which is the ratio of the applied moment measured at the column face level at the failure time to the full beam plastic moment capacity at the column face level.
Despite of the increase in the ductility of the specimens SAC5 and SAC3 (the ductility of nonmodified specimens SAC5 and SAC3 are 0.02 and 0.03 radian, resp.
For instance, in Figures 15 and 16 the moment-rotation curves of the modified specimen SAC7 and SAC3 for [alpha], [beta], and [gamma] equal to 2, 0.75, and 0.1, respectively are compared for both monotonic and cyclic loading.
By decreasing the beam overall depth, for shallower beam specimen SAC3, the amount of pinching significantly reduced.