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where,
me is the equivalent lumped mass
K is the frame stiffness, k/in
KL is a load factor.
The product KKL is the equivalent stiffness due to a unit load applied at
me. The load factor, KL, is given by:
EQUATION:
KL = 0.55 (1  0.25[beta])
(113)
where,
[beta] = base fixity factor; 0 for pinned base; 1.0 for fixed base
(a) The equivalent mass, me, to be used in calculating the
period of a sidesway mode consists of the total roof mass plus 1/3 of the
column and wall masses. Since all of these masses are considered to be
concentrated at the roof level, the mass factor, KM = 1.0.
The limiting resistance, Ru, is given by:
EQUATION:
Ru =[alpha]wH
(114)
where,
w = equivalent static load based on the dynamic load factor for a
panel or combined sidesway mechanism.
The equivalent elastic deflection, XE, corresponding to Ru is:
EQUATION:
XE = Ru/KE
(115)
(b) The ductility ratio for the sidesway deflection of the frame
can be computed using the dynamic response chart, Figure 67 of NAVFAC
P937. The maximum deflection, Xm, is then calculated from:
EQUATION:
Xm = [mu]XE
(116)
where,
[mu] = ductility ratio in sidesway.
2.08162


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