iii. For beams in partially restrained

moment frames, *EI*b in Equation 6-7 is modified to:

1

EIb (adjusted) =

(6-9)

6h

1

+

l2 K Θ EIb

b

Stiffness of link beam, kip/in

where:

(kN/mm) =

in. (mm) *K*2 = Rotational spring stiffness, estimated

GAw

as MCE/0.005, kip-in per rad (MCE/0.044, kN-m per

(kN/mm) =

rad.).

connection, kip-in. (kN-m)

(kN/mm) = 12EIb/e3.

iv. For link beams in eccentric braced

frames:

2. Concrete moment frames. Acceptance

criteria for reinforced concrete beams, columns, and

2 y = *Q*CE/*eK*e

(6-10)

beam/column joints in moment frames are tabulated

in Chapter 7. The numerical values are given as the

where:

plastic rotation angles in radians as defined in Figure

6-2. As described in Paragraph 6-3b(2)(b)1 above,

2 y = Yield deformation of the link, rad.

the total chord rotation may be assumed to be equal

to the interstory drift ratio, ) /h, and the yield chord

Expected shear strength of link

rotation, 2 y, for beams and columns is assumed to

beam, kips (kN) = 0.6 *F*ye Aw

be:

2y=

(6-11)

where:

db = Depth of link beam, in (mm).

tf = Thickness of link beam flanges, in.

(mm).

6 - 11

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