B-9 *Determine need for overstrength factor, *Ω o .

Per paragraph 8.6.2 of FEMA 302, connections for diagonal bracing members and collectors shall have a

design strength equal to or greater than the nominal tensile strength of the members being connected or

Ω o times the design seismic force.

Therefore, for these *force controlled elements *the following seismic load will be used;

E = Ω oQ E 0.2S DS D

Longitudinal direction;

(EQ. 4-6)

E = 2Q E 0.2(0.57)D

E = 2Q E 0.114D

E = Ω oQ E 0.2S DS D

Transverse direction;

(EQ. 4-7)

E = 3Q E 0.2(0.57) D

E = 3Q E 0.114D

B-10 *Calculate combined load effects.*

Load combinations per ANSI/ASCE 7-95 and TI 809-04 are as follows;

(1)

1.4D

(2)

1.2D+1.6L+0.5Lr

(3)

1.2D+0.5L+1.6Lr

(4)

1.2D+E+0.5L

(5)

0.9D+E

However, per paragraph 4-6 of TI 809-04;

E = *ρ*Q E 0.2S DS D

= 1.0Q E 0.2(0.57)D

= Q E 0.114D

Therefore, equations 4 and 5 become;

(4a)

1.314D+QE+0.5L

(4b)

1.086+QE+0.5L

(5a)

1.014D+QE

(5b)

0.786D+QE

H4-20

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