Self

Long

Short

Total

Total

Supporting

Direction

Direction

Total

Floor

Floor

Total

Total

Dead

for gravity

Brick

Brick

Room

Corridor

Floor

Panel Dead

Floor

Floor Floor

Dead

Story

Exterior

Exterior

Interior

Interior

Load

Brick

Veneer

Veneer

Live

Room

Live

Corridor

Live

Level

Load Length Width Area Load, D Height

Walls

Walls, EW

Walls Walls, IW DT=D+EW+IW

Veneer

BL

BS

Load

Area

Load

Area

Load, L

(ft2)

(ft2)

(ft2)

(psf)

(ft)

(ft)

(kips)

(ft)

(psf)

(kips)

(psf)

(kips)

(kips)

(psf)

(kips)

(kips)

(psf)

(psf)

(kips)

Roof

3rd

20

164.42 54.67 8988 179.762

4.2

10

18.5

10

30.09

228.4

40

55.6

18.5

0

7892

0

1096

0

2nd

45

164.42 54.67 8988 404.465

9.0

10

39.3

10

63.74

507.5

40

117.8

39.2

40

7892

80

1096

403

1st

45

164.42 54.67 8988 404.465

9.3

10

40.7

10

66.11

511.3

40

122.2

40.6

40

7892

80

1096

403

The ground snow load, pg, for Fort Lewis is 20 psf3. The flat-roof snow load, pf, is calculated as

follows (ASCE 7-95, Eq 7-1)4:

pf = 0.7CeCtIpg = 0.7(0.9)(1.0)(1.0)(20psf ) = 12.6psf

(Eq D-2)

Where:

Ce = the exposure factor (ASCE 7-95, Table 7-2), which for an exposure category C, fully

exposed roof is 0.9.

Ct = the thermal factor (ASCE 7-95, Table 7-3), which is taken as 1.0.

I = the importance factor (ASCE 7-95, Table 7-4), which for Category II of the barracks

building is 1.0.

However, the flat-roof snow load shall not be less than the ground snow load multiplied by the

importance factor (pgI), so that the pf = 20 psf. The sloped-roof snow load, ps is calculated as follows

(ASCE 7-95, Eq 7-2):

ps = Cspf = (0.75)(20psf ) = 15psf

(Eq D-3)

Where:

Cs = the roof slope factor (ASCE 7-95, Figure 7.2), which is 0.75 for the barracks building with

a 5/12 roof slope.

The snow load will not be used in this example because the flat roof snow load does not exceed 30

psf, and therefore is not included in load combinations that include seismic forces.

D6. EARTHQUAKE FORCE DEFINITION. Seismic forces are now defined based on the equivalent

lateral force procedure (see Appendix C, Paragraphs C6 through C9). The seismic base shear, V in

the direction of the shear walls is given by (Equation C-19):

V = Cs W

(Eq D-4)

The seismic response coefficient, Cs (Equation C-20) is calculated with the variables given in Table

D-1, which becomes:

=

= 0.204*g*

(Eq D-5)

4

1.0

The value of for Cs need not exceed the following (Equation C-21), where T = Ta (see Equation D-8):

3

ASCE 7-95, Chapter 7 and Chapter 7 Commentary.

4

NEHRP, Section 5.3.2, states that in areas where the design flat roof snow load does not exceed 30 psf, the effective snow

load is permitted to be taken as zero. The Commentary to the 1997 NEHRP (FEMA 303) Section 5.32, states that " now loads

s

up to 30 psf are not considered,"in the weight, W, used to calculate the lateral earthquake loads.

D-3

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