8/6/2019 Structure Design Example

1/4

1

Roof Loading

Live Load = 20 psf Dead Load:

Standard Roof: 10 psf Drain Material: 3 psf Saturated Media: 91 (lb/ft) * (4 (in) / 12) = 30.4 psf Plants: 2 psf Total: 45.4 psf

Tr ibu ta ry Area

12 ft

20 ft

Tr ibu ta ry Area

12 ft

20 ft Sizing Raf te rs

6-87-79-624

7-58-610-719.2

8-19-411-716

9-510-913-512

2 x 6

No. 2No. 1S.S.SpacingSize

LL = 20 psf DL = 50 psf

Sizing Raf te rs

8-79-711-1024

9-710-913-319.2

10-611-914-616

12-113-716-912

2 x 8

No. 2No. 1S.S.SpacingSize

LL = 20 psf DL = 50 psf

Girder Sizing

8/6/2019 Structure Design Example

2/4

2

Tr ibu ta ry Area

12 ft

20 ft

6 ft

Girder Sizing

Tributary Area = 6 ft/ft

Load = 6 ft/ft * (20 psf + 45.4 psf ) = 393 lb/ft

Span = 10 ft

Girder Sizing Girder Sizing

393 / 210 = 1.87 = 2210 lb/ft2x12

393 / 150 = 2.62 = 3150 lb/ft2x10

393 / 95 = 4.14 = 595 lb/ft2x8

393 lb/ft / 50 lb/ft = 7.86 = 850 lb/ft2x6

# NeededAllowable

LoadSize

Wh a t i f w e w a n t asma l l e r beam?

Tr ibu ta ry Area

12 ft

20 ft

6.7 ft

8/6/2019 Structure Design Example

3/4

3

Girder Sizing

Tributary Area = 6 ft/ft

Load = 6 ft/ft * (20 psf + 45.4 psf ) = 393 lb/ft

Span = 6.7 ft

Girder Sizing

Girder Sizing

393 / 475 = 0.83 = 1475 lb/ft2x12

393 / 320 = 1.23 = 2320 lb/ft2x10

393 / 200 = 1.97 = 2200 lb/ft2x8

393 lb/ft / 120 lb/ft = 3.28 = 4120 lb/ft2x6

# NeededAllowable

LoadSize

Column Sizing

Tr ibu t a ry Area

12 ft

20 ft

10 ft

6 ft

Column Load ing

Tributary Area = 6 ft x 10 ft = 60 ft

Load = 60 ft x (20 psf + 45.4 psf ) = 3924 lbs

Effective Length = 10 ft

8/6/2019 Structure Design Example

4/4

4

Column Load ing

1237097207390472010 ft.

4x104x84x64x4EffectiveLength

Tr ibu ta ry Area

12 ft

20 ft

6.7 ft

6 ft

Column Load ing

Tributary Area = 6 ft x 6.7 ft = 40.2 ft

Load = 40.2 ft x (20 psf + 45.4 psf ) = 2629 lbs

Effective Length = 10 ft

Column Load ing

1237097207390472010 ft.

4x104x84x64x4EffectiveLength

Foot er Sizing

Column Load = 3924 lb

Footer Area = 3924 lb / 2000 lb/ft = 1.96 ft

Footer Dimensions = 1.4 ft x 1.4 ft

Footer Depth = 1.4 ft / 2 = 0.7 ft