CIEG 407 Building Design

CIEG 407 Building Design

Homework # 2 Answer Key

1.  Find the most restrictive vertical load combination using ASD when:

a.  Dead load is 60 psf

b.  Floor live load is 40 psf

c.  Roof live load is 20 psf

d.  Snow load is 30 psf

e.  Wind load is 25 psf

f.  Seismic load is 10 psf

g.  Tributary area is 200 sf

D = 12 k

LL = 8 k

Lr = 4 k

S = 6 k

W = -5 k

E = 2 k

So: 1. D = 12 k

2.  D+L = 20 k

3.  D+S = 18 k

4.  D+.75L+.75S = 22.5 k MOST RESTRICTIVE

5.  D+W = 12-5 = 7 k

6.  D+.75W+.75L+.75S = 18.75 k

7.  .6D+W = 2.2 k

8.  N/A

2.  Find the most restrictive vertical load combination using strength design when:

a.  All of the loads in # 1 above are the same

b.  Tributary area is 200 sf

Using loads from above:

1.  1.4D = 16.8 k

2.  1.2D+1.6L+0.5S = 14.4+12.8+3 = 30.2 k

3.  14.4+1.6S+8 = 32 k MOST RESTRICTIVE

4.  14.4-8+8+3 = 17.4 k

5.  14.4+8+.2S = 23.6 k

6.  .9D+1.6W = 10.8-8 = 2.8 k

7.  10.8+0 = 10.8 k

3.  Find the most restrictive horizontal load combination using strength design when:

a.  Dead load is 60 psf

b.  Floor live load is 40 psf

c.  Roof live load is 20 psf

d.  Snow load is 30 psf

e.  Wind load is 25 psf

f.  Seismic load is 10 psf

g.  Flood load is in a V Zone and is 50 psf

h.  Tributary area is 80 sf

Calculating loads:

D = 60x80 = 4.8 k

LL = 3.2 k

Lr = 1.6 k

S = 2.4 k

W = 2 k

E = .8 k

Fa = 50x80 = 4 k

1.  1.4D = 6.72 k

2.  1.2D+1.6L+0.5S = 12.08 k

3.  1.2D+1.6S+L = 12.8 k

4.  1.2D+1.6W+2.0Fa+L+0.5S = 21.36 k MOST RESTRICTIVE

5.  1.2D+1.0E+L+0.2S = 10.24 k

6.  0.9D+1.6W+2.0Fa = 15.52 k

7.  0.9D+1.0E = 5.12 k

4.  Determine the probability of an event occurring during the 60 year life of a building when the mean recurrence interval for the event is:

a.  50 years

b.  250 years

Pn = 1 – (1-Pa)n

a.  n = 60, Pa = .02, Pn = .7024

b.  n = 60, Pa = .004, Pn = .2138

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