1. Find the Weight of One Wall of a Building When

CIEG 407 Building Design

Homework 3

1.  Find the weight of one wall of a building when:

a.  Wall is 10 ft tall and 40 ft long

b.  Wall framing is 2x6 wood studs @ 16” o.c.

c.  Interior covering is 5/8” drywall

d.  Exterior covering is 3/8” siding

ANSWER: 12 psf x 10ft x 40ft = 4800 #

2.  Find the weight of one wall of a building when:

a.  Wall is 10 ft tall and 40 ft long

b.  Wall material is 8” thick medium density hollow concrete masonry units (CMU) with grout at 32” o.c.

ANSWER: 47 psf x 10ft x 40ft = 18,800 #

3.  Find the weight of a wood floor system that is 24 ft x 52 ft.

a.  Wood floor system consists of 2x10 joists @ 12” o.c.

b.  Plywood subfloor is ¾” thick

c.  9” of fiberglass insulation in between the joists

d.  Finish floor is hardwood

ANSWER: [7 psf (joists) + 3 psf (3/4” plywood subfloor) + (1.1x9) (insulation) + 4 (hardwood)] x 24ft x 52ft = 23.9 psf x 1248sf = 29,827.2 #

4.  Will a concrete masonry exterior wall home (24 ft x 52 ft) that weighs 135 psf slide on soil that has an angle of internal friction of 250 when the wind pressure on the long side is 40 psf? The walls are 8 ft high and the roof pitch is 12:12. The roof ridge is parallel to the long dimension. Assume the wind pressure is constant for the full height and length of the building and assume there is no resistance provided by foundation or passive soil pressure. (Yes or No – justify your answer)

ANSWER: building weight = 24x52x135 = 168,480 #

Tan 250 = .466

Sliding resistance = 0.6x168,480x.466 = 47,138.1 #

Lateral force = 40psf x 20ft x 52ft = 41,600 #

Building will not slide: resistance > lateral force

5.  Will the house overturn about the narrow dimension if the house is the same size as in Problem 4 except it is a wood frame structure

a.  The structure weighs 60 psf.

b.  The lateral pressure on the long dimension of the house is 50 psf

c.  Answer Yes or No – justify your answer

ANSWER: Overturning resistance = weight x moment arm = 0.6x60psf x 24ft x52ft x12ft (moment arm) = 539,136 ft-lbs

Lateral force overturning = 50psf x 20ft x 52ft x 10ft (moment arm) = 520,000 ft-lbs

Building will not turn over: resistance > lateral force

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