ARC322 Quiz 13 2008 KEY

ARC322 Quiz 13 2008 KEY - 2 )/8 = 1515.94 ft-lb S = M/ f =...

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ARC322 Quiz 13 2008 Name ______________ KEY _______________ 9 Points 1 When designing a wood beam, which stress is the most limiting? Horizontal Shear Stress 2 What is the actual cross sectional area of a 4x4? 3.5 in x 3.5 in = 12.25 in 2 3 When designing a wood beam, what is the first stress considered? Bending Stress 4 Which is a higher grade of structural lumber? No.1 and Better or Select Structural? Select Structural 5 A simple wood joist needs to span 10’-6”. Assuming DFLSS ASD is 1725 lb/in 2 , and the DL + LL is 110 lb/ft, what is the required section modulus if the loads are normal to the strong axis? No sketch required. 3 points M = w L 2 /8 = (110 lb/ft x (10.5 ft)
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Unformatted text preview: 2 )/8 = 1515.94 ft-lb S = M/ f = (1515.94 ft-lb x 12 in/ft)/1725 lb/in 2 = 10.55 in 3 = the required section modulus 6 Using the table below, select the most economical wood member for the required section modulus in question 5. The final test must be shown. 2 points 1x10 S = 10.70 in 3 > 10.55 in 3 BUT a 1x is NOT a structural member NOT OK 2x8 S = 13.14 in 3 > 10.55 in 3 OK Area = 10.88 in 2 MOST Economical 3x6 S = 12.60 in 3 > 10.55 in 3 OK Area = 13.75 in 2 NOT most economical 4x5 S = 11.81 in 3 > 10.55 in 3 OK Area = 15.75 in 2 NOT most economical...
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