ENGR 211 Recitation 9

ENGR 211 Recitation 9 - Page 2 of 2 Problem 3 The large box...

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ENGR 211 Recitation 9 Page 1 of 2 Problem 1. If the bridge below is built with Douglas Fir, find the necessary size lumber so that the allowable shear and bending stresses are not exceeded in the beam at point A. σ max = M y max ; where y max = Depth/2 I Allowable Stress (all units in psi) Material* Tension Compression Shear Modulus of Elasticity, E Douglas Fir 1900 1900 120 1.76 x 10 6 Common Lumber Sizes: Nominal Lumber Size Actual Width (inch) Actual Depth (inch) 2x4 1.5 3.5 2x6 1.5 5.5 2x8 1.5 7.25 2x10 1.5 9.25 2x12 1.5 11.25 (Use the long dimension in the vertical orientation.) Figure 1 Side View of Beam Figure 2 Cross-section of beam Problem 2. Find I x’ around the composite centroid.
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ENGR 211 Recitation 9
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Unformatted text preview: Page 2 of 2 Problem 3. The large box on the right is on the verge of sliding downhill. Find the angle α . The friction forces are at maximum. Large box on the right: Weight = 200 lbs. μ s = 0.28 Small Box on the left: Weight = 100 lbs. μ s = 0.15 Problem 4. The cable supports a uniformly distributed load w = 600 N/m. Find T max and the angle of the cable at the connection points if the lowest point of the cable, h = 3 m . Hint: to find the angle of the cable take the derivative of the parabolic equation @ the end point. Problem 5. The mass of the cable per unit length is 2 kg/m. The allowable sag is 3 m. What is the: T max of Cable AB? Length of cable between Tower A and Tower B?...
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This note was uploaded on 03/15/2009 for the course ENGR 211 taught by Professor Tona during the Spring '09 term at Oregon State.

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ENGR 211 Recitation 9 - Page 2 of 2 Problem 3 The large box...

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