WORLD FOR CIVIL

Statics & Strength of Materials

Topic 5.6a - Problem Assignment 1 - Beam Inertia, Bending Moment, Stress

1. Asquare box beam is made of four full size 2"x10"s. (See Image) Calculate the moment of inertia and section modulus of the beam. (1386 in⁴, 231 in³)

2. A book shelf is to be made of a clear pine board 1"x10". Determine the moment of inertia and section modulus of the 1"x10". (.833 in⁴, 1.66 in³)

3. The maximum bending moment in a rectangular 2"x 8", 12 foot long beam is 1150 foot pounds. Determine the maximum bending stress in the beam. (647 psi)

4. Determine the maximum bending moment that can be applied to a rectangular 6"x10" beam if the allowable stress in the member is 1200 psi. (120,000 in-lb = 10,000 ft-lb)

5. A wooden cantilever beam has a maximum bending moment of 3600 foot pounds. A rectangular wood beam, 12" high, is to support the load. If the allowable axial stress in 2000 psi., what is the minimum width of the beam needed to support the load? (.9")

6. Determine the moment of inertia and section modulus of a beam made of a solid rod 3 inches in diameter. Also determine the moment of inertia and section modulus of a beam made of a 3 inch diameter pipe with 1/4 inch walls. (3.98 in⁴, 2.65 in³, 2.06 in⁴, 1.38in³)