Chapter 11 Design of Beams (Sections 1 and 2)

Recall, with beams we have two stresses to deal with, normal stress, , and shear stress, 

How are the design of these beams different???

Beam Recap: Beams are structural members designed to support loads applied perpendicular to longitudinal axis. Must be sized adequatly to reduce both shear stress and bending stress as well as shear flow if beam fabricated with fasteners! –Shear stress – issue with wooden beams, short beams, beams with narrow sections (small t) or glued beams.

Beam Recap Cont’d” –Bending stress – generally the stress designed to. Especially for long beams, steel beams, etc. –Recall: Let S = section modulus = I/c, then:

Beam Design Summary: Find shear and moment diagram – get Vmax and Mmax. Determine material and type of beam. Calculate required section modulus using: Calculate max shear stress to make sure ok: Optional: If fabricated with fasteners determine fastener spacing S =Fsd/q If glued, calculate shear stress at glue joint to make sure ok! Design Cross-Section!!!!

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