ABSTRACT
This chapter explores sawn, glued laminated, and engineered lumber beams and joists. It discusses the parameters to consider, some preliminary sizing tools, and how to do the in-depth calculations. The middle deformation is the same as for a simply supported beam, but, over the middle supports, where the beam is continuous, the tension and compression change places–tension on top, compression on bottom. In timber design, we work in stress units, unlike for steel, concrete, and masonry, where we work in strength units. We first consult the reference design values–which give us our starting allowable stress or stiffness– and then the adjustment factors that modify these values for various influences. In the single-span, simply supported beam case, the bending stress is zero at the ends and maximum at the middle. A cantilever is the opposite, with maximum stress at the supported end.
