The fundamental structural element
in a building is the beam, a horizontal
member that supports something. It's
used everywhere in wood-framed
structures — joists, headers, girders.
In the next two columns, I'd like to
show you how we engineers size these
beams (headers and girders at least;
for joists, you just use the tables).
This month we'll go into the raw
strength of a beam; next month we'll
consider shear, deflection, and
All beams, whether wood, steel,
concrete, or composite, have five principal
properties of interest to the structural
engineer: support configuration,
cross-section, material, length, and
load. From these five properties, we
can usually determine whether the
beam will do the job.
All these properties apply to the
wood members found