In addition to the shear deformation, another difficult problem
that arises in castellated members is the second moment of area that
varies periodically from that of an “I-section” shaped beam (i.e. with
no openings) to that of a “two-tee-section” shaped beam (i.e. with
openings). This unique nature makes the castellated beam more like a
sandwich beam, in which the two tee sections behave as the outer
layers of the sandwich beam to take the bending moment, whereas
the discontinuous parts of the web behave as the middle layer of the
sandwich beam to take shear forces.
that are normal to the deflected beam axis. In the latter the outer layers of
the sandwich beam are assumed to deform according to Bernoulli's
hypothesis and the cross section of the middle layer behaves as a shear