Timothy A. Philpot - Mechanics of materials _ an integrated learning system-John Wiley (2017)

ExERcISES
m9.9 Five multiple-choice questions involving the calculation
of Q for built-up beam cross sections.
m9.11 Four multiple-choice questions pertaining to shear flow
in built-up beam cross sections.
FIGURE m9.11
FIGURE m9.9
m9.10 Five multiple-choice questions pertaining to shear flow
in built-up beam cross sections.
pRoBLEmS
FIGURE m9.10
p9.26 A rectangular beam is fabricated by nailing together three
pieces of dimension lumber as shown in Figure P9.26. Each board
has a width b = 4 in. and a depth d = 2 in. Pairs of nails are driven
along the beam at a spacing s, and each nail can safely transmit a
force of 120 lb in direct shear. The beam is simply supported and
carries a load of 800 lb at the center of a 9 ft span. Determine the
d
d
d
b
s
FIGURE p9.26
maximum spacing s (along the length of the beam) permitted for
each pair of nails.
p9.27 A wooden I beam
is fabricated from three
pieces of dimension lumber
as shown in Figure P9.27.
The cross-sectional dimensions
are b f = 90 mm, t f =
40 mm, d w = 240 mm, and
t w = 40 mm. The beam will
be used as a simply supported
beam to carry a concentrated
load P at the center
of a 5 m span. The wood has
an allowable bending stress
of 8,300 kPa and an allowable
shear stress of 620 kPa.
t f
dw
t f
The flanges of the beam are fastened to the web with screws that can
safely transmit a force of 800 N in direct shear.
tw
s
b f
FIGURE p9.27
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