1
1.9 k
1.9 k
V
M
12.67 k-ft
7.25”
3.5”
1.5”
1.5”
1.5”
8”
y
ˆ
=4.02”
Ix = 316.1 in4
Figure 3b
1.5”
Figure 3c
x
15 in
y
65” tall by 80”
wide elliptical
bar stock
Figure 3a.
O
25.5 in
29” wide by
44” tall cut-out
Note: No aids are allowed for part 1. One side of a letter sized paper with notes is allowed
during part 2, along with a silent, non-programmable calculator. There is a reference chart for
part 2, shown on page 2.
Clearly show your work and answer.
Part 1) Worth 5 points (conceptual questions)
Part 2) Worth 45 points
(NOTE: The cross section basic shapes, holes, dimensions and
reference origin can and will be changed for the quiz! The beam
section information and diagrams will be provided.)
For the cross section shown in Figure 3a complete
the chart to find:
a) The location of the centroid of the shape from the reference
origin given.
b) The moment of inertia about the x axis, Ix, of the section [or
about the y axis, Iy]
For a 20 ft long beam with the following cross section properties
in Figure 3b, and the shear and bending moment diagrams shown
in Figure 3c find:
c) The maximum bending stress, fb, about the x axis
d) The required shear capacity of the nails, F, for the top [or
bottom] connected piece if the pitch spacing, p, is 4.5 in..
Answers – Not provided on actual quiz!
a)
x
= -13.6 in,
y
ˆ
= 30.3 in b) Ix = 903951 in4 [or Iy = 1586156 in4]
c) fb = 2.28 ksi d) F ≥ 281.3 lb (Qtop = 20.8 in2 ) [or 265.3 lb (Qbottom = 39.24 in2)]
A (in2)
x
(in)
Ax
(in3)
y
(in)
Ay
(in3)
Ix (in4)
dy (in)
Ady2 (in4)
ellipse
4084.1
-14.5
-59219
32.5
13273.2
1078450
hole
