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Unformatted text preview: 05Ch05.qxd 9/24/08 4:59 AM Page 425 425 SECTION 5.6 Design of Beams t Problem 5.6-18 A horizontal shelf AD of length L 915 mm, width
b 305 mm, and thickness t 22 mm is supported by brackets at B and C
[see part (a) of the figure]. The brackets are adjustable and may be placed
in any desired positions between the ends of the shelf. A uniform load of
intensity q, which includes the weight of the shelf itself, acts on the shelf
[see part (b) of the figure].
Determine the maximum permissible value of the load q if the allowable
bending stress in the shelf is sallow 7.5 MPa and the position of the supports is
adjusted for maximum load-carrying capacity. A
B D C b L
(b) Solution 5.6-18
L b 915 mm sallow 2 12) Substitute x into the equation for either M1 or |M2|:
305 mm t 22 mm
Mmax 7.5 MPa MOMENT DIAGRAM qL2
sallow S sallow a 2 12) Eq. (1)
6 Eq. (2) Equate Mmax from Eqs. (1) and (2) and solve for q:
3L2(3 Substitute numerical values:
For maximum load-carrying capacity, place the
supports so that M1 |M2|.
‹ length of overhang
4x) Solve for x: x |M2| L
2 1) qx2
2 qmax 10.28 kN/m ; ...
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This note was uploaded on 12/22/2011 for the course MEEG 310 taught by Professor Staff during the Fall '11 term at University of Delaware.
- Fall '11