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Unformatted text preview: 05Ch05.qxd 9/25/08 2:29 PM Page 483 483 SECTION 5.12 Beams with Axial Loads Problem 5.12-10 A flying buttress transmits a load P 25 kN, acting
at an angle of 60° to the horizontal, to the top of a vertical buttress AB
(see figure). The vertical buttress has height h 5.0 m and rectangular
cross section of thickness t 1.5 m and width b 1.0 m (perpendicular
to the plane of the figure). The stone used in the construction weighs
y 26 kN/m3.
What is the required weight W of the pedestal and statue above the
vertical buttress (that is, above section A) to avoid any tensile stresses
in the vertical buttress? Flying
A A t
B Solution 5.12-10 h
t B Flying buttress FREE-BODY DIAGRAM OF VERTICAL BUTTRESS CROSS SECTION
A bt S 12
6 1.5 m2 (1.0 m)(1.5 m) 1
(1.0 m)(1.5 m)2
6 0.375 m3 AT THE BASE
N W + WB + P sin 60°
W + 195 kN + (25 kN) sin 60°
W + 216.651 kN M (25 kN) (cos 60°) (5.0 m) (Pcos 60°) h
62.5 kN # m TENSILE STRESS (EQUAL TO ZERO)
P 25 kN h 5.0 m t 1.5 m N
S st b
b 1.0 m 2 width of buttress perpendicular to the figure g
WB 26 kN/m weight of vertical buttress
195 kN 1.5 m
or 3 bthg 62.5 kN # m W + 216.651 kN
W W 33.3 kN + 0.375 m3 216.651 kN + 250 kN
; 0 0 ...
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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