The Elastic Vector Method

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The Elastic Vector Method

• By T. Bart Quimby, P.E., Ph.D.
• Quimby Associates

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Elastic Method
Move Horizontal Force to Center of Bolt Group
Break force into its components
Move Vertical Force to Center of Bolt Group
Combine the Two Moments into One
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Elastic Method
Find Bolt Stresses due to Moment
fy Py/(Abnb)
fmi M ri / J fmxi fmi dyi/ci fmyi fmi
dxi/ci
fx Px/(Abnb)
Find Bolt Stresses due to Vertical Force
Find Bolt Stresses due to Horizontal Force
Bolt stresses due to Moment are perpendicular to
radial lines from the center of the bolt group
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Elastic Method
The resultant stress in each fastener equals the
vector sum of the stresses applied to it.
fi sqrt(fyi fmyi)2 (fxi fmxi)2 Pi fi
Ab
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Elastic Method

• Good
• Very easy and straight forward use of Mechanics
• Not so Good
• Very conservative
• Not consistent with test results resulting in a
  widely variable factor of safety