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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Trusses
Copyright ©2011 by Pearson Education, Inc.
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Copyright ©2011 by Pearson Education, Inc.
All rights reserved.
Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Copyright ©2011 by Pearson Education, Inc.
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Basics & Assumptions
• Trusses are composed of
Members (long & slender)
Joints (where members connect)
Forces are only at Joints
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Copyright ©2011 by Pearson Education, Inc.
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Assumptions
• Pin connections to members at joints.
• All loads are at joints.
• All members are rigid and straight.
Members are considered two-force members
Either in tension (pulling at joint),
OR in compression (pushing at joint)
Assume tension if unknown.
• Force in member is along the member
Copyright ©2011 by Pearson Education, Inc.
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Copyright ©2011 by Pearson Education, Inc.
All rights reserved.
Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Copyright ©2011 by Pearson Education, Inc.
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Example
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Joint B
Joints
• Tensions Pulls
• Compression Pushes
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Section
around B
• Tensions Pulls
• Compression Pushes
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Joints & Members
• Tensions Pulls
• Compression Pushes
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Two approaches to find forces
in members • Method of Joints
ΣFx=0
ΣFy=0
OR
• Method of Sections
ΣFx=0
ΣFy=0
ΣMz=0
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Method of Joints
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Copyright ©2011 by Pearson Education, Inc.
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Copyright ©2011 by Pearson Education, Inc.
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Zero Force Members
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Zero Force Members
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Simplified Truss Design
w/o Zero Force Members
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Can you spot the
Zero Force Members ?
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Find the Zero force members
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Copyright ©2011 by Pearson Education, Inc.
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Copyright ©2011 by Pearson Education, Inc.
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Method of Sections
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Internal forces
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Method of Sections:
3 unknowns Max
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Machines/Frames
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Copyright ©2011 by Pearson Education, Inc.
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Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Copyright ©2011 by Pearson Education, Inc.
All rights reserved.
Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Copyright ©2011 by Pearson Education, Inc.
All rights reserved.
Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Copyright ©2011 by Pearson Education, Inc.
All rights reserved.
Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Copyright ©2011 by Pearson Education, Inc.
All rights reserved.
Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Copyright ©2011 by Pearson Education, Inc.
All rights reserved.
Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler
Copyright ©2011 by Pearson Education, Inc.
All rights reserved.
Statics and Mechanics of Materials, Third Edition
Russell C. Hibbeler