ECS221L17

# ECS221L17 - 2 forces constrain 1 point 2n forces constrain...

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Analysis of Structures Truss . A structure designed to support load. Composed of straight two force members connected at joints.

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… more Frame . A structure designed to support load. Composed of members of which at least one is multi-force.
… more Machine (mechanism) . A structure used to transmit or modify load. Composed of members of which at least one is multi-force.

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The Truss Straight two force members Loads applied at joint connections No moments transmitted at joints Tension or compression only!
… more A space truss is 3-D while a planar truss is 2-D. A truss is just rigid if removal of any one of its members destroys rigidity. If it does not, then truss is over-rigid .

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Theorem For a just-rigid planar truss the number of members m is 2n-3 where n is the number of joints.

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Unformatted text preview: 2 forces constrain 1 point 2n forces constrain n points 2n forces, m from members + 3 from supports Examples. m = 2n - 3 n = 3 , m = 3 n = 6 , m=9 m = 2n-3 is necessary, not sufficient! C truss not rigid! Simple Trusses Triangle is simplest just rigid planar truss. Simple trusses constructed by adding 2 members , 1 joint to basic triangle. Method of Joints Obtain internal forces in members and support forces. Step 1. Obtain support forces by applying equilibrium to entire truss. Step 2. Obtain internal forces by applying equilibrium to each joint. Special Cases 1. 2. A E B C D AE=AC AD=AB A B C D AC=0 AD=AB more 3. 4. A B C D P AC=P AD=AB A D B AB=0 AD=0...
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## This note was uploaded on 04/02/2012 for the course ECS 221 taught by Professor Macnamara during the Fall '08 term at Syracuse.

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ECS221L17 - 2 forces constrain 1 point 2n forces constrain...

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