# space trusses - TAM 210/211 Engineering Mechanics: Statics...

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1 Lecture 18 Structures: Space Trusses Stephen D. Downing Mechanical Science and Engineering © 2001 - 2008 University of Illinois Board of Trustees, All Rights Reserved TAM 210/211 Engineering Mechanics: Statics TAM 210/211 - Lecture 18 © 2008 Stephen Downing, University of Illinois at Urbana-Champaign, All Rights Reserved 1 of 13 Planar Trusses A planar truss is a 2 dimensional structure made up of straight and slender bars held together on the ends by frictionless pins. Each joint has 2 equations of equilibrium. Each joint 0 F F Y X = = Basic shape is a TRIANGLE P = no. of pins (joints) M = no. of members; m = 2p - 3 for a simple truss as on left. 2 equations; 0 F = 2 unknowns; F BE , F DE AB C D E At point E

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2 TAM 210/211 - Lecture 18 © 2008 Stephen Downing, University of Illinois at Urbana-Champaign, All Rights Reserved 2 of 13 Static Determinacy e determinat statically 3 p 2 7 m , 5 p = = = ate indetermin statically 3 p 2 8 m , 5 p > = = unstable 3 p 2 6 m , 5 p < = = TAM 210/211 - Lecture 18 © 2008 Stephen Downing, University of Illinois at Urbana-Champaign, All Rights Reserved 3 of 13 Example
3 TAM 210/211 - Lecture 18 © 2008 Stephen Downing, University of Illinois at Urbana-Champaign, All Rights Reserved 4 of 13 Space Trusses A B C D E F G A B C D A nonplanar truss is called a space truss or a space frame. Each joint has 3 equations of equilibrium not 2 as in a planar frame Each joint 0 F F F Z Y X = = = Basic shape is a TETRAHEDRON P = no. of pins (joints) M = no. of members; m = 3p - 6 for a simple truss.

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## This note was uploaded on 04/08/2008 for the course TAM 210/211 taught by Professor Downing during the Spring '08 term at University of Illinois at Urbana–Champaign.

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space trusses - TAM 210/211 Engineering Mechanics: Statics...

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