Square spaceframe lattices

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Square spaceframe lattices are comprised of a pair of two-way square grid layers that are

staggered relative to one another.  To repeat, this spaceframe, called Square-2, can be

sliced out of the octet truss parallel to the 100 plane.  Doing so splits the octahedra

embedded in the lattice in half thereby exposing their square shaped cross-sections.  The

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staggered_two-way_grid.jpg

square-2_spaceframe.jpg

click image to enlarge

Fig. 250 - Staggering of square

Fig. 251 - Square-2 spaceframe (red)

grid layers

sliced out of the octet truss

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struts comprising the web members of the spaceframe form oblique angles with the

staggered grids thereby triangulating the structure.

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Square-2 spaceframe: (self dual tessellation - two-way square grid staggered over two-way

                                      square grid)

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The Square-2 lattice design is the most common spaceframe structure in use today.

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square-2_spaceframe.jpg

square-2_spaceframe

square-2_spaceframe

click image to enlarge

a)  outer grid (looking down)

b)  inner grid (looking up)

c) strut diagram

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Fig. 252 - Square-2 spaceframe [demonstration model built from small triangles (ST) ]*

 * can also be built with IT or LT

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The Square-2 cell is inherently unstable due to the square shaped openings in the grids.

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square-2_spageframe.gif

square-2_spaceframe.gif

Fig. 253 - Stability analysis of

the Square-2 unit cell

 

(demonstration model)

click mage to enlarge

 

a)  M = 11    J = 6

b)  M = 12    J = 6

 

11 < 3 ( 6 ) - 6  unstable

12 = 3 ( 6 ) - 6  stable

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Page 142 - Building stability - Square spaceframe lattices

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