Square spaceframe lattices 
. 
Square
spaceframe lattices are comprised of a pair of twoway square grid layers that
are 
staggered relative to one another. To repeat, this spaceframe,
called Square2, 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 crosssections.
The 
. 


click image to enlarge 
Fig. 250  Staggering of square 
Fig. 251  Square2 spaceframe (red) 
grid layers 
sliced out of the octet truss 

. 
struts
comprising the web members of the spaceframe form oblique angles with the 
staggered grids thereby triangulating the structure. 
. 
Square2 spaceframe: (self dual
tessellation  twoway square grid staggered over twoway 
square grid) 
. 
The
Square2 lattice design is the most common spaceframe structure in use
today. 
. 



click image to enlarge 
a) outer grid (looking
down) 
b) inner grid (looking up) 
c) strut diagram 
. 
Fig. 252  Square2 spaceframe
[demonstration model built from small
triangles (ST) ]* 
* can also be built with IT or LT 

. 
The
Square2 cell is inherently unstable due to the square shaped openings in
the grids. 
. 



Fig. 253  Stability analysis of 
the Square2 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 

