As the unstable unit cell shows, the lattice lacks stability in the


diagonal direction.  It is vulnerable to twisting, or torsion, forces if

its perimeter is not supported at all four corners.  It is best used for

short spans where only a few modules are required, or where the

loading is uniform across the structure and perpendicular to its

plane.  The figure to the right shows how this lattice can be twisted

into a curved hyperbolic parabola, or hypar, shape by making use

Fig. 254 - Bus stop

of its lack of torsional stability.

with hypar cover


In a variation of the Square-2 design, called Square 2a, the square checkerboard pattern

of the grids is rotated forty-five degrees so that the perimeter slices the outermost squares

diagonally in half.  This variation is useful for matching the angled edge of a building.





click image to enlarge

a) outer grid  (looking down)

b)  strut diagram

c)  Kiosk with Square-2a roof


Fig. 255 - Square-2a spaceframe  [demonstration model made with small triangles (ST) ]


As with the triangular spaceframes, the depth of square spaceframes can be increased to

increase their spanning or load bearing capacity,  When the depth/module ratio is equal to

0.707 all of the struts comprising the structure are the same length.

side view




depth/module = .707

depth/module = .707

depth/module = 1.26

top view




a) w/ small triangles (ST)

b) w/ large triangles (LT)

c) w/ isosceles triangles (IT)

click image to enlarge

Fig. 256 - Square-2 unit cells with varying depth/module ratios  (demonstration models)


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Page 143 - Building stability - Square-2 spaceframe

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