Rectangular spaceframe lattices |
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Rectangular spaceframe lattices are comprised of two rectangular grid
layers that are |
staggered relative to each other. Diagonal struts connect the hubs
of each layer thereby |
triangulating the web. One variation of this spaceframe, called
Rec-2, is identical to the |
one that
can be sliced out of the octet truss parallel to the 110 plane. |
. |
 |
◄ Fig. 265 - Staggered |
 |
rectangular grids |
|
Fig. 266 - Rec-2 spaceframe |
(green) sliced out of |
the octet truss ► |
|
. |
Rec-2
spaceframe: (two-way rectangular outer grid staggered over
two-way |
rectangular inner grid) |
. |
The
Rec-2 spaceframe is similar in structure to Square-2 except for the
rectangular pattern |
of its
grids. |
 |
 |
 |
click image to enlarge |
a) outer grid |
b) inner grid |
c) strut diagram |
. |
Fig. 267 - Rec-2 spaceframe
[demonstration model built from RT (red)
and ST (blue)* |
|
* can
also be built with LT and IT to increase depth |
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Like
Square-2, the unit cell of Rec-2 is inherently unstable. Therefore
the framework lacks |
torsional stability.
Adequate perimeter support must be provided. It is useful for
vertical |
glazing frameworks subject to inward and outward acting wind loads that
are of equal |
magnitude. |
. |
|
 |
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Fig. 268 - Stability analysis
|
M = 11 J = 6 |
of Rec-2 unit cell |
11 < 3 ( 6 ) - 6 |
RT (red), ST (blue) |
unstable, need +1 M |
(demonstration model) |
click image to enlarge |
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to Knowhere |
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Page 147
- Building stability - Rectangular spaceframes |
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