Tri-5 spaceframe:  (three-way large and small triangular outer grid staggered over three-

                              way hexagonal inner grid)

.

The Tri-5 spaceframe lattice is basically the same as Tri-3 except that three struts are also

removed periodically from the outer layer so as to form a grid of large and small triangles.

.

tri-5_spaceframe.jpg

tri-5_spaceframe.jpg

tri-5_spaceframe.jpg

click image to enlarge

a) outer grid

b) inner grid

c) strut diagram

.

Fig. 241 - Tri-5 spaceframe  [demonstration model constructed from small triangles (ST) ]*

 * can also be constructed from RT, LT, or IT
.

The loss of the struts in the outer layer further destabilizes the structure as shown in the

following unit cell analysis.

 

Fig. 242 - Stability analysis

of the Tri-5 unit cell

 

(demonstration model)

click image to enlarge

 

a)   M = 24   J = 12

b)  stabilized by

 

24 < 3 ( 12 ) - 6

plate action

 

unstable, need +6 M

(2 plates - red, blue)

 

.

Fig. 242 b) above shows that the spaceframe can stabilized by inserting panels or skylights

into the large triangular openings of the outer layer (shown in blue) and the hexagonal

openings of the inner layer (shown in red).

.

Due to the openness of the design, the Tri-5 spaceframe is

patio_table.jpg
useful for atrium skylights and other short and medium span
applications.
 

Fig. 243 - Patio table with Tri-5 spaceframe sunshade  ►

(scale visualization model)

click image to enlarge

 

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Page 139 - Building stability - Tri-5 spaceframe

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