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.





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


useful for atrium skylights and other short and medium span

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

(scale visualization model)

click image to enlarge


Back to Knowhere

Page 139 - Building stability - Tri-5 spaceframe

home   sitemap   products   Polywood   .networks   contact us   Knowhere   3Doodlings