25 May 2010

Titanium bridge contest winner

The University of Akron's Blue Team has been announced as the winner of the US Defense Metal Technology Center's contest to design a titanium footbridge. This is proposed to be a real bridge in Akron, Ohio (as yet unfunded), although the main aim of the contest is to try and provoke interest in the structural use of titanium, ultimately to "demonstrate the versatility of titanium and make the metal more affordable in lifesaving military armament".

The winning design is perhaps the least elegant of the five finalists, although it is at least practical, unlike the runner-up, which demonstrates almost everything which is wrong about the present infatuation with digitally-developed geometry.

University of Akron Blue Team

Ball State Dept of Architecture and Institute for Digital Fabrication

First honorable mention
University of Akron Gold Team

Second honorable mention
Kent State

Third honorable mention
Miami University


Jason Salonga said...

I'm not sure if I would even consider the winner to be practical. Based on the low resolution rendering, the primary load paths are not clear to me. Are those diagonal members load-carrying? They seem to fade away toward the left. The span-to-depth ratio seems low, which brings me to question whether the cable-stays are even needed. There's lots of connections to deal with at the intersection of the cables and tower. They may also need a tie at the bend of the tower legs to avoid bending moments. I suppose a closer look at the preliminary drawings would answer some of my questions.

The Happy Pontist said...

See http://www.ohio.com/multimedia/photo_galleries/viewer?galID=94540164&storyID=94559069 for more photos including of a physical model. The diagonal elements appear to be cladding features. The deck is therefore a slim beam or slab, with a covered walkway on top which is not part of the main span structure. Clearly, a truss or beam structure would be able to bridge this span, but I don't know enough about titanium to know how it can be most efficiently assembled.

Jason Salonga said...

Thanks for the link. The model makes a little more sense now. I see they have the stays extending much farther out into the spans, which is probably a good idea. Picture 5 shows that they had to attach some additional piece to the tower to connect to the stays. Hopefully they can deal with that connection much more elegantly in final design.You're right, connection design and assembly for titanium must be quite different than for structural steel.