the vierendeel @ richards medical

i like aalto's butterfly truss.

though, i would hate to calculate a truss!

"Two 45-ton horizontal jacks were used at each end, at the points of contact of the strut and the harness, to fit the brace against the legs."

I'm unclear on how the jacks may have been employed. It may have been necessary, due to the weight of each leg of the arch (with the added weight of the cranes), to spread the legs to their correct final positions, prior to the addition of the remaining segments ?

It is always a pleasure to read accounts of the mechanics of construction.

Chapter Four of Condit's volume on nineteenth-century "Building Art" begins with this paragraph:



"The same demands that led to the substitution of iron for wood in buildings lay behind its use in bridges-strength, durability, and fire resistance. Its great advantages over stone masonry are its high tensile strength and elasticity, physical properties non-existent for practical purposes in unreinforced masonry, and the ease with which it can be worked. It was the railroad that made the nineteenth century the age of iron, and the rapid growth of the new system of transportation made the iron bridge a matter of necessity from the second decade of railroad construction. Since wood has certain physical properties comparable on a lower scale to those of iron, the bridge builders took over the techniques and forms of timber construction with little change. The chief difference was a saving of material made possible by the use of thin rods for members subjected only to tension. The approach of the American builder was again characterized by that forthright anti-traditional empiricism which always seemed to astonish the European. In the United States the criteria of adequate construction were always pragmatic, seldom either scientific or aesthetic: the minimum of material consistent with safety; the most rapid and efficient means of construction; design for expansion and relocation rather than permanence. It was a simple program, and if it seldom produced finished structural art, it could at least satisfy the demands of immediate mechanical utility. The great defect in it was that the science of ferrous metallurgy in the United States lagged far behind the requirements of construction. Carelessness and irresponsibility too often characterized the rapid expansion of wealth. The consequence was that the history of the iron bridge in the nineteenth century was to a melancholy extent a history of disaster. By 1875, however, the methods of science were applied to the techniques of construction, and the series of tragedies were eventually brought to an end."


Makes you want to read on, no ?

re; horizontal jacks
sdr, i guess what you said is exactly why the horizontal jacks were employed. open the arch legs enough to place keystone segment of the arch and let the legs fall into place and compress. so, essentially making the said truss work like a column...
quite ingenious and simply elegant thinking.

Interesting that it wasn't the original plan. I guess the three- or six-inch cables were to be used at or near the outer face of the arch legs -- outside the skin, or within ? -- pulling them more nearly upright ?

From Condit:

Town



Fink




Holz, I was always tickled by the (perfectly justified) asymmetry at the very corner of that rigorously symmetrical assembly:

These are all grat links, thanks guys!..

isnt it a bit late to be looking into new truss designs at this point? I mean, isnt the review, like, this friday or something??

Just kidding, you got plenty o' time. And they never stick with the schedule anyway, I'd put $$ down that they put it off till monday.

i like the vierendeel, but it's not a truss.

Sure it is -- my 10-year-old nephew wrote the definition !

The Vierendeel truss is a truss where the members are not triangulated but form rectangular openings, and is a frame with fixed joints that are capable of transferring and resisting bending moments. Regular trusses comprise members that are commonly assumed to have pinned joints with the implication that no moments exist at the jointed ends. This style of truss was named after the Belgian engineer Arthur Vierendeel[10], who developed the design in 1896
The beauty of this type of truss is that there is no diagonal bracing, the creation of rectangular openings for windows and doors is simplified and in cases the need for compensating shear walls is reduced or eliminated.
After being damaged by the impact of plane hitting the building, parts of the framed curtain walls of the Twin Towers of the World Trade Center resisted collapse by Vierendeel action displayed by the remaining portions of the frame.

sorry SDR, but a Vierendeel Truss is not a truss, but a rigid frame.

Vierendeel trusses must be analysed as rigid frames.

Makes sense to me. So, it's classified with the trusses based on its *function*, rather than on its inherent *form*. . .

i think it's the opposite actually.

concrete does not work in tension, compression great, tension not so great...you need both in a truss.

Truss function: capable of supporting loads like a simple, or a cantilevered, beam but with greater efficiency

Truss form: incorporates diagonal members which correspond to load paths

got it.

Trusses: pinned connections
Frames: rigid connections

so the diagonal member follow in the definition of a truss, since the joints are shear only.

er, right?

Right. So the rigid frame acts in a wholly different way from the truss.

Is "moment frame" a correct term for the Vierendeel "truss" ?

I'd say yes.

Right on!

Good. Now, let's determine the difference between a Honda, and a Toyota.

Poor ff33 isn't getting many answers to the original question. . .

I always liked the trusses at Blue Hill at Stone Barns.

So I'm a wise guy.

"There is nother absurder than the Vierendeel Girder"

Word around the campfire is this was the nickname during construction of Richards.

*nothing (not nother)..