Advent of Trusses and Structural Analysis

[Qshake]

All,

I've often heard, but have yet to read or otherwise quantify dates truss design. Some information I seen indicates that various early trusswork was done prior to actual structural analysis. More of a craft of capentry rather than one of science. Can anyone place any dates on these two items, trusses and mechanics? I suspect that mechanics might have been around since the late 15th century but definitely in the 16th century. Any other information?

 

[JAE]

Qshake, that's an interesting question. I couldn't find any specific reference to truss design origination but the earliest use of trusses that I could visualize would possibly be in ship-building. The cross frames within the body of a ship are "truss-like".

The oldest trusses I've ever seen were inside an old convent built in the late 1800's but I'm sure trusses were used prior to that.

 

[eureka]

See: 'Indeterminate Structural Analysis', by J. Sterling Kinney.
Chapter 1: A Brief History of Structural Theory
Section: The Early Period (1493-1687)
'Andrea Palladio (1518-1580) an Italian architect, is believed to have first used trusses, although his designs were not the result of rational analyses. Prior to this development all construction, except solid masonry, was composed of beams, columns arches and domes.

 

[GregLocock]

Hmm. I think wooden bridges, formwork and scaffolding would be earlier examples of truss-like structures (depending on how you define trusses - how about repeated bays of thin elements taking loads primarily in tension and compression?). Although I guess most early bridges were just beams in bending.

Having said that it's nice to see Palladio mentioned!

Cheers

Greg Locock

 

[ludvik]

As eureka points out, Palladio was the first to write anything about trusses in his "Three Books on Architecture".

Trusses were first seriously used in cathedral construction. Cathedrals demanded long spans to support the roof, and trusses fitted the bill.

But cathedrals builders developed truss technology, they did not invent them. It is hard to say exactly when the very first trusses were built, but we do know that ordinary roof structures for barns and the like used a simple roof truss design as far back as the late dark ages (~900AD).

I'm not sure when they figured out how to analyze a truss...If I had to guess it would have been around the time of Da Vinci.

Michael

 

[GregLocock]

I _think_ it would be a bit later. Galileo got in a right muddle over the cantilevered beam, and if you can solve the beam then a truss would be easy. He was born about 100 years after Da Vinci.

Cheers

Greg Locock

 

[Qshake]

Well, this is all great information...keep it coming. BTW, I'm not too interested in analyzing trusses just the first use of them.

Qshake

 

[ludvik]

I recommend you have a look at Three Books on Architecture. It was a ground breaking classic at the time, and is very interesting in historical terms.

A modern engineer will look at some of the 16th century trusses and pick them to pieces. They had all kinds of members in them which didn't need to be there, and awful joint details. But they worked. And they developed into the railroad trusses of the late 18th and 19th century.

The signiature Howe, Warren, and Pratt trusses which are common currency today were all invented by engineers during this time, primarily for use in railroads. There were also tonnes of other standard designs like the lattice truss and Whipple truss which have long fallen out of use for a variety of reasons.

I did a big historical study of all of the timber truss bridges in my home state in Australia, which included a good introduction to the historical development of trusses...I might be able to get you a copy of the report if you are interested. (The report won a couple of awards and I like to show it off)

Michael

 

[austim]

Hi, Ludvik

That sounds like a very interesting report. Could you please give us a Title, Date and Author reference. (Then I might be able to find it at Monash or Melbourne Uni libraries ??)

 

[ludvik]

Hi austim,

The report was entitled "Heritage Study of All Timber Truss Road Bridges in NSW", June 1999, by McMillan Britton and Kell prepared for the NSW RTA.

Though I doubt you'll be able to find it in the library. We did the study for the New South Wales Roads and Traffic Authority.

btw: are you or do you know Tim Wilkinson?

Michael

 

[austim]

Hi, ludvik.

No, I am not Tim Wilkinson. There must be more Tims in Aus than I knew of