Wednesday, February 11, 2009

Two Bridges - Erasmus and Ling-Tie

A guest post by Jeff Perren that originally appeared at his Shaving Leviathan blog.
It's easy to see why the locals call the Erasmus Bridge in Rotterdam "The Swan." But it may be too timid a metaphor. The structure's grace and beauty far outshine that creation of nature.

(Photo by Lars Mathiassen)
    The Erasmus is a design known to bridge aficionados as 'cable stayed'. A series of thick, ultra-strong steel strands reach from the tip of the pylon (the swan's 'neck') to the roadbed below, looking like nothing so much as a set of taut piano wires. Like a cross-beam on a swinging gate, those cables resist the downward forces on the road.
    Designed by Ben van Berkel and completed in 1996, the bridge is 800 meters (2,600 feet) long, about 10% of which raises to allow ships to pass under.
   
    Bridge building has undergone something of a renaissance in recent decades, thanks in no small part to the work of Dr. Tung-Yen Lin of Berkeley.
    During his seven-decade career he taught or was directly responsible for numerous innovations, not the least of which was his promotion of pre-stressed concrete in building structures, now ubiquitous.   
    He used the technique in building his own home, which featured a 1,000 square foot interior span free of supporting beams. (He used the area as a ballroom to dance with his wife.) Dr. Lin passed away in 2003 at the age of 91.
    One of his most beautiful creations is the stunning Ling-Tie bridge in Nanning, China, completed after his death. Resembling a rounded harp, it provides a fascinating design variation that combines an arch with cable stayed features.



Only two out of dozens of spectacular monuments to genius, these bridges demonstrate that the great age of building is far from over. While they get less fanfare than in generations past, they remain some of man's greatest achievements.

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7 Comments:

Anonymous DenMT said...

The first bridge certainly is lovely - UN Studio does some breathtaking work, including a competition winner for Wellington's waterfront, which probably will never actually get built due to small-mindedness.

The second bridge is certainly interesting, but kind of clunky and ugly at the same time. The load paths all come to a great big dead end at the fat juncture of the arches under the bridge - all the live load of traffic under the bridge will be acting through the cables to pull those two arches together in compression, so the junction under the bridge is doing a shit load of work and isn't particularly efficient or poetic IMHO.

Compare with Calatrava, whose work PC often posts up - his projects often carefully delineate a structural principle in a sparse, efficient and beautiful way. This bridge kind of flies in the face of structural reason, to no good effect. I googled it up while responding and it appears the final product looks very different from the sketch.

Just my (traditional devil's advocate) $0.02, anyways...

DenMT

2/11/2009 04:50:00 am  
Anonymous Falafulu Fisi said...

Just Curious and I appreciate some answers.

Do architects involve in bridge design or those tasks are solely done by civil engineers?

2/11/2009 09:09:00 am  
Blogger Luke H said...

He used the technique in building his own home, which featured a 1,000 foot interior span free of supporting beams. (He used the area as a ballroom to dance with his wife.)

A 300 metre wide ballroom in a private house? Wow. :-)

It includes a 1,000-square-foot ballroom, where Professor Lin and his wife spent nearly every weekend waltzing.

OK, maybe not ...

2/11/2009 11:52:00 am  
Blogger Jeff Perren said...

"Do architects involve in bridge design or those tasks are solely done by civil engineers?"

I'm neither, but from my research, it is more often civil engineers. There are exceptions, however. Calatrava was mentioned, who is both. Lord Foster, designer of the Milau Viaduct is another example.

Peter?

2/11/2009 01:49:00 pm  
Blogger PC said...

Off the top of my head I can think of the great Pier Luigi Nervi and Frank Lloyd Wright.

But not me, not so far anyway. :)

2/11/2009 01:55:00 pm  
Anonymous PhilBest said...

Well said, Peter Cresswell. Mankind and its creations, IS the supreme level of nature. Now if we can get a few beautiful bridges for Wellington harbour and a few other strategically useful locations.......

2/11/2009 03:47:00 pm  
Anonymous LGM said...

FF

You need a chartered civil engineer to verify the design is adequate to deal with the anticipated stresses and strains, that the structure is rigid/stiff enough for all the load conditions it is expected to encounter (and some it is not), that the relevant codes/legislation/standards etc. is/are complied with. Failure modes need to be understood and dealt with as well. It's a big job usually undertaken by substantial civil engineering consultancies with substantial insurance cover.

That still leaves a lot of room to work about making the design a good (beautiful) one, even if you are not qualified to do the calcs and verify them yourself. Still, it is a really good idea to understand what is going on within your structure. DenMT's post above (where he analyses load paths) is a good example of how you should be thinking during the design phase.

Usually, if it looks good it is good. The proviso is that statement only holds true if you are good.

Civil engineering is one of the most conservative of the engineering disciplines. It is usually nowhere near as innovative as the electronics and software engineering you are well used to. The materials used are well understood and conventional. They are not especially advanced or high performance. The safety factors employed are titanic. Building these structures is really expensive (especially since they tend to be one-offs). That all tends to mean that buildings are really expensive (certainly bridges are).

It is likely there will be a revolution in building materials very soon. This is not so much for housing but will have implications for the big stuff, like towers and bridges. Hint: what happens to a sintered-powder product when the particle size is reduced by an order of magnitude?

LGM

2/11/2009 11:23:00 pm  

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