Is it fair to call a cable-stayed bridge just a less complicated and, more importantly, cheaper version of suspension bridge?
Were suspension bridges basically just extremely overbuilt in the past 150 years? Or have modern materials & computer modeling allowed for cable-stayed construction to be a reality?
Can cable-stayed be used for extremely long spans and, therefore, are suspension bridges on their way out or will they still have to be built?
At last! A bridge question! Here is a pretty good overview of cable stays. I believe suspension bridges just cannot compete economically with cable stays. The fact that you can build the superstructure out of precast concrete segments means you can build them faster and don’t have to paint them. Painting is a huge investment, bridges like the Mackinac and Golden Gate are essentially continuously being repainted. The precast concrete segments really weren’t practical until the 1970s when post tensioning technology began to flourish.
For what it’s worth, I think suspension bridges are more aesthetically pleasing than cable stays. Here is the most beautiful bridge ever built.
I don’t know if I would call the cable stays less complicated, any major bridge is a pretty complex piece of engineering. But cheaper- definitely.
The longest cable-stayed bridge is the Tatara Bridge in Japan, with a center span of 890 m. This compares pretty well with the older generation “extremely long span” bridges, like the Verrazano Narrows Bridge at 1298 m.
OTOH, the current longest suspension bridge is the Akashi-Kaikyo Bridge, also in Japan, with a center span double in size of the Tatara at 1990 m. This was built roughly at the same time as the Tatara, which implies suspension bridges aren’t obsolete yet.
There is still a niche for suspension bridges, over very long spans. There is a limit to the angle at which the cable stays can effectively reach and still support the deck vertically, putting a maximum spacing between piers that does not apply to a suspension type.
They can both be beautiful, IMHO - there are some simply-functional cable-stayeds, and the Golden Gate Bridge is a suspension type.
>> Is it fair to call a cable-stayed bridge just a less complicated and, more importantly, cheaper version of suspension bridge?
They are different things altogether. In a suspension bridge you have roadway spans hanging from the suspension cable. you could remove a piece of roadway and not affect the bridge that much (I am simplifying but you get the idea). A cable stayed bridge works by the force of the cables pulling up and the roadway next to the bridge pushing away from the tower. You have a compression force on the platform which you do not have in a suspension bridge. Remove a section of the platform and the rest will not stay in place but will move towards the closest tower.
Thanks MSU for those links. I’m a bridge lover too, my dad was a structural engineer and bridges have a special place in my heart.