Step 6: Building the deck
Once the bridge was in the air, the garden variety work of deck building got under way. 2x8x16 lumber for decking, 2x4x16 for the hand rails, 5/4x6x16 decking for the facing boards on the handrail system.
The handrail system is an integral part of a suspension bridge - the two handrails form the trusses that provide most of the rigidity to the bridge. Without the trusses, the bridge is an elevated snake. With them, it is incredibly stable.
To make the handrails into trusses, we placed cut-to-length 2x4s from the top of one handrail support to the bottom of the next, working our way from both ends to the middle. The bridge is all but unusable without adequate trusses - witness the failure of the Tacoma Narrows bridge, due entirely to insufficient stiffness.
http://www.wsdot.wa.gov/tnbhistory/Connections/connections3.htm
Entirely unexpected was the genuine beauty of the bridge. Through what can only be sheer luck, the finished bridge is simply magnificent.
The handrail system is an integral part of a suspension bridge - the two handrails form the trusses that provide most of the rigidity to the bridge. Without the trusses, the bridge is an elevated snake. With them, it is incredibly stable.
To make the handrails into trusses, we placed cut-to-length 2x4s from the top of one handrail support to the bottom of the next, working our way from both ends to the middle. The bridge is all but unusable without adequate trusses - witness the failure of the Tacoma Narrows bridge, due entirely to insufficient stiffness.
http://www.wsdot.wa.gov/tnbhistory/Connections/connections3.htm
Entirely unexpected was the genuine beauty of the bridge. Through what can only be sheer luck, the finished bridge is simply magnificent.
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I'm an architect and I can say that this bridge really brought something special to the property.
Bravo!
Very nice!
That is a lot of work, but the feeling of getting the job (well) done is priceless.
Greetings,
Just to be clear, though: there is no tension-adjusting mechanism on the vertical stays? You calculated the length of each stay assembly at each joist, built them to that length, and installed them that way without any further fine-tuning possible, is that right?
It obviously worked great, but what would happen if one of the assemblies was slightly off-length? And how do you deal with creep (stretch) in the suspension cables and vertical stays?
I have been thinking about all the projects on this site, and all the things people do to make things, and I think that, large or small, it is the making, the creating, that is important.
I had an opportunity, and need even, the requisite skills and enough help and money to make it happen. There are many projects here for which I entirely lack the skills to make happen, and to attempt those projects would be beyond me.
It also helps, in a long project like this, that I am at my best with a deadline and when I obsess, both of which were true.
there are so many cool projects on this site & this is one is one of those that keeps yah seeing & doing more...
I have a blog http://casperdub.blogspot.com (scrapbook) of my work which you might find interesting (the folding, sideways sliding kids-scale chairs video begins automatically part way down the blog)
perhaps I should enter something here...
this is my first time ever commenting on this site...
thanks for sharing the process.
forgive me my English I'm from Belgium.
If I had pulled in the catenary cables without any other structure attached, it would not have been an issue and I could have used a continuous cable. The problem is that installing the deck from the in-air cable would have been all but impossible.
I could have used the same process of floating the bridge to the site and then taking the catenary cables over a saddle to each anchor and then raising the substructure, but then the towers would have had to have a greater "bury" and that would have reduced the max sag, which would have increased tensions and loading everywhere else in the bridge, or would have required longer tower legs, and they were as long as I could comfortably handle as it was!
grts