Suspension bridge design

[crazyal]

The actual walkway is made up of composite boards 1 1/2" thick. They have two PT 8' 6"x6" posts used to support the load between the i-beams. They are about 36" apart. The composite decking is sandwiched by a PT 8' 2"x4" and 8' 4"x4" on each end.

 

[crazyal]

The i-beams are "S" beams, I would have expected "W". I think they are posts for guard rails and are 5' long.

 

[crazyal]

Here's a few other random pictures.

 

[crazyal]

The ends of the two 1 1/4" cables are anchored to ledge on each end. I thought I took a picture but I guess not. It looks like it's anchored to the ledged and then they poured a cement slab on top of it.

 

[schweizer]

That is awesome! Way overkill for my purposes, but really cool none-the-less. Wow, 1 1/4" cables is huge -- extremely difficult to work with. And I thought 1/2" cable over 70' distance was heavy. My wife (and I) wouldn't like the chain-link on the sides. It also looks like they double anchored the end deadmen. Thank you very much for the pictures! More ideas....

Marcus

 

[bcp]

A little larger than yours, but sometimes the experts don't get it right.

 

[Travelover]

Off topic slightly, but for you engineer wanna-bees, this is a really fun app for iPhone or Android. This video doesn't show the construction phase, but it is easy to click and drag for wood, steel, cables and concrete. The free version is very good.

It even does real time stress analysis on the different components.

Bridge Constructor 100% Best High Score Walkthrough Truck proof HD 1080P Score 1 482 250 - YouTube

 

[lamanated]

People here are getting the side pieces from pallet racking systems and using them as bridge side railings, and running rough cut boards across them. they go for $30-40 a 15 ft length for the home depot type used.I built a utility trailer out of one.

 

[toddol1971]

People here are getting the side pieces from pallet racking systems and using them as bridge side railings, and running rough cut boards across them. they go for $30-40 a 15 ft length for the home depot type used.I built a utility trailer out of one.[/QUOTE

Where is around here. Where you from. How did you get the metal? Thanks.

 

[toddol1971]

Have you thought about using a semi flatbed. They are arched slightly. You could drive across it and it would be 40' long. I dont know if they make them 53' long or not, but it would be worth looking in to. I know it would possibly be difficult to get down there though. Maybe you could take it in there down the blm road? Just thought I'd throw out another option.

 

[Rock knocker]

The i-beams are "S" beams, I would have expected "W". I think they are posts for guard rails and are 5' long.

View attachment 319052

That sure looks like a W

 

[CNC Dan]

That sure looks like a W

looks W to me too. But I forgot to look it up before i left work. I'll have to see if i have a copy of the machinists handbook at home.

 

[Renze]

I would put a new wooden bridge in the same place as the old one, but add horizontal suspension cables so it doesnt float downstream in a flood. Much less complicated and pricey than vertical suspension. Especially when you dont have an anchor point nearby. KISS

 

[Renze]

A little larger than yours, but sometimes the experts don't get it right.

Same problem (yet smaller, not catastrophic) happened a couple of years ago here in Holland with the newly built Erasmus bridge.


Erasmusbrug - Wikipedia, the free encyclopedia

Shortly after the bridge opened to traffic in October 1996, it was discovered the bridge would swing under particularly strong wind conditions. To reduce the trembling, stronger shock dampers were installed.

If i remember correctly from the news back then, first the problem was patched by adding cross tie wires between the vertical pullcables. After analysis they came up with different shock dampers to change the natural frequency.

 

[crazyal]

That sure looks like a W

looks W to me too. But I forgot to look it up before i left work. I'll have to see if i have a copy of the machinists handbook at home.

I've never seen a W6x6 before I thought maybe an S. I was trying to get as many pictures as I could before the rain came so I never took a close look. After looking at the picture it's a W.

 

[crazyal]

That is awesome! Way overkill for my purposes, but really cool none-the-less. Wow, 1 1/4" cables is huge -- extremely difficult to work with. And I thought 1/2" cable over 70' distance was heavy. My wife (and I) wouldn't like the chain-link on the sides. It also looks like they double anchored the end deadmen. Thank you very much for the pictures! More ideas....

Marcus

Only on one end did they double up the anchor cables. I suspect they were worried about the ledge they were anchoring to. I think they took advantage of not having to do the engineering, if they did come from a ski area, since the ski area would know how much weight the cable could hold for a given span. I wouldn't want to handle the stuff but once it's up it would last a lifetime.