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Posted on 2/13/20 at 8:35 am to wickowick
The bridge in that picture seems to be a max span of around 50 feet and that is being generous I believe. If you consider it to be 10 feet between the straight vertical members.
Weird design, I don't see a real bottom chord member, maybe they were trying to avoid high water creating horizontal loads on the bottom chord???
We have a conveyor housing at work that has a span of 100 feet. It has W8x40 top chord and bottom chord with W8x24's vertical every 10 foot and W8x24 lacing between the vertical members. It is about 10 foot high and 10 foot wide, it was designed for 75lbs/ft loading. +/-75,000 lbs. (Just and idea of sizes for that length)
Good luck NOCOLORS, sounds like a fun project but cheap is going to be tough, especially for a loaded tractor with a hopper full of lime.
Also an FYI, you generally don't want your splice in mid-span.
Weird design, I don't see a real bottom chord member, maybe they were trying to avoid high water creating horizontal loads on the bottom chord???
We have a conveyor housing at work that has a span of 100 feet. It has W8x40 top chord and bottom chord with W8x24's vertical every 10 foot and W8x24 lacing between the vertical members. It is about 10 foot high and 10 foot wide, it was designed for 75lbs/ft loading. +/-75,000 lbs. (Just and idea of sizes for that length)
Good luck NOCOLORS, sounds like a fun project but cheap is going to be tough, especially for a loaded tractor with a hopper full of lime.
Also an FYI, you generally don't want your splice in mid-span.
This post was edited on 2/13/20 at 8:40 am
Posted on 2/13/20 at 8:38 am to duckdude
quote:
We have a conveyor housing at work that has a span of 100 feet. It has W8x40 top chord and bottom chord with W8x24's vertical every 10 foot and W8x24 lacing between the vertical members. It is about 10 foot high and 10 foot wide, it was designed for 75lbs/ft loading. +/-75,000 lbs.
sounds to me like it was designed in India.
Posted on 2/13/20 at 8:40 am to civiltiger07
No in the USA but in the 70's
MK-Ferguson
Cleavand, Ohio
MK-Ferguson
Cleavand, Ohio
This post was edited on 2/13/20 at 8:43 am
Posted on 2/13/20 at 8:56 am to duckdude
Well I guess they like spending money on steel.
Posted on 2/13/20 at 9:01 am to No Colors
You’ll need a truss, if you choose the steel route. That would require someone to design it (assumes liability), material costs, fabrication, ship, and erect it. Footings or piles will need protection from scour, and possibly soils data for design. Seems like a lot of work compared to the railcar. Or if you diy this, do you value your life at 26k
Posted on 2/13/20 at 8:46 pm to The Implication
I would do what you have been doing the last three years.
Posted on 2/13/20 at 9:15 pm to Marlo Stanfield
quote:ive designed some bridges that span 160'...concrete girders.... But they were 82" in depth.
You shouldnt spam that far even if it was a solid beam. Asking for a disaster to happen.
ETA: 160 not 180
This post was edited on 2/14/20 at 1:35 pm
Posted on 2/13/20 at 9:24 pm to eng08
quote:there are some Bailey bridges that were set in WW2 that are still in use.
Bailey and acrow are like a million pieces - not a long term set it / forget it solution
Posted on 2/13/20 at 9:26 pm to Boudreaux35
quote:yes they make girders.
don't believe Boykin makes girders, at least not that long. They make precast concrete elements and piles, but I don't ever remember them making girders.
Posted on 2/14/20 at 4:22 am to No Colors
Not sure what cost difference would be, but might be worth looking at a laminated beam (Glulam) manufacturer
Posted on 2/14/20 at 5:46 am to Columbia
Not for a 75’ bridge
Posted on 2/14/20 at 5:58 am to civiltiger07
They can build them as big as you want and every bit as strong as steel beams. That’s a 100ft plus bridge thereThis post was edited on 2/14/20 at 6:07 am
Posted on 2/14/20 at 6:11 am to Columbia
quote:
They can build them as big as you want and every bit as strong as steel beams.
Sure with more vertical supports to reduce span than a bridge constructed with steel. However the op said he doesn’t want to use any supports to reduce the span. It is not feasible for the OP to build a bridge to span 75’ and carry 10 tons.
ETA: yea that is going to cheap to build.
This post was edited on 2/14/20 at 6:24 am
Posted on 2/14/20 at 6:13 am to No Colors
quote:
We have a low water crossing that worked well for years. But lately has begun to be a problem. A combination of high MS Rivers and silt, and a moving bank. Basically it's time for a bridge.
It may be easier and cheaper to get a dozer and work on the existing low water crossing. Bring in some rock and perhaps install a smaller bridge in that location. Not sure of your situation there but a thought
Posted on 2/14/20 at 6:34 am to No Colors
I could design you a bridge that would work and even do an FEA on it in a day... but you’re not going to like the amount of work it’ll require. 75’ is an impossible distance with no vertical support be it pilings or truss. Also, as BBVD said you most definitely do not want your connection in the center. You’d be much better off getting 3 33’ beams to make your span.
I’m no Civil Engineer but I am a Naval Architect that deals with steel structural strength every day
I’m no Civil Engineer but I am a Naval Architect that deals with steel structural strength every day
Posted on 2/14/20 at 7:22 am to reds on reds on reds
OP this is a walking bridge with a longer span but it should give you an idea of what's needed
Posted on 2/14/20 at 7:25 am to No Colors
I asked a similar question from an engineer a couple years back. Here is his reply.
These were my assumptions:
• 120ft span only supported only on the ends
• Using two beams (vehicle width apart) to make up the span
• Connection between the 2ea beams with some sort of decking to prevent lateral buckling of the span beams. As per CootKilla, 6400# worth of grating
• Beam material grade to be 50ksi
• 8000# load placed at center span (worst case scenario) and 6400# of grating evenly disctibuted.
• The span beams (at worst case scenario) would be utilizing 80% of their capacity, based up AISC code.
The two span beams would need to be similar to one of the of the following choices/examples:
(based on using 6400# of grating evenly distributed, and a 8000# vehicle load at mid span)
• W18x97
• W21x93
• W24x76 (most efficient choice via strength to weight ratio)
• W27x84
? If there is anything you can do to reduce the span or the load, that will reduce the required beam sizes.
These were my assumptions:
• 120ft span only supported only on the ends
• Using two beams (vehicle width apart) to make up the span
• Connection between the 2ea beams with some sort of decking to prevent lateral buckling of the span beams. As per CootKilla, 6400# worth of grating
• Beam material grade to be 50ksi
• 8000# load placed at center span (worst case scenario) and 6400# of grating evenly disctibuted.
• The span beams (at worst case scenario) would be utilizing 80% of their capacity, based up AISC code.
The two span beams would need to be similar to one of the of the following choices/examples:
(based on using 6400# of grating evenly distributed, and a 8000# vehicle load at mid span)
• W18x97
• W21x93
• W24x76 (most efficient choice via strength to weight ratio)
• W27x84
? If there is anything you can do to reduce the span or the load, that will reduce the required beam sizes.
Posted on 2/14/20 at 12:15 pm to CarRamrod
quote:
ive designed some bridges that span 180'...concrete girders.... But they were 82" in depth.
The longest span we have made to date is an LG-54 and it was 126’. 180’ is a loooong ways.
Posted on 2/14/20 at 12:36 pm to No Colors
The owner of a company I used to work for had some property that we were allowed to hunt on in the Alabama Blackbelt. It had several creeks that were on it and most crossings did not have any structure whatsoever. When the water was high you could not cross. One creek however they used wooden power poles and had all thread drilled through them to keep it together. Then had a steel cable around a large tree and through the bridge to keep it from washing away when the water got up. It was over 50' and I never drove my truck over it cause the road was too bad just getting to it. Several guys that hunted there crossed it many times.
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