Structural engineers needed for a beam calculation.

[Woody65]

I am planning on building a small bridge over a creek. About a 25’ span. Someone near me has 2 aluminum I beams for sale that are 25’ long, 8” width, 4” flange, .25 web and .35 flange width. I have searched for tables and or calculators that would give me the max load for this size beam to no avail. I only need a ballpark number to see if it is worth looking into. The bridge is only for personal use within my property for loads up to a 10k excavator. I know there are some qualified people on this site that can put me in the right direction. Thanks.

 

[mikester]

The cheapest thing to do is buy an old flat bed tractor trailer, remove the bogies and landing gear, and use it for your bridge.

 

[boomer1025]

The cheapest thing to do is buy an old flat bed tractor trailer, remove the bogies and landing gear, and use it for your bridge.

:thumbsup:

 

[Deere Dude]

Not an engineer here, but I would expect that aluminum size would be good for walking or maybe a small garden tractor, but not 10k.

 

[Woody65]

The cheapest thing to do is buy an old flat bed tractor trailer, remove the bogies and landing gear, and use it for your bridge.

Been suggested before. No go. Have no way of getting it to the property, removing the axles or getting it near the creek it has to cross.

 

[Streetcar]

What is strength of beams. Sounds small for excavaror

 

[Woody65]

What is strength of beams. Sounds small for excavaror

That’s what I am asking

 

[yooperdave]

I am planning on building a small bridge over a creek. About a 25 span. Someone near me has 2 aluminum I beams for sale that are 25 long, 8 width, 4 flange, .25 web and .35 flange width. I have searched for tables and or calculators that would give me the max load for this size beam to no avail. I only need a ballpark number to see if it is worth looking into. The bridge is only for personal use within my property for loads up to a 10k excavator. I know there are some qualified people on this site that can put me in the right direction. Thanks.

You need to find out the grade of the aluminum. You also need to determine the spacing of bracing for the compression flange. Unbraced beams will buckle if not accounted for with the applicable strength reductions. Should also check for local web yielding under a point load if applicable. This is rare in steel, but more possible with aluminum.

Concur with prior posts - these beams would most likely work for a garden tractor but not much more. The proposed equipment would be expected to overload the beams to the point of collapse - even if the material was steel. I have a pair of W10x68 x 30' long beams (2,000# each) which has a better chance of success.

Good Luck

Yooper Dave (WI PE)

 

[shooterdon]

I doubt a licensed engineer will provide free advice. After all, that is how they earn their livelihood.

I am a mechanical engineer but let my license lapse decades ago. I could do the calculations but there is nothing but downside. I no longer have liability insurance and an error in calculations opens a professional engineer to a lawsuit.

Not what you want to hear...but reality.

A friend of mine who did free lance engineering on the side was sued when a wall collapsed. The contractor was finally found at fault but it was dicey for a while. My buddy never did another side job and focused on his corporate job.

 

[Woody65]

Not asking for anyone to tell me what will work, just the load bearing off the beam. Geez???