Structural engineers needed for a beam calculation.

[yooperdave]

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

Don't walk away from the aluminum beams - run like the wind away from the beams.

Some one is going to get hurt.

Free of Charge

Yooper Dave

 

[Woody65]

Don't walk away from the aluminum beams - run like the wind away from the beams.

Some one is going to get hurt.

Free of Charge

Yooper Dave

Thank you.

 

[searcyfarms]

it might be cheaper to put in a low water crossing and doing some excavating how deep is the creek? 25 feet is pretty short, i helped my neighbor put in a crossing on a creek that was about 20 foot across 8 foot deep, we excavated the banks down and make it very wide to make it work, have to usually do a little grading if we drive thru when wet or need to cross when its wet time of year, its not wet running creek yr round tho

 

[Streetcar]

Strength of beam is based on it's material properties which you have not given. After strength is given, rating for beam can be given

 

[fried1765]

Don't walk away from the aluminum beams - run like the wind away from the beams.

Some one is going to get hurt.

Free of Charge

Yooper Dave

I absolutely concur! (long ago civil engineer)

 

[KennyG]

As an engineer, I would be very hesitant to use an unknown aluminum I-Beam in this application. However, assuming the dimensions you have given are close to accurate, what you have are beams that conform to a standard 8 inch lightweight I-Beam in dimensions. For an I-Beam, the weight capacity is W=8fS/l where W is the weight capacity, f is the fiber stress (in psi), S is the section modulus (1.9 inch**3 for this beam) and l is the span in inches.

Let's say the beam was steel, with a 20,000 psi allowable fiber stress (typical for something like A36 steel) and the beam is 20 feet (240 inches) long. Then the allowable load is ((8 x 20,000 x 14.2)/240) =9467 lbs. Note that this is a distributed load, so for safety it should be reduced to 1/2, or a little over 4600 lbs. I have no idea what a reasonable allowable fiber stress is for aluminum but I would guess it's a good bit less than for steel. I couldn't immediately find values for aluminum to use for beam calculations but I would hesitate to put a ton of weight on these beams.

Bottom line is you are not going to get much capacity out of these beams. Note that all the above is simplified and assumes the beams are adequately braced to preclude buckling or other out of plane movement.

 

[s219]

I don't even need to run the math to know that an 8" aluminum i-beam isn't going to support much over a 25' span if it's a main beam.

 

[searcyfarms]

i will say this, 2 beams would not be advisable to haul much of anything across in my opinion regardless unless you had a very substantial platform - a friend and i rebuilt a country bridge that was abandonded and rotted through on a property we take care of, the one i referred to for the low water crossing - the other creek we rebuilt the bridge on, it is 14 feet span, 8 ft deep, it has 5 steel 10" ibeams sitting on a 1 foot ledge on concrete abutments. THey are at 2 ft spacing and we installed 5 inch thick creosote timbers across the ibeams.

I have no idea how much that would support but we drove my 10K lb skid steer on it and it didn't seem to even move entering/exiting/sitting in the middle - we also tied the timbers to the ibeams as well as then put driving treads on top of the timbers out of CCA

 

[mikester]

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

I will give you a hint - You need to calculate the deflection to determine the safe working load. You are asking an engineering question with implied liabilities so not many people are going to put their neck on the chopping block for you on an anonymous user group. Hire a professional please and let them do the calcs. Safety first. If you dont know the answer then you probably shouldnt be doing the work.

I suggested the trailer because someone has already done the engineering for you.

 

[ProjectKing]

I will give you a hint - You need to calculate the deflection to determine the safe working load. You are asking an engineering question with implied liabilities so not many people are going to put their neck on the chopping block for you on an anonymous user group. Hire a professional please and let them do the calcs. Safety first. If you dont know the answer then you probably shouldnt be doing the work.

I suggested the trailer because someone has already done the engineering for you.

Exactly! Excellent Post.