H Beam load calcs

[qmdv]

I have a shop that is pole construction. The poles and trusses are 12 feet apart. Pretty standard. I have several lengths of wide flange 8" H beam. I will weld two together to make 26 feet. I will then hang it from three trusses so I can use a beam trolley and chain hoist. I am trying to figure what the max weight it will carry.

First post. But I am a Ford Barner


Tim

 

[lakeroadster]

Sounds scary as hell. I'll bet your trusses aren't rated for that... and your welds aren't either.

 

[raferguson]

I am with lakeroadster. A bad plan. Trusses and welds both an issue. If you want a beam trolly, buy a H-beam for the trolly, long enough to meet your needs. You could then use the shorter pieces you have already to make a support structure, bolted to the floor. Splicing I-beams is a really bad idea, especially when the weld is in the middle of the span. How much weight do you really need to lift? An 8 inch H beam is pretty stout, I doubt if you need anything that heavy, unless you are working on heavy equipment.

 

[qmdv]

Sounds scary as hell. I'll bet your trusses aren't rated for that... and your welds aren't either.

You may win the bet on the trusses but not the welds. I certified steam pipe welder in 1967 so I am not too worried. 7018 rod will do just fine. We went extra on the trusses when we built the shop. What I need to do is find out what the beam will carry at this time. Oh and the flange width is 5 1/4 inches.

Tim

 

[qmdv]

Splicing I-beams is a really bad idea, especially when the weld is in the middle of the span. How much weight do you really need to lift? An 8 inch H beam is pretty stout,

You just do not but weld a beam. Did one many years ago and I cut a 30 degree angle in each piece and fit them that way. I would like to be able to lift 2000 pounds max. I have the 8" in stock from a gas station canopy we demoed a while back.

Tim

 

[AP514]

Go to the local University. Talk to engineering teacher maybe he will use it for one of the lessons.
If not they might point you to a student that will do it for you...

 

[lakeroadster]

You may win the bet on the trusses but not the welds. I certified steam pipe welder in 1967 so I am not too worried. 7018 rod will do just fine. We went extra on the trusses when we built the shop. What I need to do is find out what the beam will carry at this time. Oh and the flange width is 5 1/4 inches.

Tim

Steam pipe welder ASME Section 1? Your qualifications expire if you haven't welded within a 6 month period.

And without x-ray your welds derate the capacity of the beam.

Any idea what the beam is? 18 or 21 lbs/ft?
http://www.saginawpipe.com/steel_i_beams.htm

 

[Firebrick43]

Is it a wide flange beam (w beam) or an h beam?? They are different! What's they weight per foot? It could be any where from 10-60+ lbs per foot and the properties are drastically different. What's the trolley size/length?

Steam and structural are not the same. Structural splices typically need doubler plates, which will limit if not prevent a trolley from traveling, but it depends as very large bridge cranes typically have beams joined with bolts/doubler plates.

Hanging a load from trusses without the engineering is very bad. Build a gantry.

 

[lonestarky]

I agree with everyone above, just concerned for your safety. Beams are usually bolted, not welded. My guess is, the truss is the limiting factor here. Find the capacity of the trusses, subtract the full weight of the beam/3. And that's your load.

Sent from my Pixel XL using Tapatalk

 

[matt_i]

The trusses can't handle it.

If I spliced an I-type-beam I would fishplate both sides of the web and strongback the top flange with heavy angle iron. It will be hard enough to keep it aligned. If these terms don't make sense consult with a millwright or an ironworker.

 

[readhead]

Welding the beam isn't an issue. AWS has standard procedures and specs for that process. Splicing beams isn't very common because they are available in sixty foot lengths. The times we have spliced beams is usually in retrofit situations in existing buildings where long lengths aren't practical.

H beam is the common description for a W or wide flange beam. An HP beam is a heavy version of a H beam used for driven piles.

As John indicated it is an W8x18 or W8x21 either of which would span 12' and carry 2,000 pounds. However adding that much dead and dynamic load to the trusses would be asking for trouble unless they were specifically designed for it. I don't know what "going extra on the trusses" means exactly but I doubt that it covers this application.

 

[Lelandwelds]

Go to the local University. Talk to engineering teacher maybe he will use it for one of the lessons.
If not they might point you to a student that will do it for you...

The trusses can't handle it.

If I spliced an I-type-beam I would fishplate both sides of the web and strongback the top flange with heavy angle iron. It will be hard enough to keep it aligned. If these terms don't make sense consult with a millwright or an ironworker.

You can go to a college or union hall and read back issues of " Welding Design and Fabrication". The splices are cut at a 90° from the flange for an inch or two and then on an angle. The idea is to increase the length of weld and pick up some strength from angulation.

You arent limited to an 8 " beam. You can split it lengthwise into two tees. Weld it up into a 3' or 4' tall truss. Eight inch is a little small and I always used H beams for columns but you work with what you have.

Welding the beam isn't an issue.

As John indicated it is an W8x18 or W8x21 either of which would span 12' and carry 2,000 pounds. However adding that much dead and dynamic load to the trusses would be asking for trouble unless they were specifically designed for it. I don't know what "going extra on the trusses" means exactly but I doubt that it covers this application.

There are charts which show loads for each beam with a given deflection. Do you have wood trusses? They grow that **** on trees. Who knows how strong it is.

The building sees a bunch of transient loads which are hard to model. Just weld a column under each end and be done with it. Dont forget possible side loading and hydrogen embriddlement.

 

[theoldwizard1]

I have a shop that is pole construction. The poles and trusses are 12 feet apart. Pretty standard. I have several lengths of wide flange 8" H beam. I will weld two together to make 26 feet. I will then hang it from three trusses so I can use a beam trolley and chain hoist. I am trying to figure what the max weight it will carry.

First, I have never heard of an "H Beam". You likely have an "I beam" turned on its side. There is very little strength in an I beam turned on its side.

If these are typical "structural" I beams, they should never be welded ! It is not your "typical" mild steel. If you want to make a trolley, cut/grind the ends as square as possible, and then use a couple of plates on either side of the "web" (the thin inside of the "I") and drill and bolt them together.

Your limitation is not the the I beam, it will be the trusses yo want to hang it from. Trusses are NOT DESIGNED TO CARRY ADDITIONAL HEAVY LOADS ! THEY ARE DESIGNED TO CARRY THE WEIGHT OF THE ROOF AND ASSOCIATED SNOW LOAD.

 

[lakeroadster]

Trusses are NOT DESIGNED TO CARRY ADDITIONAL HEAVY LOADS ! THEY ARE DESIGNED TO CARRY THE WEIGHT OF THE ROOF AND ASSOCIATED SNOW LOAD.

And wind loads and environmental loads etc.

Often times they are also specified to carry other loads. The bottom chord is often specified to carry live and dead loads.

But unless you know what it was designed for you must never assume. Benny Hill has some advice in that regard....

 

[theoldwizard1]

And wind loads and environmental loads etc.

Often times they are also specified to carry other loads. The bottom chord is often specified to carry live and dead loads.

Yes, they CAN be designed that way. Not common.

 

[TheEquineFencer]

There's a guy GJ member in Raleigh, NC that has a spreadsheet for beam loads. If he chimes in great, if not I'm not going to drag him into this.

I had an "I" beam in my first shop, free span it was a 7 inch flange 14 inch web with a span of 37 feet, rated at the center it was 4000 pounds max load STRAIGHT Down without a side load. If I sideloaded it, it flexed. I had a 4K hoist/trolley on it and "tested" it with a 8K pound tractor to see if the hoist/beam would stay there. Most of the time the most it saw was 1-2K pounds.

BTW, where is the OP located?

 

[ssdave]

I edited this post to correct a moment equation problem:

The strength of the beam and allowable load is a simple math problem, but as pointed out by numerous others, the truss strength is not.

for a simple beam of 24 feet supported by 3 trusses 12 feet apart, the math goes like this:

Fb=mc/I

m=13/64 Pl for beam spanning 3 trusses, where l = 12 feet (144 inches) between trusses with load halfway between 2 trusses, which is the loading where the maximum moment will occur.

for 8x10 w beam (lightest 8" beam available), s = I/c = 7.8 in^3 All other 8" beams will carry more load.

for steel beam, allowable bending stress = 24 ksi

substituting values and solving for P:

Fb=mc/I

m=13/64 Pl for beam spanning 3 trusses, where l = 12 feet (144 inches) between trusses
for 8x10 w beam, s = I/c = 7.8 in^3

for steel beam, allowable bending stress = 24 ksi

substituting values and solving for P:

24000= 13/64 P 144/7.8
P=24000(7.8)/((13/64)144
P=6400 lbs



So, an 8" beam can support a maximum of 6400 pounds with no factor of safety other than using the allowable strength. Allowable strength is not the accepted method of calculating this anymore, but for illustration purposes, it is probably okay. If I was really designing this, I'd use a LRFD design process instead. This is not sound engineering advice, just a math problem, for our amusement.

I neglected the weight of the beam itself and the trolley/hoist.

The beam itself weighs 120 pounds between supports, so you will lose most of that from your safe lifting weight. The trolley and hoist probably weighs another 200

So, your allowable would be about 6000 pounds, if the trusses would support it. I'd guess that the trusses can support only a tiny fraction of that weight.

So, for most normal loads, the beam will not be the controlling factor. The trusses definitely will. Your welds may or may not affect the outcome, with care and a gusset plate, I think you could keep most of the beam strength. Would be hard to accurately predict, I'd reduce it by a factor of at least 50% to be safe.

So, in general, the advice I would give is:

Have the system strength calculated by someone in the know that actually looks at the trusses, the beam, and the whole support system. First step is get true load capacity of the bottom chord of the trusses. The beam will probably not be the limiting factor, and the weld may not be. Connections of the beam to the trusses will also have to be appropriately designed.

 

[ssdave]

Okay, I did the first calculations from memory, actually looked up the moment diagram for a single load, the equation I had the first time was for both spans loaded. The capacity of the beam is less for the single load, here are the calculations:

Fb=mc/I
m=13/64 Pl for beam spanning 3 trusses, where l = 12 feet (144 inches) between trusses
for 8x10 w beam, s = I/c = 7.8 in^3
for steel beam, allowable bending stress = 24 ksi
substituting values and solving for P:
24000= 13/64 P 144/7.8
P=24000(7.8)/((13/64)144
P=6400 lbs


So, the allowable load will be less; about 6000 pounds instead of 8000. I'll edit my post above to match. Note that I also didn't calculate the distributed weight of the beam itself correctly, just made a simplifying assumption that doesn't affect the outcome significantly.

 

[wssix99]

Welding the beam isn't an issue. AWS has standard procedures and specs for that process. Splicing beams isn't very common because they are available in sixty foot lengths. The times we have spliced beams is usually in retrofit situations in existing buildings where long lengths aren't practical.

Rare, indeed!

It would take a really really special welder to do the job for me to get under a contraption like this! The only place I recall actually seeing something like this is on a large steel ship. Even then - there is a reason why those things come with life jackets!

 

[matt_i]

First, I have never heard of an "H Beam". You likely have an "I beam" turned on its side. There is very little strength in an I beam turned on its side.

If these are typical "structural" I beams, they should never be welded ! It is not your "typical" mild steel. If you want to make a trolley, cut/grind the ends as square as possible, and then use a couple of plates on either side of the "web" (the thin inside of the "I") and drill and bolt them together.

This is weirdness. An I beam flipped on its side is sooo springy...the Iyy being so low would tell anyone its NOK. Not to mention the trolley doesn't fit that way....

Suggesting splicing the center web with bolted plates is ignorant of how the I-beam works...the max stress is carried in the flanges...

As far as never welding on an A36 hot rolled I-beam I will refer you to someone who did it and lived to tell about it

 

[lakeroadster]

As far as never welding on an A36 hot rolled I-beam I will refer you to someone who did it and lived to tell about it

Welding an attachment bracket to the end of a beam is in no way comparable to splicing beams mid span.

This thread and some of the comments within are simply dangerous.

Some things need to be engineered by professionals, and implemented by professionals. This thread covers three of those. Truss Analysis, Beam Analysis and AWS D1.1 Structural Welding.

To do otherwise is a fools errand.

 

[readhead]

There is nothing mysterious about welding beams together. I don't understand all the fear. But then I owned and ran a structural steel fab shop for almost twenty years and still do some small jobs. There are standard procedures for any connection. Structural steel is welded in AESS conditions all the time. A welder with D1.1 qualification should be able prep, perform and pass inspection for any of the procedures.

 

[Lelandwelds]

First, I have never heard of an "H Beam". You likely have an "I beam" turned on its side. There is very little strength in an I beam turned on its side.

If these are typical "structural" I beams, they should never be welded ! It is not your "typical" mild steel. If you want to make a trolley, cut/grind the ends as square as possible, and then use a couple of plates on either side of the "web" (the thin inside of the "I") and drill and bolt them together.

Your limitation is not the the I beam, it will be the trusses yo want to hang it from. Trusses are NOT DESIGNED TO CARRY ADDITIONAL HEAVY LOADS ! THEY ARE DESIGNED TO CARRY THE WEIGHT OF THE ROOF AND ASSOCIATED SNOW LOAD.

I ll try not to be harsh here. Google is your friend. There is some truth here.

I edited this post to correct a moment equation problem:

The strength of the beam and allowable load is a simple math problem, but as pointed out by numerous others, the truss strength is not.

for a simple beam of 24 feet supported by 3 trusses 12 feet apart, the math goes like this:

Fb=mc/I

m=13/64 Pl for beam spanning 3 trusses, where l = 12 feet (144 inches) between trusses with load halfway between 2 trusses, which is the loading where the maximum moment will occur.

for 8x10 w beam (lightest 8" beam available), s = I/c = 7.8 in^3 All other 8" beams will carry more load.

for steel beam, allowable bending stress = 24 ksi

substituting values and solving for P:

Fb=mc/I

m=13/64 Pl for beam spanning 3 trusses, where l = 12 feet (144 inches) between trusses
for 8x10 w beam, s = I/c = 7.8 in^3

for steel beam, allowable bending stress = 24 ksi

substituting values and solving for P:

24000= 13/64 P 144/7.8
P=24000(7.8)/((13/64)144
P=6400 lbs



So, an 8" beam can support a maximum of 6400 pounds with no factor of safety other than using the allowable strength. Allowable strength is not the accepted method of calculating this anymore, but for illustration purposes, it is probably okay. If I was really designing this, I'd use a LRFD design process instead. This is not sound engineering advice, just a math problem, for our amusement.

I neglected the weight of the beam itself and the trolley/hoist.

The beam itself weighs 120 pounds between supports, so you will lose most of that from your safe lifting weight. The trolley and hoist probably weighs another 200

So, your allowable would be about 6000 pounds, if the trusses would support it. I'd guess that the trusses can support only a tiny fraction of that weight.

So, for most normal loads, the beam will not be the controlling factor. The trusses definitely will. Your welds may or may not affect the outcome, with care and a gusset plate, I think you could keep most of the beam strength. Would be hard to accurately predict, I'd reduce it by a factor of at least 50% to be safe.

So, in general, the advice I would give is:

Have the system strength calculated by someone in the know that actually looks at the trusses, the beam, and the whole support system. First step is get true load capacity of the bottom chord of the trusses. The beam will probably not be the limiting factor, and the weld may not be. Connections of the beam to the trusses will also have to be appropriately designed.

Okay, I did the first calculations from memory, actually looked up the moment diagram for a single load, the equation I had the first time was for both spans loaded. The capacity of the beam is less for the single load, here are the calculations:

Fb=mc/I
m=13/64 Pl for beam spanning 3 trusses, where l = 12 feet (144 inches) between trusses
for 8x10 w beam, s = I/c = 7.8 in^3
for steel beam, allowable bending stress = 24 ksi
substituting values and solving for P:
24000= 13/64 P 144/7.8
P=24000(7.8)/((13/64)144
P=6400 lbs


So, the allowable load will be less; about 6000 pounds instead of 8000. I'll edit my post above to match. Note that I also didn't calculate the distributed weight of the beam itself correctly, just made a simplifying assumption that doesn't affect the outcome significantly.

My eyes glazed over but what he said.

The trusses can't handle it.

OK. Mild steel has no molybdenum, tungsten, chromium, vanadium or any good stuff except for a tiny bit of manganese and carbon. It , like angle iron or flat, is literally ******* designed to be welded on. Now, **** falling on your ******* head is bad. No jury will argue. There are charts with the hard math already worked out. Pick a 3:1 or 5:1 or 15:1 safety margin. The scary part is your existing trusses. Dont use them. Stick a big fat freaking column under each end or build an A frame on wheels and stick the stupid thing on RR rail. This stuff was worked out a century ago.

Anybody with your former cert can do this in his sleep. Avoid stupidity. Think multiples of the capacity of the weakest part of the assembly. Dont ever stand under a load. Expect gravity to work every time. It will.

 

[rockettgpw]

Oh goody another "the sky is falling" thread.
Listen to Leland and ssdave.
Splicing beams is no problem if done sensibly. My Bil's shop has a 12 x 4 x30 long beam spliced in middle of its length with trolley and mezzanine floor on top. Not scary at all.
Dads shop has a 8x3x 30 long I beam with mezzanine as well. its a little bouncy but survived lifting a 6 cylinder industrial diesel with just enough permanent deflection to make the trolley self centre.
Neither of these beams has mid length support, just the steel end posts.

 

[Ironcrow]

I have several lengths of wide flange 8" H beam. I will weld two together to make 26 feet. I will then hang it from three trusses so I can use a beam trolley and chain hoist.

I cut a 30 degree angle in each piece and fit them that way.

Right. Pick your longest piece and use it for the center. Angle cut and put an extension on each end. Proof test it to see what deflects it 1/2 inch or whatever. Use it at half that load. Consult beam table to see what deflection to expect.

Like everybody else, I'd be more concerned about the trusses. If the beam fails it will be because it is too noodly, it will roll, buckle, collapse below the limits predicted by beam tables because it doesn't stay straight and upright. The most important part of this project is the trusses and roll bracing.

 

[Firebrick43]

First, I have never heard of an "H Beam". You likely have an "I beam" turned on its side.

In structual beams they are not "I beams" but are refered to as W beams. These are typically thinner in cross section and the shear Web is deeper than than the flanges typically. Their strength is biased to handling loads in the vertical direction.

S beams are in similar dimensions to W beams but have tapered flanges.

H beams typically are more square in outside dimensions, ie the flanges are as wide as the shear Web is deep. The flanges have a constant cross section and are not tapered. You can find very heavy beams (relative to their depth) in h beams. They are used more as pilings, vertical post, and anywhere there might be greater twisting loads.

 

[ssdave]

Right. Pick your longest piece and use it for the center. Angle cut and put an extension on each end. Proof test it to see what deflects it 1/2 inch or whatever. Use it at half that load. Consult beam table to see what deflection to expect.

Like everybody else, I'd be more concerned about the trusses. If the beam fails it will be because it is too noodly, it will roll, buckle, collapse below the limits predicted by beam tables because it doesn't stay straight and upright. The most important part of this project is the trusses and roll bracing.

I"d splice it at or near the mid-point, where it can be supported by one of the trusses that are 12 ft o.c.

Your advice is good if the beam was going to be supported only at the ends.

It all depends on how it is supported. After the support is determined, splice it at a low shear and low moment point, by looking at the shear/moment diagram for that support and load combination.

Your point about rolling/buckling is well taken, that is why support connections are critical.

 

[d300]

It would be good to have the OP tell us more about his trusses/general building design but they are most likely not up to anything remotely close to what he has in mind.

 

[WNYflyer]

FWIW assuming,

-W8x18 (8" +- deep x 5 1/4" flange width)
-A36 steel (Fy= 36,000 psi)
-12' simple span for simplicity
-Allowable Fbx= is about 18,000 psi rather than 24,000 psi because of the unbraced length of the compression flange. Unbraced length and its effect on buckling strength of the beam is critical in determining the correct allowable strong axis Fbx stress.
-15% of lifted load as a nominal vertical impact
-10% of lifted load as a nominal lateral load
-100# trolley weight
-50# hoist weight
-the applied lifted load capacity ends up being approximately 3000#
-The peeling down of the bottom flange due to the wheel loads controls the design. Common controlling criteria for wide flanges due the flange width and thin flange thickness as opposed to "S" section members with narrow thick flanges.

A36 steel is so prevalent because it is easily welded

Splices can be Pre-qualified complete joint penetration (CJP) **** welds in accordance with AWS D1.1 which was already mentioned by others. Geometry of weld, including prep angles, bevels, lands, etc per the AWS D1.1 pre-qualified welds based also upon the welding process being used. Probably can find the weld diagrams on the web.

Connections to the wood trusses and the ability of the wood trusses to carry the load.........who knows..........

Gets you in the ballpark but as always best to have someone look at the whole system for a complete design.

 

[6768rogues]

Steel buildings are not typically designed for extra loads. I would be concerned about the weight of the beam, not to mention any load you attach to it.

 

[brownbagg]

just pull out your steel book and look it up

 

[lakeroadster]

just pull out your steel book and look it up

That's got wooden truss load data in it? Who knew?

 

[theoldwizard1]

Suggesting splicing the center web with bolted plates is ignorant of how the I-beam works...the max stress is carried in the flanges...

100% correct ! Of course you are assuming that the beam is only supported at the ends. From the description the OP stated, it will have multiple supports (from the bottom chord of each truss) every 16-24".

My best SWAG is, the trusses will fail long before the beam, welded or spliced.

 

[theoldwizard1]

In structual beams they are not "I beams" but are refered to as W beams. These are typically thinner in cross section and the shear Web is deeper than than the flanges typically. Their strength is biased to handling loads in the vertical direction.

S beams are in similar dimensions to W beams but have tapered flanges.

I have never heard them called anything but an "I beam" (not in the business). Learn something new every day ! From Wikipedia

An I-beam, also known as H-beam (for Universal Column, UC), W-beam (for "wide flange"), Universal Beam (UB), Rolled Steel Joist (RSJ), is a beam with an I or H-shaped cross-section. The horizontal elements of the "I" are known as flanges, while the vertical element is termed the "web". I-beams are usually made of structural steel and are used in construction and civil engineering.

 

[brownbagg]

to certifly a welder, they will weld a groove weld on a certain thickness of plate, then they will grind smooth, taking any reinforcement with it. Then i will bend the welded material 180 degrees on the weld, looking for any cracks or discrepancies. so yes a weld will hold structural without splice plates.

oh and i is a cwi for a living

 

[doge]

Learn how to use SAP2000 shouldn't be too difficult

Sent from my SAMSUNG-SM-G900A using Tapatalk

 

[Ironcrow]

I"d splice it at or near the mid-point, where it can be supported by one of the trusses that are 12 ft o.c.

Your advice is good if the beam was going to be supported only at the ends.

It all depends on how it is supported. After the support is determined, splice it at a low shear and low moment point, by looking at the shear/moment diagram for that support and load combination.

Your point about rolling/buckling is well taken, that is why support connections are critical.

Yes, implied in my comment, perhaps not clearly, is the idea that the trusses are inadequate and the beam will be supported at the ends.

The trusses could be reinforced for the purpose.

We entirely agree that this is a "problem to be solved" not a "dangerous impossibility".