Can someone confirm these #'s for a beam?

[FL Guy]

Just wanted to confirm these #'s I got online.
Im about to pull the trigger on a W8x18 beam.
Beam will be supported on both ends with 7" square tubing 1/4" walls.
Beam is 17' long.
The pictures show a 1000lb load, 2' wide sitting in the middle of the beam from 7'6"-9'6" (trolley width)

 

[bb29510]

not square tubing. HSS hollow structural steel, tubing

 

[gsmith22]

1.your beam shows negative moments at the hss column supports. there is no way you have end fixity between the beam and column to develop that moment and even if you did, you wouldn't want to design that beam that way. for max moment on beam, use PL/4 for a simply supported beam (so 2x what your printout shows). that moment is at the middle and your end moment would be 0.

2. in order to develop any bending moment without laterally torsionally buckling an I shaped member, you have to laterally brace/prevent twist of the beam at its ends as an absolute minimum. the more often you brace the beam in between its ends, the greater the beam's capacity. So confirm you have something keeping the beam from twisting/moving laterally (into/out of page) at each end - your unbraced length would then be 34'. this is typically like a lateral diagonal/kicker from the beam down to the ground unless this whole assembly is attached to something else.

3.your printout shows you have "continuous" bracing. I have never seen a beam supporting a trolly with continuous bracing - it is very unlikely your beam actually works becasue you have the wrong bracing specified. continouous bracing would be a concrete slab attached to the top flange of the beam between its supports. you should change that to an unbraced legnth of 34'. don't be surprised if your beam needs to be a lot bigger or with wider flanges.

4. if you have no lateral brace between end points, your unbraced length is 34' and not continuous. if you have brace points in between (you likely don't) then the unbraced length is distance between those points. the closer the brace points, the greater the capcity of your beam (relative to the developed moment from PL/4)

might want to get some engineering help with this. you are talking about moving big loads overhead

 

[WNYflyer]

-I would add that it looks like you have 2000# on the beam, 1k =1000# , 1.00k/ft x 2' = 2k = 2000#. Not sure if that was your intent.
-New wide flange steel WXxXX material would typically now be ASTM A992 with an FY=50ksi
-Assuming you are talking about some trolley riding on top of the bottom flange, if that is the case you need to aware of the local bending of the bottom flange at the trolley wheel locations. Given the loading probably not a big deal. Again if a moving trolley a minimum lateral loading should be applied and accounted for. Deflection criteria should probably be more stringent.
-As noted above the spacing of lateral bracing of the compression flange of a beam is incredibly important and from my experience the most missed/misunderstood design criteria by non professionals.

 

[FL Guy]

-I would add that it looks like you have 2000# on the beam, 1k =1000# , 1.00k/ft x 2' = 2k = 2000#. Not sure if that was your intent.
-New wide flange steel WXxXX material would typically now be ASTM A992 with an FY=50ksi
-Assuming you are talking about some trolley riding on top of the bottom flange, if that is the case you need to aware of the local bending of the bottom flange at the trolley wheel locations. Given the loading probably not a big deal. Again if a moving trolley a minimum lateral loading should be applied and accounted for. Deflection criteria should probably be more stringent.
-As noted above the spacing of lateral bracing of the compression flange of a beam is incredibly important and from my experience the most missed/misunderstood design criteria by non professionals.

The beam should only show having 1000lbs on it.
Yes, a trolley will be on the beam.
Pic is when garage was first built.
Other pic is how I intend to brace the column.

 

[gsmith22]

FL Guy - i replied to your PM but all will benefit from this:

not sure where i got the 34' from - sorry about that. so column supports are 17' apart making beam span 17' and only potential brace points at 17' too. if beam/column system is not connected to the structure, then you need to interally brace the beam/column structure for stability which is more complex than just the beam alone. you are effectively building a stationary gantry crane. look for pictures of that online and they all pretty much have diagonals that brace the top of the column to the ground. how you are doing the column bracing won't cut it - i'd argue it probably doesn't even properly brace the column (and definately not the beam) becasue you are creating a very large cantilever column above the diagonal attachment to the column. run the diagonal from ground (so you will need a seperate base plate anchored to slab) up to top of column. that will brace the column - see below for beam.

If you intend to sit the beam on top of the column (so only beam bottom flange connected to column top plate), the beam would be braced IF the web of the beam could span sideways
(like a cantielver off the bottom flange) preventing the top flange from moving sideways. most webs are thin; its questionable if this works. most people deal with this by including a fitted stiffener between the webs and flanges of the beam directly over the column connection. that creates a stable system bracing both the column top and the beam. miss any of those parts and I woudln't be able to tell you at what load the system collapses because there aren't direct bracing load paths. it could work/it likely won't but its anyone's guess.

If you do what i note above you will be in good shape. then design your beam for 17' span (simply supported no end moments) with only bracing points at the support points (ie columns)

 

[FL Guy]

FL Guy - i replied to your PM but all will benefit from this:

not sure where i got the 34' from - sorry about that. so column supports are 17' apart making beam span 17' and only potential brace points at 17' too. if beam/column system is not connected to the structure, then you need to interally brace the beam/column structure for stability which is more complex than just the beam alone. you are effectively building a stationary gantry crane. look for pictures of that online and they all pretty much have diagonals that brace the top of the column to the ground. how you are doing the column bracing won't cut it - i'd argue it probably doesn't even properly brace the column (and definately not the beam) becasue you are creating a very large cantilever column above the diagonal attachment to the column. run the diagonal from ground (so you will need a seperate base plate anchored to slab) up to top of column. that will brace the column - see below for beam.

If you intend to sit the beam on top of the column (so only beam bottom flange connected to column top plate), the beam would be braced IF the web of the beam could span sideways
(like a cantielver off the bottom flange) preventing the top flange from moving sideways. most webs are thin; its questionable if this works. most people deal with this by including a fitted stiffener between the webs and flanges of the beam directly over the column connection. that creates a stable system bracing both the column top and the beam. miss any of those parts and I woudln't be able to tell you at what load the system collapses because there aren't direct bracing load paths. it could work/it likely won't but its anyone's guess.

If you do what i note above you will be in good shape. then design your beam for 17' span (simply supported no end moments) with only bracing points at the support points (ie columns)

Thank you. I appreciate your input

 

[strutaeng]

Is that post baseplate bolted to the concrete floor? If so, I don't think you really need those angled braced down there.

But bracing the top of the column is needed. Something between the building framing (although those members are usually pretty small) and attached to the top of the column with a vertical slotted connection is something I've designed on this type of application inside existing buildings.

Ditto on the web stiffeners at the beam ends.

You may not need the braces at the top between the beam and the column. If you add them, you will most likely change the moment from what that analysis you posted on the first post. It may or may not matter. @bb29510 has the right idea about the beam end not really being moment connections. The braces at the top may actually make it closer to moment connection depending on how they are detailed and how stiff they are.

Lastly, on these kinds of designs I apply an impact factor of 2 to the load. I think you already did that if you applied a 1,000 lb line load over 2 feet.

I think you have a good idea, and kudos for running numbers.

 

[FL Guy]

Is that post baseplate bolted to the concrete floor? If so, I don't think you really need those angled braced down there.

But bracing the top of the column is needed. Something between the building framing (although those members are usually pretty small) and attached to the top of the column with a vertical slotted connection is something I've designed on this type of application inside existing buildings.

Ditto on the web stiffeners at the beam ends.

You may not need the braces at the top between the beam and the column. If you add them, you will most likely change the moment from what that analysis you posted on the first post. It may or may not matter. @bb29510 has the right idea about the beam end not really being moment connections. The braces at the top may actually make it closer to moment connection depending on how they are detailed and how stiff they are.

Lastly, on these kinds of designs I apply an impact factor of 2 to the load. I think you already did that if you applied a 1,000 lb line load over 2 feet.

I think you have a good idea, and kudos for running numbers.

The column against the wall is sitting on the concrete footer and it's about 16" thick X 12" wide. The other column is sitting on 6" of concrete.
Both baseplates are secured to the concrete with 5/8" threaded rod and is epoxied 6-7" deep.
Below is a pic of how I anticipate securing the column to the base plate to help with twisting and horizontal movement. I have another c channel that’ll go in the back on the opposite side.

I can’t really add bracing from the column to the building uprights. The uprights are 2.5” square 14ga steel. Not sure what it would do if I did go that route since they are so small.

Adding beam stiffeners seems easy enough. Google showed me some square stock and it was welded to the top and bottom flange as well as the web on both sides and both ends.

 

[strutaeng]

The column against the wall is sitting on the concrete footer and it's about 16" thick X 12" wide. The other column is sitting on 6" of concrete.
Both baseplates are secured to the concrete with 5/8" threaded rod and is epoxied 6-7" deep.
Below is a pic of how I anticipate securing the column to the base plate to help with twisting and horizontal movement. I have another c channel that’ll go in the back on the opposite side.

I can’t really add bracing from the column to the building uprights. The uprights are 2.5” square 14ga steel. Not sure what it would do if I did go that route since they are so small.

Adding beam stiffeners seems easy enough. Google showed me some square stock and it was welded to the top and bottom flange as well as the web on both sides and both ends.

That's plenty. Actually kinda overkill. I like it!

No need for that diagonal channel on the base.

Understood. Let me think about the top connection and see the photos on my office screen. The good news is that bracing forces are generally pretty modest, often 200-300 lbs.

Are you making the welds yourself? You have welder at your disposal and some decent skills I assume?

 

[FL Guy]

That's plenty. Actually kinda overkill. I like it!

No need for that diagonal channel on the base.

Understood. Let me think about the top connection and see the photos on my office screen. The good news is that bracing forces are generally pretty modest, often 200-300 lbs.

Are you making the welds yourself? You have welder at your disposal and some decent skills I assume?

So no bracing is required on the base to keep the column from moving?

Yes I have a welder and I’ll be doing it myself. I’m no professional, but I feel confident in my
Welds.