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Steel beam design where brick wall is removed.
6

Steel beam design where brick wall is removed.

Steel beam design where brick wall is removed.

(OP)
I am opening up an existing 8" brick exterior wall to 16'-6" for a room addition.  I need to keep the ceilings flush and the depth of the floor joists above is 9.25", so I am limited to about 9" for the new steel beam depth.  I am figuring the load on the beam to be to be 2220 pounds/foot.   The question is if I use A-50 steel instead of A-36 steel does the "E" number, 29,000,000 change between the 2 different grades of steel?  I am having problems with deflection--l/600 for masonry.   

RE: Steel beam design where brick wall is removed.

No. The E does not change for the grade of steel used. It looks like your stuck around L/420 huh? If you can use a 10" deep member you will definitely have no problem getting it to work.

Try designing your own beam made of plates maybe?

The masonry is existing right? Is your L/600 load include the brick? Where does the 2220#/ft come from?

RC
All that is necessary for the triumph of evil is that good men do nothing.
    Edmund Burke

 

RE: Steel beam design where brick wall is removed.

Tell the Architect that a soffit would really look nice at the lintel!

How about using an W8 with side plates? or a W8 with cover plates?

RE: Steel beam design where brick wall is removed.

(OP)
The loads come from, 300# from the floor above, 630# from the brick wall above the beam, 550 from a new flat roof, 540# from the pitched roof above the second floor, and 180# from the attic above the second floor.

I'm thinking I can change the direction of the new flat roof rafters and I can omit their load from the beam design.   If I do that I'll have a design value of I of 288 in4.  Additionally, if I install a 4x12x1/2" steel tube on the existing exterior of this 8" brick wall and a 4x8x1/2" steel tube on the interior of this brick wall with a 1/4"x12" steel plate shop welded to the bottom of the 4x8x1/2" tube, I can then field weld the 1/4" plate to the 4x12x1/2" steel tube.

I am thinking that this would make the installation of the beam relatively easy.  What do you think?   

RE: Steel beam design where brick wall is removed.

Two beams will have double the I of one beam.  Pair up the supporting beams and cut deflection in half.

RE: Steel beam design where brick wall is removed.

Not sure what of your load is DL and LL but, you only need to count LL for L/600 limits. In our office, we've also used a maximum limit of 0.3", but that is for longer spans. Maybe if you only counted your LL, a W8x67 (a column section) would work.

civilperson. He stated it was in place of an 8" wall. If you look at the W8 sections, you wouldn't be able to fit 2 beams into this area next to each other. What is the steel beam connecting too? Or is it just bearing in a pocket? You may be able to count on some stiffening from the connection and this may also reduce your deflection.

If you are a member of AISC you can search for papers about this topic.

 

RC
All that is necessary for the triumph of evil is that good men do nothing.
    Edmund Burke

 

RE: Steel beam design where brick wall is removed.

First I would try using a cover plate and see how close to L/600 or .3 I could get.

RE: Steel beam design where brick wall is removed.

I wouldn't count much on the connection. I keep your pin-pin design going. I tried checking a W8 with a C8 welded to both the top and bottom flanges since you have 9" of depth to work with. You could use the transformed section but the largest beam you could use is a W8x21 (bf=5.27") to fit into a C8x18.75 (T=6.13").

What if you installed a beam at a floor above to relieve some of the load on the lower floor?  

RE: Steel beam design where brick wall is removed.

The 0.3" deflection limit is from ACI 530 (masonry code). It will control for spans over 15'. This will be your limit, not L/600, so you actually need a higher moment of inertia than you originally thought.  

RE: Steel beam design where brick wall is removed.

Can you install 2 beams that are independent of one another. Make the stiif one carry all the exisitng brick and a second to handle the new load with your normal deflection criteria.

RE: Steel beam design where brick wall is removed.

What about adding an HSS section to either side of the web of the beam - like an HSS 6X3X1/4 - one that would fit between the flanges, and calculating the composite section I to reduce the deflection ratio?  Doesn't sound like you need much more at L/420 already.

Mike McCann
MMC Engineering

RE: Steel beam design where brick wall is removed.

2
Have you taken brick arching into account from the floors above? This may reduce your loads somewhat.

RE: Steel beam design where brick wall is removed.

You could have your beam cambered..

RE: Steel beam design where brick wall is removed.

"You could have your beam cambered.."

A cambered beam beam will deflect as much a a non cambered beam, just starting from a different point.  Also a cambered beam will initially only support the brick wall at the mid point.  I would not recommend it.  

RE: Steel beam design where brick wall is removed.

Any reason why the beam can not be upset so that it is above the second floor?  If it has 8" of brick above the entire length of beam you should be able to go above the floor depending on the low roof condition/detail.  Or you might want to consider adding a seperate beam to pick up the second floor load.
What keeps the water from running down the 8" brick exterior bearing wall and going into your new room?  Also, it will be difficult for the contractor to shore the wall to install the beam.  You might want to consider removing the entire brick wall and replacing with a stud bearing wall with brick veneer above the beam.

RE: Steel beam design where brick wall is removed.

how can the beam be upset if it doesnt have any feelings?

RE: Steel beam design where brick wall is removed.

"Not sure what of your load is DL and LL but, you only need to count LL for L/600 limits"

This not true.  You do not need to include any load applied to the beam before the brick is installed including the beam weight but any weight including the weight of the brick should be used towards the l/600 calculation.

RE: Steel beam design where brick wall is removed.

I agree with csd72.  The masonry will distribute loads to the supports of the beam.  Then, the load that the beam is carrying will be that applied within a triangle from support to support half the height of the beam span.

RE: Steel beam design where brick wall is removed.

(OP)
This opening is happening at a corner of the building. The extertior walls are 2 story, 8" brick walls with furring and plaster. Can I still do the arching effect of the masonry?   Or only consider arching on one side of the beam?  Thanks, your responses have been enlightening.

RE: Steel beam design where brick wall is removed.

You can probably do one sided arching if you've got some meat on that side of your opening.

I've used a slick detail using two channels.  Place on on either side of the brick above the opening, through bolt them together, and connect the bottom flanges with a steel plate (continuous or intermittent).  That way you don't use up any soffit depth.

Of course, the channels will be exposed to view so you'll need architectural approval for that.  You might also neeed to find a way to deal with water migrating in from outsite.  I think it looks cool.  I'm hardly impartial though...

RE: Steel beam design where brick wall is removed.

You can not have arching on one side of the beam.  Arching causes an equal lateral outward thrust on both sides over the opening.  You need masonry beyond the opening on both sides to resist it.  Also any windows could interfere with arching.  I would not depend on arching on such a large opening at the end of a wall.

I often use the double channel Adam suggested.  If you cut a horizontal groove into the the brick you can turn the channel leg in towards the wall into the cut and have the channel directly support the wall without need for shoring.

Make sure you alert the architect to the water problem as it will be a problem.    

RE: Steel beam design where brick wall is removed.

RCraine:
   The OP said the depth limit comes from ceiling depth, no width limit is required when the wall is removed below as long as there is support for the extra width at the ends.  Two W8 beams with a common plate across the top is what I envisioned for a shallow support with twice the moment of inertia of one W8.

RE: Steel beam design where brick wall is removed.

You are correct, civilperson.

This is why after I stated it wouldn't fit if pocketed, etc. I questioned how it was to be connected. I would imagine the width would be somewhat constrained by the width of the wall if the beams are spanning due to existing framing in the structure, just my guess though.

Hopefully BRENDANF has resolved his issues.

What did you end up doing BRENDANF?

RC
All that is necessary for the triumph of evil is that good men do nothing.
    Edmund Burke

 

RE: Steel beam design where brick wall is removed.

CSD:

We have "special" beams here...  They are able to take a lot of "stress", so they do have feelings.  Also, they do get tend to get torqued about a lot of the pressures they experience.  Nebvertheless, it's shear ecstasy for them.

Mike McCann
MMC Engineering

RE: Steel beam design where brick wall is removed.

(OP)
I took the new flat roof load and the floor load off the beam.

I planning using a W8x48 with at 1/2" steel plate welded to the bottom of the beam.

Thanks for your help!

RE: Steel beam design where brick wall is removed.

I am designing a lentil beam system to produce a 40 foot opening 8 feet high in an existing brick wall in an ancient retail store.  Will support the 40 foot hole with columns on 10 foot centers.

I plan to use double 8X6X1/2 angles with the 6 inch leg cut in the existing wall on either side and then through bolt the vertical legs on 2.5 foot centers.

Question - I see references to channels being used for this purpose but not many about angles.  Is there experience out there using angles??  Thanks

 

RE: Steel beam design where brick wall is removed.

mcaulfield,
have you thought of possibly, after the brick is removed from below, coming back and adding a plate across the seam of the angles so it will act as a single lintel.

Through bolting seems that it would damage the brick/block right above the lintel and that doesn't seem like a very good idea. Our typical details are for what I mentioned above. We've used it it many applications.

Hope that helps.
 

RC
All that is necessary for the triumph of evil is that good men do nothing.
    Edmund Burke

 

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