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Help with Structural Engineering for Addition

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UgbeUgbe

Structural
May 17, 2023
3
I need help and ADVICE with this structural drawings. Is it possible to have two 10” deep Beams on the First Floor Framing instead of the two 12” deep Beams on the Drawing? This will allow us have a Flush Ceiling with the Existing. Attached is an LINK to the Existing and Proposed Architectural and Structural Drawings. I couldn’t upload the pictures here.

 
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Can you show a single plan with the beams shown in 'red' or something of that ilk? If the beams are steel, it is likely possible by increasing the beam weight to accommodate added deflection. Pick a smaller one with a larger section modulus and a larger Ix value... should work (subject to vibration issues). Something similar with wood...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik
 
I just attached a single plan with red dotted line showing the two beams to this thread and I also added it to the album on the link that I shared. The shorter Beams is a PSL and the longer one is a Glulam.
 
 https://files.engineering.com/getfile.aspx?folder=3fe6c23f-6c57-408e-8258-9b754b2fc9c7&file=4CA318F9-0CAF-4C35-9C64-ABD3CC76F4D2.jpeg
If this is for a school project, you should match or exceed the Sx and Ix, using wider beams. If this is an actual structure to be built, discuss the options with your structural engineer.
 
You will need to go to a stronger grade of PSL and wider. Stability should not be an issue if wider and the strength increase is linear. Equivalent section modulus = New Grade Strength / Old Grade Strength * Old section modulus. For deflection moment of inertia = b * d^3 / 12 for new member should be greater than the old one. Going from a 12" to a 10" beam, the increased width will be in the order of (12/10)^3 = 1.7 times the old width.

The second beam span appears to be quite large, and there may be problems with a direct substitution, with vibration.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik
 
What crappy drawings! There is nothing here that requires advice from Eng-Tips. If you can read the dimensions, you should be able to calculate the shear, bending moment and deflection for each beam and decide whether or not they can be reduced in depth.

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Why isn’t this question about changing the beam sizes being addressed to the person who did the design and drawings?
 
I have told the designer to change the Beam depth to 10" and he said it can't be done. But am thinking there could be other options. That is why I brought it here for all to see and advise. Thanks!
 
First, some clarifiaction - is the "designer" a structural engineer who calculated the the required beam size, or a non-engineer who used a span table to pick the beam size?

Second, what is your role in this project?

 
UgbeUgbe said:
I have told the designer to change the Beam depth to 10" and he said it can't be done. But am thinking there could be other options. That is why I brought it here for all to see and advise. Thanks!

This type of question is not the purpose of Eng-Tips. If you need specific advice on this structure, retain an expert.
 
If you know the I you need, and the depth is fixed at 10", then change the section ...
the thickness,
the width of the cap flange,
the grade of steel ?
or reinforce the beam with straps.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.
 
I have told the designer to change the Beam depth to 10" and he said it can't be done.

Did you ask why it can't be done? If you approach the designer respectfully, and ask why a shallower beam won't work, most likely they will explain it to you. If you don't understand the explanation, we can probably help you with that.

If the designer won't give you an answer to why it won't work, after you've asked nicely, then answers to the questions I asked about the designer's qualifications and your role will help us guide you in what options you may have.
 
"The shorter Beams is a PSL and the longer one is a Glulam." ... yeah well that means about as much to me as most things (don't ?).

can you not increase the I of a "PSL" or "Glulam" beam by adding to the section ? Could you glue multiple webs together ??

Could you not add another beam ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.
 
can you not increase the I of a "PSL" or "Glulam" beam by adding to the section ?

Not really. Anyway, that would make it deeper, and apparently it's already deeper than the OP wants.

Could you glue multiple webs together ??

Generally no, not with any amount of certainty that it will perform as expected.

Could you not add another beam ?

Maybe. Maybe not. It depends on the space available, and how it can be and needs to be connected to the other members. We know none of this. I'm not going to even hint at what could be changed in someone else's design, especially when I know nothing about requirements or the constraints.
 
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