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StructuralEng
StructuralEng, Consultant
Category: Structural Engineering
Satisfied Customers: 6930
Experience:  Structural Engineer
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House built in 2006. Floor section of interest is the

Customer Question

House built in 2006. Floor section of interest is the kitchen/dining room/living room featuring a 23ft 7in wide by 30ft long. Approx half the width is ceramic the other is 3/4 hardwood. It is a remodel project where I want to replace existing ceramic tiles for stone tiles (6.25 lb/ft) and existing wood kitchen countertops to quartz (18lb/ft).
The main support is provided by a W12x30 steel I-beam width wise.
The existing wood engineered trussed are approx 15ft long 16" OC and I will be adding 2-2x10 joists in between those to effectively bring the joist span 8" oc. (To reduce deflection between joists, single plywood issue). Existing trusses sit on top of the I beam chord and added 2x10 will sit on bottom chord. Other side of trusses and joists are supported by the concrete walls.
With added weight, I need a solution to solve the L/720 deflection rating for the steel I beam wich is the weak part of the remodel. According to local engineer, live deflection is L/400 and dead is L/210 making the I beam deflection the problem I need to solve. I don't want to add a center post I want to beef up the W12x30 as necessary.
I have access from bottom of I beam and sides (limited space because of existing trusses).
How can I strengthen the I-beam ? Replacing it is impossible.
Submitted: 1 year ago.
Category: Structural Engineering
Customer: replied 1 year ago.
I beam is simply supported.
Customer: replied 1 year ago.
Plan added. Area of stone tiles is delimited in blue.
Expert:  StructuralEng replied 1 year ago.

Hello. How are you doing? I'll be happy to assist you.

Customer: replied 1 year ago.
Great! I hope my simple explanations are enough to get this project going.
Expert:  StructuralEng replied 1 year ago.

That's a very good description, thank you

Expert:  StructuralEng replied 1 year ago.

One thing seems to not make sense so I will ask for clarification.

Expert:  StructuralEng replied 1 year ago.

You said the live load deflection is L/400 and dead load deflection is L/210? That means the dead load is about twice that of the dead load, which I would be VERY surprised about.

Expert:  StructuralEng replied 1 year ago.

Is it the dead load deflection that is L/210 or te total load deflection?

Customer: replied 1 year ago.
I am sorry I stand corrected. L/210 is for total load deflection.
Expert:  StructuralEng replied 1 year ago.

Great. That makes more sense.

Expert:  StructuralEng replied 1 year ago.

That is a very big deficiency to make up in the deflection. The solution (both the engineering and the installation) are not simple, but it can definitely be done

Expert:  StructuralEng replied 1 year ago.

It will require temporarily shoring the floors so the load can be removed from the beam, then welding a prop leek sized WT shape to the bottom of your existing WF beam.

Expert:  StructuralEng replied 1 year ago.

I can do all of the engineering and sketches for you as an additional service. This will include the size of the WT, the grade of material, the welding requirements, a procedure, and any sketches needed to show the information

Customer: replied 1 year ago.
I also need to know if the new WT needs to be on posts or can hang from the existing WT once welded. Minimum length required or same length.How much is such a service ?
Expert:  StructuralEng replied 1 year ago.

I will provide that for you, too. I'm not allowed to discuss cost in the chat, so I wi submit the offer for you to consider. If you accept, I will get you all the information today.

Customer: replied 1 year ago.
Ok thank you
Expert:  StructuralEng replied 1 year ago.

I do want to let you know ahead of time that the WT will be large and significantly increase the overall depth of your beam. Trying to increase the moment of inertia by a factor of 3.5 requires a lot of depth

Customer: replied 1 year ago.
Can the depth be more than half the current W12x30 ? Anything over 6in depth would restrict headroom too much making this solution impossible. If it can be a solution having less than 6in more depth or OR adding a larger beam than the existing one OR welding channels inside top and bottom chord. Minimizing depth is crucial on this project.
Customer: replied 1 year ago.
Can I be assured that proposed service will satisfy at least one of those constraints ?
Expert:  StructuralEng replied 1 year ago.

I can minimize depth, but without running the numbers I can't say for sure how deep it will be. I can do everything I can to limit the depth to 6" (nominal). It may end up being a WT and plates on the top.

Expert:  StructuralEng replied 1 year ago.

Doing some very rough calculations, I feel confident that we can get this to work with a nominal 6" depth maximum. It may be something like 6.25" or 6.5" actual, but it will be close to the 6"

Customer: replied 1 year ago.
I will go to the house project make exact measurements of maximum possible depth and come back to go ahead.
Expert:  StructuralEng replied 1 year ago.

Perfect!

Expert:  StructuralEng replied 1 year ago.

Hello, do you still want the additional service on this? If you could rate my answer, I would appreciate it.

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