Adding new floor

[hoshang]

Hi everybody
Please find the attached link:

https://www.screencast.com/t/SpwBGNOjwx7

The lines in black are existing ground floor stone masonry walls. The lines in red are proposed positions for hollow concrete block walls. As shown some proposed walls are not cited on existing walls. The foundation (footing and soil) condition can support another floor. My first thought is casting RC beams on existing RC slab in positions of existing walls (acting as girders of greater depth) and shallower beams on the red lines (supported by girders).
Another option would be using steel beams instead of concrete in the upper floor.
What would be suggestions if I used steel beams supported by steel columns in the lower floor.
If any other ideas are there, I appreciate highly.
What would be considerations to account for?

 

[dik]

I cannot open your file... can you use 8" or 16" 'U' blocks and fill them with grout, rather than casting reinforced concrete beams?

Dik

 

[hoshang]

I cannot open your file

I'm sorry. I edited OP. Please try opening it again.

 

[hoshang]

Have you tried opening the link in the original post again? It is here:

https://www.screencast.com/t/SpwBGNOjwx7

 

[hoshang]

Hi

It maybe not clear.
We have a building (a part of its plan is shown in the attached link and this part is 1 story high). The building is about 15 years old. It is a load bearing wall system consisting of stone masonry wall 40 cm wide (shown as black lines in the attached link) and RC slab. The foundation (footing and soil) can support another story. So the client wants to add another story consisting of load bearing walls made of hollow concrete blocks (gamma=1610 kg/m3) (shown as red lines in the attached link) supporting RC slab above it.
My first thought is casting RC beams on existing RC slab in positions of existing walls (acting as girders of greater depth) and shallower beams on the red lines (supported by girders).
Another option would be using steel beams instead of concrete in the upper story.
What would be your opinion on these ideas?
What would be your suggestions if I used steel beams supported by steel columns in the lower story to support the upper story.
If any other ideas are there, I appreciate highly.
What would be considerations to account for?
I hope it's clear now.

https://www.screencast.com/t/SpwBGNOjwx7

 

[BAretired]

It sounds like the client is making bad decisions. Why would you want to use heavy bearing walls on Gridlines B, C, D and 4?

What would be your opinion on these ideas?

A better idea is to use a network of steel beams at the high roof level supported by columns which bear on the slab directly over existing walls.

Where future walls occur over existing walls, it's okay to use masonry bearing walls. Elsewhere, it would be better to use light, non bearing partitions.

What would be your suggestions if I used steel beams supported by steel columns in the lower story to support the upper story.

I would try to avoid this or keep it to a minimum as it means creating new foundations for the columns and awkward installation for the beams under the existing slab.

BA

 

[hoshang]

Thanks BAretired

Why would you want to use heavy bearing walls on Gridlines B, C, D and 4?

The client wants to add a new floor. So the architect made design and appointed using heavy bearing walls on Grid lines B, C, D and 4.

A better idea is to use a network of steel beams at the high roof level supported by columns which bear on the slab directly over existing walls.

A network of steel beams at the high roof level supported by columns will support the new RC slab. My concern is about using things supporting new heavy bearing walls so that they are not supported directly by the existing RC slab.

 

[BAretired]

The client wants to add a new floor. So the architect made design and appointed using heavy bearing walls on Grid lines B, C, D and 4.

Masonry bearing walls could be used in the second story if they align with existing masonry walls below. In other locations, lighter materials would be better, perhaps metal stud partitions.

My concern is about using things supporting new heavy bearing walls so that they are not supported directly by the existing RC slab.

A valid concern. The existing slab was not designed to carry heavy walls, let alone bearing walls. It may not be adequate to carry floor load if it was designed for light roof load. It may be sloped for drainage, requiring topping to bring it to a uniform level.

There is insufficient information to make any firm recommendations at this time. It is probably best to make the new roof as light as possible. Trusses or open web steel joists spanning from Gridline A to E would be a good way to avoid having interior bearing walls.

Good luck with the architect!



BA

 

[hoshang]

Thanks BAretired

Masonry bearing walls could be used in the second story if they align with existing masonry walls below

So here comes my suggestion

casting RC beams on existing RC slab in positions of existing walls (acting as girders of greater depth) and shallower beams on the red lines (supported by girders).

The bottom of shallower beams would be raised above the existing slab (a gap of say 5-10 cm between the new beam and existing slab). The top of it would be flush with the top of the new proposed girder.

 

[BAretired]

So here comes my suggestion

Quote (hoshang)
casting RC beams on existing RC slab in positions of existing walls (acting as girders of greater depth) and shallower beams on the red lines (supported by girders).

The bottom of shallower beams would be raised above the existing slab (a gap of say 5-10 cm between the new beam and existing slab). The top of it would be flush with the top of the new proposed girder.

You don't need RC beams in positions of existing walls. You have a bearing wall in those locations.

With shallow beams 5 to 10 cm clear of the existing slab, you would have to step over the beams at every door opening. It doesn't work.


BA

 

[hoshang]

You don't need RC beams in positions of existing walls. You have a bearing wall in those locations.

The beams in positions of existing walls would act as girders to support the new shallower beams (shallower beams would be in positions where walls don't exist)

 

[hoshang]

You don't need RC beams in positions of existing walls. You have a bearing wall in those locations.

The beams in positions of existing walls would act as girders to support the new shallower beams (shallower beams would be in positions where walls don't exist)

Trusses or open web steel joists spanning from Gridline A to E would be a good way to avoid having interior bearing walls.

That's a good choice.
May I discuss this choice?
My idea is installing steel columns in positions of existing walls using base plate and anchors with adhesives. Then placing steel beams between the columns with decking using shear studs and casting RC concrete so that the beam is acting as composite beam.
Note: Because of these difficulties the client is going to only use the specified plan in the attached link.

https://www.screencast.com/t/Nmgd7hwICkM

Then using light weight hollow concrete blocks (gamma=455kg/m3) for the partitions

 

[BAretired]

The new architectural Second Floor Plan changes my understanding considerably. Looks like Gridline B has moved closer to Gridline C. Wall B3-B4 appears to align with existing wall below, correct?

Wall D3-D4 and B4-D4 are going to be a problem to support. You will likely have to add two beams at second floor level and at least one column down to grade to support those walls.

Wall C1-C3 can't have a beam just above floor level because it has a double door. You may have to provide a beam and columns below the existing slab.

My idea is installing steel columns in positions of existing walls using base plate and anchors with adhesives. Then placing steel beams between the columns with decking using shear studs and casting RC concrete so that the beam is acting as composite beam.

I don't understand that at all. You don't need steel columns over existing walls. They are bearing walls in both first and second story. Maybe it would be best to draw some structural framing plans, one at second floor and one at roof level rather than try to explain it verbally. A picture is worth a thousand words.


BA

 

[hoshang]

Wall D3-D4 and B4-D4 are going to be a problem to support. You will likely have to add two beams at second floor level and at least one column down to grade to support those walls.

We can't add one column down to grade to support those walls at this location because the new column would be inside a study room in the ground floor.
I have another thought now:
Load bearing walls on grid lines A1-F1, A3-F3, A1-A3, F1-F3, B3-B4
Light weight hollow concrete blocks (gamma=455kg/m3) on grid lines C1-C3, C2-E2, E1-E2
Steel column on B3, B4, E3, E4
Steel beams on grid lines B4-F4, E3-E4, and any location required to reduce deflection of the RC slab of new roof.

A picture is worth a thousand words.

I'll upload a drawing as soon as possible.