Reinforced core fill masonry wall for multi-unit of low rise building

[Huong83]

I recently design a 5 storey building with 2 basement.
All levels was using Reinforced core fill masonry walls for load bearing wall.
As my design manager told me to treat these Reinforced core fill masonry walls as a non-flexural wall. This mean the load will go directly onto the slab and columns. The computer model analysis will give slab thickness more than as you treat these Reinforced core fill masonry walls as a flexural wall.

If you do as he wants, is it conservative ?

In term of lateral analysis, the columns was designed with using these Reinforced core fill masonry walls as a flexural wall in order to avoid a conservative column design.
You think it is normal way to design or conservative design ?

Thanks

 

[KootK]

So your design has proceeded as follows:

1) CMU walls have been utilized as building shear walls and:
2) CMU walls have been ignored for gravity support of the slabs?

I believe that this will be conservative with respect to the gravity design but unconservative with redpect to lateral design unless:

1) the walls are designed for realistic minimum and maximum axial loads in combination with lateral loads and;

2) the vertical rebar detailing in the walls is continuous from floor to floor such that the block walls are true cantilever walls rather than just "infill" walls. One can use infill walls as shear walls with appropriate design and detailing but it's not normally done in my area. Without the appropriate design and detailing, using infil walls as shear walls can be a seismic disaster. The columns tend to fail in shear.

Where is your project located?

What does the wall to column connection detail look like?

Can you post a sketch of your floor plan?








I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[Huong83]

Kootk,

The CMU walls are cored filled with reinforcement vertical and horizontal. The wall vertically span from floor to floor. Agree with you that the concrete floor will be conservative design if these masonry cored fill reinforced walls are treated as non-flexural walls.

The reinforced concrete column to support ground level (transfer floor) and basement levels. The upper levels above ground floor are only masonry walls (unreinforced and reinforced core filled). These RC columns were designed by considering all cored filled reinforced masonry as flexural walls (Otherwise, these RC columns will be very heavy steel reinforcement).

The project is in Australia, not very sensitive to earthquake but lateral analysis still considered.

 

[hokie66]

I am having trouble making sense of your system. Specifically, I don't see how the design of the walls above the transfer floor have such a great affect on the columns supporting the transfer floor. Perhaps a section through the building would help.