Vertical Reinforcement CMU wall 2

[MMN54321]

I am try to figure out the code for vertical reinforcement in a cmu wall.
The Florida Residential Building Code Says to us TMS 402 and I don't see any other guidance in the code.
TMS 402 section 7.3.2.3.1 gives the min requirements,

So I would assume I would calculate what was needed and make sure it is above the minimum.

The maximum spacing is 120 in,

What is the code Workflow

 

[driftLimiter]

The vertical reinforcement will contribute to two primary load actions:
1) Out of plane bending due to wind or seismic.
2) In plane bending due to lateral loads.

Generally the process involves designing the wall as a slender wall per TMS 402 I will say for most typical residential walls this controls.
Then if you are using the masonry for shear resistance you check your bars.

Finally you check Minimum.

Dont forget that TMS has additional requirements for Special Reinforced Masonry Shear Walls (your bars will need to be much closer, and you will need horizontal bars as well).

If you were able to provide some sketches or some loading diagrams perhaps I could offer more specific advice.

Cheers

 

[MMN54321]

Ok

I bought NCMA Direct Design Software,
In its initial inputs I have to pic whether I will use Ordinary, Intermediate or Special.
Why pick on of these first?

 

[driftLimiter]

The reinforcement and detailing requirements for each would change significantly. But those categories are categories of shear walls for seismic applications. See ASCE7-16 Ch. 12

 

[MMN54321]

That's on of the things that's confusing.
ASCE 7-16 Chapter 11 section 11.1.2 Scope No. 1 say Detached one and two family dwellings that
are located where the mapped Ss is less than 0.4 (This would be most of Florida if not all) or where ............... are exempt

Or

I could go look up the Site Class in Table 20.3.1 probably assume Site Class D
Then go look up values on a website Ss and S1 ...................


But then don't I have to pick ordinary, intermediate or special to proceed?

 

[driftLimiter]

Probably you can pick ordinary wall, the program must have design for in-plane forces as well. Verify with ASCE7 for your site requirements if this is okay.

 

[MMN54321]

How do I verify other than the book on Table 20.3.1
Also I go to Hazards by Location they will tell you Ss and S1 per your given site class and address from the table above

It dose in plan and out of plan checks
It also writes out all the calculation so you can check what it is doing

Once I know I can use ordinary and have proof by the code to back myself up
It will be nice to use.

Only thing is in the field I don't see anyone put uprights at 120 inches on center that's another concern of mine.

 

[driftLimiter]

The table in ASCE7 is Table 12.2-1. It is by seismic design category. If your are in SDC A then I would just use ordinary wall. This table indicates permissible seismic systems by site class and by building height.

 

[MMN54321]

I going to start doing it
ASCE Site Class will Default to (D) ASCE 11.4.3
Almost anywhere I pick in Florida gives me a Seismic Design Category of A on the hazard by location or if you
know Ss or S1 you can use table 11.6-1 or 11.6-2.
Then you go to the TMS 402/602-16 Table CC-7.3.2-1 Column 1 Shear wall Designation
Follow that down to Ordinary Reinforced Masonry and across to the permitted column and you will see the
SDC allowed.

I Think that would be my response to anyone questioning the placement of the rebar.

What do you think

 

[driftLimiter]

I think 120 o.c. sounds really far apart. Did too check TMS code minimums? I don't have my code with me and I don't normally design anything other than special reinforced walls, but normally I don't see anything over 48oc verts.

Don't let the program drive this decision be sure you know the code requirements.

 

[MMN54321]

Exactly that's what I am researching

So what I have found so far is ...............

TMS 402 Ordinary Reinforced Masonry Shear walls- Design of ordinary reinforced masonry shear walls
shall comply with the requirements of Section 8.3 or Section 9.3 and shall comply with the requirements Section 7.3.2.3.1
Section 8.3 is for designing with ASD
Section 9.3 is for design with Strength Design

TMS 402 Section 7.3.2.3.1 is Minimum reinforcement requirement's
7.3.2.3.1 states the maximum spacing shall be 120 inches

That's the code unless I am missing something some where

The program requires you to pick up front whether you are going to use Ordinary or intermediate or special shear walls.

 

[dik]

The Masonry Society... ah ah

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

-Dik

 

[masonrygeek]

Maybe this article will help. It discusses the idea of partially reinforced walls and how you can reinforce at 120" o.c. in some cases. We see a lot of overdesign of masonry by reverting to a max of 48" o.c. when that is really meant for higher seismic zones. In residential structures you will have a lot of corners and windows which require vertical bars at those locations (Section 7.3.2.3.1), so you may only see spacing at 120" in just a couple of areas.

 

[MMN54321]

Yes, everything you said makes sense.
I am going to read the article today.