2 Story 6" Masonry Bearing Wall
2 Story 6" Masonry Bearing Wall
(OP)
Hey Everyone...just picking everyone's brains again...
I'm looking to construct a 2 story masonry bearing wall...Not 2 story unbraced, there is a floor diaphragm that will brace the wall at approximately the mid height.
R606.2.1 states that the minimum wall thickness for a dwelling greater than one story must be 8" min. If i grout the wall solid, reinforce, account for gravity and lateral forces, and i can get the wall to work through my design, is there any other reason that this would be frowned upon?
Thanks,
I'm looking to construct a 2 story masonry bearing wall...Not 2 story unbraced, there is a floor diaphragm that will brace the wall at approximately the mid height.
R606.2.1 states that the minimum wall thickness for a dwelling greater than one story must be 8" min. If i grout the wall solid, reinforce, account for gravity and lateral forces, and i can get the wall to work through my design, is there any other reason that this would be frowned upon?
Thanks,






RE: 2 Story 6" Masonry Bearing Wall
RE: 2 Story 6" Masonry Bearing Wall
So is it still not allowed? Anyone know why?
RE: 2 Story 6" Masonry Bearing Wall
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RE: 2 Story 6" Masonry Bearing Wall
Unfortunately in the U.S., the sacred 4" module of masonry is habitual because it is easy and the 8" is convenient.
8" and larger are good for taller walls. In some U.S. areas, the 8" or 12" is habitual, and many areas offer 10", 12", 14" and 16" for designers that also wear suspenders in addition to belts.
In some countries, 6" block is a standard wall thickness for loadbearing multi-story apartments up to 20+ stories. This has been done for about 40+ years using ACI 530 or the standard ACI 530 is based on. - Just takes some good engineering, details and familiarity with masonry design. The buildings are typically partially reinforced with different strength masonry units that changes every 4 or 5 stories with the upper floors only containing nominal reinforcement.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: 2 Story 6" Masonry Bearing Wall
Surely I must be misinterpreting what you wrote. You don't mean 6" block is the primary load-bearding component for such a structure, right? Do you mean that the 6" block transfers the load to other structural elements, i.e., slab-to-wall-to-beam, or something like that?
RE: 2 Story 6" Masonry Bearing Wall
Are these the buildings that we see on the news in a collapsed state?
6" CMU supporting 20 stories - really?
RE: 2 Story 6" Masonry Bearing Wall
Block were color coded for strength and sampled at the plant prior to delivery. Since the block control the f'm of the walls. The mortar was mixed on site for timing purposes and spot checked and grout was a uniform strength made at a batch plant on site. Generally, clean-out were eliminated and core spaces were randomly checked visually or by remote video cameras. Unacceptable cleanliness created more frequent inspections or even the use of actual clean-outs that were a major construction cost and time.
The important thing is that the developer/builder/contractors were dealing with units that were purchased by the public and could not afford a failure/bad name since on bad building could ruin a very large company.
There have been attempts to crudely copy the system is some other areas. The engineers that designed the various large projects in different countries I saw spent a lot of time in the U.S. and followed Jim Amhrein's history in SoCal in the 1970's and had design seminars held in Brazil before Jim's concepts showed up in ACI 530. The system was a streamlined version of the reinforce mufti-story SoCal hotels/motels.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: 2 Story 6" Masonry Bearing Wall
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RE: 2 Story 6" Masonry Bearing Wall
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: 2 Story 6" Masonry Bearing Wall
They were asking whether the IRC provision would apply if they engineered it themselves.
It was a code applicability question.
It had NOTHING to do with 6" block wall capacity. Go back and read the post.
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RE: 2 Story 6" Masonry Bearing Wall
Let me add my objection to your continually telling this story, for several years now. Whatever they do in Brazil, it is not going to convince most of us here that it is good practice.
Now who gave him the star? Ridiculous.
RE: 2 Story 6" Masonry Bearing Wall
RE: 2 Story 6" Masonry Bearing Wall
The locations which give me fits in the design (and are exacerbated with 6" block) are bearing stress at the edges of openings and bending stresses in taller walls due to wind. The flexure gets to be hard to make work where you have small piers between large windows or overhead doors or significant width. If you get in a pinch with 8" block you can offset the bars to squeeze a little more flexural strength without increasing the wall depth, but a 6" unit is pretty narrow for bars anywhere but in the center of the wall.
I think the new masonry code is a little more generous with the allowable flexural capacity of a given reinforced section, but I have not used it yet.