Older Masonry Code Provisions
Older Masonry Code Provisions
(OP)
I am looking at an existing building designed/built circa 1976. It is a single story building with steel joist roof & metal deck. The perimeter walls are load bearing 6" light weight concrete block. There is no indication of reinforcing in the block on the architectural plans or the structural plans. There are no specification books available. There are no x-braces or other braces or moment frames indicated on the plans. The exterior walls are acting as shear walls.
During this time period, was there a minimum requirement for reinforcing a masonry wall?
During this time period, was there a minimum requirement for reinforcing a masonry wall?






RE: Older Masonry Code Provisions
RE: Older Masonry Code Provisions
RE: Older Masonry Code Provisions
Dik
RE: Older Masonry Code Provisions
When I started, the minimum reinforcing we used (for reinforced masonry only as that was all that was allowed in our area due to seismic requirements) was (1)#4 @48 vertiical, and horizontal K-web at 24 (every third course).
Depending on where you are, unreinforced could have been allowed.
Mike McCann
MMC Engineering
RE: Older Masonry Code Provisions
The first sentence under "Shear Walls" in the masonry code is:
A plain masonry shear wall shall be designed so that no part of the wall is in tension.
BA
RE: Older Masonry Code Provisions
I am looking at an unreinforced (in all likelihood) masonry shear wall that the owner wants to put windows in to make several shorter unreinforced masonry shear walls that do not work.
On to figure this little problem out.
RE: Older Masonry Code Provisions
BA
RE: Older Masonry Code Provisions
I've still got a copy of the Structural Design Manual, I think that's the title... really good book! I also have a copy of the wind loading booklet that I've scanned and turned into a *.pdf doc. It has some pressure distributions that aren't available elsewhere.
Dik
RE: Older Masonry Code Provisions
I don't think I have that. Maybe you should make it available to the forum. Maybe SlideRuleEra could incorporate it into his impressive library.
BA
RE: Older Masonry Code Provisions
In areas where seismic or hurricanes loads were not used unreinforced masonry walls were very common.
They produced design tables for unreinforced walls for various wind pressures that varied based on the axial dead load on the wall.
A 6" hollow block wall had a section modulus of 50 in3
and an area of 40.5 in2 per foot of wall.
The allowable tensile stress was 23 PSI for Type S mortar and 16 PSI for Type N mortar. If not otherwise specified Type N in what was used.
It is possible to put new re-bars in the existing walls if you need them for shear. There are design procedures for perforated shear walls for plywood shear walls. The same procedures could be applied to a masonry wall so it can be assumed to act as one large wall at a lower average shear capacity.
RE: Older Masonry Code Provisions
I will be oming up with a way to reinforce the wall.
I was mostly checking to see if there was a provision in "a code" that said that a minimum amount of reinforcing was required even though the plans had no indication that reinforcing was designed for this particular wall.
RE: Older Masonry Code Provisions
RE: Older Masonry Code Provisions
During the 1970's they published a document referred to as the "green book" the was titled something like "Tentative Specifications for Engineered Masonry Structures". It was used commonly by engineers because of the documentation and contributing authors (Jim Amrhein(sp?) and others in California and other areas. Much of it was used in the design of many successful loadbearing structures in southern California in the late 1960's and 1970's.
Sperling - If you are looking at a 1970's building it may have been designed by the standards in this document, although it may not have built according to the standard. That will take some "digging".
This document ended up being the major basis for the first ACI 530 when it finally got published initially.
Dick