CMU Horizontal Reinforcement Ties - Florida Building Code Section 2122 High-Velocity Hurricane Zones
CMU Horizontal Reinforcement Ties - Florida Building Code Section 2122 High-Velocity Hurricane Zones
(OP)
I am working on a project in a HVHZ in Florida for the first time. The structure is a reinforced concrete moment frame with reinforced CMU infill walls spanning vertically between beams. I am currently wading through the FBC trying to understand all of the requirements for reinforced masonry. I'm trying to meet the requirements of Section 2122 in order to avoid using tie beams and tie columns as required by Section 2121.
Section 2122.2.3 states:
Minimum No. 9 gauge ladder-type hot-dipped galvanized, stainless steel, or epoxy coating horizontal joint reinforcing at every alternate course [16-inch (406 mm) spacing], for reinforced masonry shall be provided. This reinforcement shall be tied to structural columns with approved methods. In addition, horizontal joint reinforcement shall comply with TMS 602/ACI530.1/ASCE 6 Sections 2.4C thru 2.4F and Section 3.4B.10.
What constitutes an approved method for tying horizontal ladder-type reinforcement to structural reinforced concrete columns? Also, what is the fundamental reason for tying horizontal reinforcement to columns?
Section 2122.2.3 states:
Minimum No. 9 gauge ladder-type hot-dipped galvanized, stainless steel, or epoxy coating horizontal joint reinforcing at every alternate course [16-inch (406 mm) spacing], for reinforced masonry shall be provided. This reinforcement shall be tied to structural columns with approved methods. In addition, horizontal joint reinforcement shall comply with TMS 602/ACI530.1/ASCE 6 Sections 2.4C thru 2.4F and Section 3.4B.10.
What constitutes an approved method for tying horizontal ladder-type reinforcement to structural reinforced concrete columns? Also, what is the fundamental reason for tying horizontal reinforcement to columns?






RE: CMU Horizontal Reinforcement Ties - Florida Building Code Section 2122 High-Velocity Hurricane Zones
As far as the why, if supporting the CMU infill top and bottom is good, then top, bottom and on each side is better.
But I'm confused, if you're trying to avoid the tie beams and columns, why follow 2122? Doesn't the code say something like that masonry designed by an engineer doesn't have to follow this section?
RE: CMU Horizontal Reinforcement Ties - Florida Building Code Section 2122 High-Velocity Hurricane Zones
From what I understand from researching past threads, Section 2121 with the tie beam/tie column requirements is a holdover from the predecessor South Florida Building Codes and Section 2122 was added to provide an alternative method exclusively using reinforced masonry without concrete tie beams and tie columns. As far as I can tell, I have to follow the requirements of one of these 2 sections for masonry design in a HVHZ.
RE: CMU Horizontal Reinforcement Ties - Florida Building Code Section 2122 High-Velocity Hurricane Zones
Mike McCann, PE, SE (WA)
RE: CMU Horizontal Reinforcement Ties - Florida Building Code Section 2122 High-Velocity Hurricane Zones
RE: CMU Horizontal Reinforcement Ties - Florida Building Code Section 2122 High-Velocity Hurricane Zones
As a practical matter, if you poured the concrete first, it would be very, very (two verys) difficult to install the CMU. The mortar joint against the concrete columns would be very iffy and there would be a lot of trimming of the block, not to mention the installation of the ladder reinforcing and the vertical reinforcing.
As far as this method of construction, you're probably right. I think it's a mix of prescriptive requirements and engineering. But I stopped fighting it a while back. It seems hell for stout and all the Florida contractors can do it and expect it.
RE: CMU Horizontal Reinforcement Ties - Florida Building Code Section 2122 High-Velocity Hurricane Zones
It would not be typical for the CMU infill to be placed first in non-load bearing construction as you would not be able to control your load path to the foundation. It is rare to see moment frame construction in HVHZ - most projects would go straight to shear walls.
RE: CMU Horizontal Reinforcement Ties - Florida Building Code Section 2122 High-Velocity Hurricane Zones
Although I'm doing the design work, another SE based in Florida is supervising the design and ultimately sealing the drawings. His recommendation was to provide dovetail slots in the columns and use a brick tie of sorts every other course along the height of the wall. I contacted Hohmann & Barnard about and they do not recommend his approach or have a product specifically designed for tying horizontal reinforcement into concrete columns, which is what lead me to pose the question here on the forum. Thanks again for your insight.
RE: CMU Horizontal Reinforcement Ties - Florida Building Code Section 2122 High-Velocity Hurricane Zones
The original design has massive 24" and 30" square columns and the general notes refer to the CMU walls as "filler walls", so I don't believe the CMU was counted on for load bearing. EZBuilding's point about the load path being uncontrolled is well taken. In my mind, isolating the filler walls from the frame for gravity loads is the conventional way to go, but I get the sense that things are done a bit differently in this hurricane prone area.
RE: CMU Horizontal Reinforcement Ties - Florida Building Code Section 2122 High-Velocity Hurricane Zones
RE: CMU Horizontal Reinforcement Ties - Florida Building Code Section 2122 High-Velocity Hurricane Zones
My preference is to detail it as non-participating, but that's where I run into the construction sequence questions. Plus, it is a departure from the original building design, which I am being encouraged to avoid. Are there any dovetail-type ties on the market designed for and approved for use as a horizontal reinforcement connector in a HVHZ? If not, I feel like I'm stuck with treating the CMU as a participating infill wall and employing the construction sequence Jed described.