Speaking in Code – Talkin’ Turkey about the 2013 Masonry Code

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Let’s give thanks for the latest juicy and delicious edition of the Building Code Requirements and Specification for Masonry Structures (ACI 530-13 and ACI 530.1) which is really two different sections that comprise the same code book. The Building Code Requirements for Masonry Structures (TMS 402-13/ACI 530-13) pages C-1 through C-264 make up the first two-thirds of the code book. Specifications for Masonry Structures (TMS 602-13/ACI 530.1-13) pages S-1 through S-85 make up the last one-third of the book. The building code section makes the specifications an integral part of the code, and therefore all 349 pages of the book (ACI 530-13 and ACI 530.1-13) comprise the complete Masonry Codeand you thought Thanksgiving dinner made you sleepy!

The new masonry code (ACI 530-13) brings with it a plateful of changes both technical and organizational. The old masonry code was eight chapters and one appendix while the new masonry code (ACI 530-13) has grown to 14 chapters arranged in 5 parts with 3 appendices. The chart below provides an easy review and understanding of the reorganization of the new masonry code (ACI 530-2013).

Click on the chart to enlarge.

Table

A Cornucopia of Key Masonry Code ChangesACI530113D

Beyond simply restructuring how the information contained within the Code is presented, there are also several important changes to the code itself contained in the latest update. Some of the most noteworthy include:

  • Mortar bed tolerances for first course off the foundation are increased from 3/4” to 1 ¼”.
  • Requirements to cover the top of masonry walls have been modified.
  • The code requires an expansion of mortar joint thickness between masonry units and flashing.
  • Weld splices now require the reinforcement to conform to either ASTM A706 or a chemical analysis and carbon equivalent of the reinforcement steel.
  • Masonry cement mortar is now permitted for fully grouted participating elements in Seismic Design Category D or higher.
  • Previous code requirements for joint reinforcement and seismic clips for anchored veneer in Seismic Design Categories E and F have been eliminated.
  • The SI conversion equations were reviewed extensively and guidance on conversion factors are now provided in that code section (Pages S-237 through S-249) of the Code.
  • A new unit strength table for masonry units (Table 2) has been published and the unit strength table is significantly revised. The most significant revision is the correlation for a 2000 psi CMU laid in a type M or S mortar produces an assembly compressive strength of 2000 psi.
  • The previous version of the specification (old ACI 530.1-11 code) would require a CMU with a strength of 2800 psi to produce an assembly strength of 2000 psi. The brick unit strength table (Table 1) is unchanged.
  • There are revisions of design requirements for partially grouted shear walls, with a new 0.75 reduction in shear strength for partially grouted shear walls.
  • Mechanical splices in flexural reinforcement in plastic hinge zones are now required to develop the specified tensile strength of the
    splices bar, instead of the previously mandated 125% of the specified yield strength of the bar.
  • Figures have been added to the specification section (ACI 530.1-13) illustrating joint reinforcement lap splices (Figure SC-13) as well
    as figures to help illustrate and define the d-distances in walls and columns (Figures SC-14 and SC-15).
  • Modulus of Rupture Values have been increased (ACI 530-13 and IBC Chapter 21).
  • A clarification has been made that denotes that while bond beams are usually horizontal, they may be sloped or stepped in certain cases, such as when they need to match an adjacent roof line.

Changes Stuffed into the ASTM Code

In addition to some of the obvious masonry code changes set forth in ACI 530-13, some major changes in ASTM C 90-16, Standard Specification for Loadbearing Concrete Masonry Units introduce other notable Code changes:

  • One of the major changes is a reduction in web thicknesses of 6” and 8” CMU from 1 inch to ¾ inch.
  • An even greater change in ASTM C 90-16 is that the average compressive strength of an individual masonry unit was increased by 100 psi (from the existing 1900 psi to the new 2000psi). While this 100 psi increase may not seem that significant, this increase allows the  compressive strength of the masonry system to be increased from 1500 psi to 2000 psi. This 33% increase in the compressive strength of  the masonry system provides increased flexibility in the configuration of CMU, which allows producers and designers new options for CMU that have increased energy efficiency, reduced material use and configurations that ease constructability.

TMS…A Pilgrimage to Replace ACI 

Finally, 2016 marks the last time that the masonry code will be sponsored by the American Concrete Institute (ACI). All future editions of the code will be sponsored by the Masonry Society (TMS) and will be published simply as TMS 402 and TMS 602, Building Code Requirements and Specification for Masonry Structures.

You have likely seen this “TMS 402” and “TMS 602” nomenclature on the masonry code for years without thinking too much about what it meant. In short, TMS 402 covers the design and construction of masonry structures, and it covers numerous subjects, including: contract documents, quality assurance, materials, analysis and design, strength and serviceability, loads, reinforcement, seismic design requirements, veneers, empirical design, strength design, and a host of other topics. TMS 602 focuses primarily to control materials and construction, and it covers minimum construction requirements for masonry in structures, such as the placing, bonding, and anchoring of masonry and the placement of mortar, grout, and reinforcement. These are supplemented by specific project requirements.

All These Code Changes Got You Feeling Queasy?dirty-dishes

Stuck at the kid’s table with code issues? F&R can help! We regularly provide Lunch & Learn seminars as well as more intensive workshops on various code issues that relate to YOUR business. We’ll get you up to speed on the latest code changes and developments that will put you ahead of the curve and feeling pleasantly stuffed instead of overloaded. As a matter of fact, rather than souring the mood at the Thanksgiving table this year with a toxic discussion of current events, why not get the family embroiled in an old fashioned barn-burner of a debate about masonry code? Nothing goes better with Aunt Edna’s Watergate Salad than a vigorous exchange on current code topics!

Take a seat at the adult table.  If you have any questions about the elements of the code discussed in this edition of Speaking in Code, or any other code-related question, please feel free to contact Alan Tuck, F&R’s Executive Director for Code Compliance and Training.