![]() If you look at section 14 for structural notes, TEK Notes 14-6 (Bond patterns) and 14-7 (working stress?) will give you good information and explain how intermediate bond beams can make a stack bond panel act like structural element just as a running bond panel does normally. The TEK note are written by professional engineers that hold prominent positions on most national code and standards groups (ASTM, ACI, TMS, IBC, etc.). Click on that, then on a state (any state) and a producer (any producer)to gain access to the 140 TEK notes on many different subjects. Look at the uper right quadrant of the home page for the TEK notes. In addition to the ACI 530 and the commentaries, a very good source to explain how masonry works go to the Natioanl concrete Masonry Association (NCMA) site. ![]() If this is the case and you assume a control joint on each side of each block in stack bond, then wouldn't the same requirement hold true? RE: Stack Bond Masonry JAE (Structural) 7 Jan 09 13:28 If you count on the joint reinforcement to transfer the load then I would need to specify truss type joint reinforcement, right? Because the ladder type would be unstable for load normal to the wall.Īlso, I was under the impression that the vertical bars required on each side of a normal vertical control joint in cmu walls was required for the very reason I mentioned above. If this is the case, how does the lateral load get to the grouted, reinforced cells? It seems to me that you would have to have a vertical bar in each block. I can't justify in my head that if I have vertical bars at say, 48"o.c., that the lateral load on the un-reinforced portions of the wall will transfer to the reinforced cells across the continuous head joints.Įverything I read says that you should think of stack bond as 16" vertical pilasters with a vertical joint on each side of the blocks. I have some pretty high walls and I am concered about the behavior of the stack bond under wind load. The architect has specified stack bond for aesthetics. This evidence may also be considered to support the adoption of more stringent recommendations in current American design requirements.I am the structural engineer for the job and this is the first time that stack bond has come up on a job for me. This evidence supports changes to current Canadian design requirements to include stack pattern masonry beams with this unit configuration. Using a stretcher unit with approximately 50% of the web height removed to permit grout continuity demonstrated no significant difference between running bond and stack pattern unit coursing. Beam stiffness, crack patterns, deflection profiles, and ultimate strengths are presented and discussed. This paper presents the results of an experimental study on 12 concrete block masonry beams with depths of two, three, and four courses to study the structural effects of a unit bonding pattern. The lack of research in the area of the structural effects of a unit bonding pattern has led to inconsistent and sometimes very punitive requirements for loadbearing masonry design in North America. However, in some situations an architect opts for a stack pattern (or stack bond) unit coursing, not realizing that there are structural implications to this choice. Loadbearing concrete block masonry construction in North America is generally designed by engineers as a 50% running bond pattern.
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