Steel Lintel in Masonry Wall - Seismic Details (ACI 530)

[EngDYIGuy]

I'm interested in the ACI 530 code requirements for steel lintel anchors into masonry (CMU) walls.

ACI 530 Chapter 7 Seismic Design Requirements 7.3.2.8.1 states:
Horizontal reinforcement shall be provided at
the bottom and top of wall openings and shall extend at
least 24 in. (610 mm) but not less than 40 bar diameters
past the opening.

I have seen many details of masonry bond beam type Lintels with lintel reinforcement extending beyond each side of masonry opening 40 bar diameters or 24 inches, whichever is greater.

However, all the steel lintel details I've seen have a bearing plate, and two grouted in place anchors in the CMU cell that the steel lentil is perched on. Where are the requirements in ACI 530 for the design of steel lintels, considering special seismic detailing? I haven't seen anyone include the above reinforcement extending past the openings for steel lintels?

 

[KootK]

Interesting question. I don't know the answer but have two thoughts:

1) I bet, under seismic, most of these steel lintel openings crack to high heaven at the corners.

2) I suppose you could pseudo apply the provision by putting rebar above the opening and extending it appropriately. Not ideal but some containment.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[thaidavid40]

We do something like what KootK says: we put bars in a bond beam on top of the steel lintel, and extend the bars at least 24" into the wall on either side of the beam's bearing cells. We make certain that the vertical bars in the edge column, and at least one additional column of cells, intersects these horizontal bars.

Thaidavid

 

[Guastavino]

I also do what thaidavid said. Steel lintel with headed studs into a bondbeam above opening. The bond beam extends past each side of the opening. I reinforce the cell adjacent to the opening up to the bearing plate below, then reinforce the adjacent cell from top of wall to bottom of wall.

Might be overkill, but meets the intent I would say.

With that said, I never try to use a steel lintel unless I have to. I don't like mixing materials if I can avoid it plus helps avoid thermal bridging on exterior walls.

 

[EngDYIGuy]

Thanks for the responses guys.