CMU Constructability Question

[Buildor27]

Hello, I am a Project Engineer managing a small amount of Masonry scope which is something I have never dealt with. Our sub let me know that the current plans have constructability concerns, as it wont be possible to place the masonry with the hooked downs as shown. Since I am not a structural engineer, does anyone have any ideas on how this design can be modified to make it constructible? The CMU blocks are 6" and we are in a seismic zone if this helps at all.

 

[dik]

What are your loads like? I assume that's a cantilever providing lateral support for the CMU below. I don't like anchorages near the bottom of a shelf angle... the pullout forces become high.

What is the problem? Is it the dowelling of the rebar to the slab or the attachment of the shelf angle to the CMU upturn? It's an awkward detail, and not sure why it non-constructable (not sure about seismic issues) as long as the cantilever can take the load.

can you use a right angle hook and place a top bar in the CMU upturn, by knocking out part of the web so the hook can be turned 90 deg.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[phamENG]

Have them look into the availability of H-blocks, double open end blocks, or speed blocks. It's a C90 compliant block with no webs on the ends. I believe it was created in high seismic areas where 8" o/c rebar was frequently required and splices were problematic. So with these, you can run the rebar continuous from footing to bond beam at the roof, and the mason can slip the blocks in between, mortar them in place, and then grout the wall solid. There are other variations on the idea for wider bar spacings, too.

 

[hokie66]

Agree with phamENG. There is no reason why those two courses cannot be constructed with the bars epoxied bottom and hooked top.

 

[dik]

...and use epoxy fasteners at the top angle moving closer to the top and not using expansion anchors in masonry.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[hokie66]

What is that top line, anyway? If that is another slab, and the builder want to infill the two courses of block, then the constructability of the detail becomes more problematic.

 

[dik]

Why the shelf angle?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Buildor27]

Thanks PhamENG, those are a perfect idea for this application, appreciate it!

 

[phamENG]

No problem. Glad it helped.