How to add more masonry (CHB) wall to clean wall

[stripez]

About 80 inches (2 meters) of 6" CHB (Concrete Hollow Blocks) need to be added to this parapet, but it has no rebars sticking out.

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This was previous picture showing the rebars sticking out but all already cut now.

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This was the previous picture of the owner showing when the flooring slab was placed (the column stirrups were not inserted).

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The distance between the 10mm rebars is 23.6 inches (600mm). Do you consider it very far? What distance of rebars and size do you use between rebars?

There were 4 hollow blocks layer put with the bottom pure concrete (originally to put waterproof membrane, the top layer of hollow blocks was put after the picture on record years ago).

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Ok, what is the best way to add another 80 inches (2 meters) of 6" CHB on top of it? Should I demolish half of it to access the existing rebars and weld new rebars to it? Or should I demolish all the hollow blocks to satisfy this?

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Or if you would just drill and insert epoxied rebars. How deep should they be placed and what size? Also the columns horizontal longitudinal support. But I'm afraid this would not be enough to develope the rebars length/overlap?

What would be the best way to do it? Thank you.

 

[phamENG]

You already have a thread going for this...

 

[stripez]

You already have a thread going for this...

I didn't include the images in that thread for the history of the existing hollow blocks. Also it's a complicated thread with many gigabytes of images that some may not be able to get load. This thread simplifies it.

There are many techniques for same situation. So I just need to get feedback from others on other methods to do it. For example. In some designs. There is a horizontal stiffener beam after the 2 meters height. Something you didn't detail. So I just need feedback from others if such horizontal stiffener is needed and what needs to be done. And other new techniques and methods.

 

[stripez]

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I plan to recommend chip hammering all 36 inches (almost 1 meter) of old parapet masonry to get to this base because I want to make it 3 meters high wall with another 1 meter above it as parapet above roof line (with an I-beam bracing the wall at 3m high). And want to start clean, so this thread stands alone. The above 2 photos may take time to load so imagine dozens of photos loading all at once.

I found old records of the owner. When you make walls. Do you start it flat from the beam itself or make a 4" support just like the above? I also found the old beam photo and dimensions. It is 12 inches thick beam, the masonry blocks (or CHB (Concrete Hollow Blocks) is 6 inches thin. Do you put your wall at edge eccentric to the beam or at center of beam?

I'll design it with other engineers carefully and we will get city hall to approve every details but I need to know some tips how to start at all. Most of them design it putting it at edge of beam. But it is the top storey so the wall can sway back and forth during seismic movement. How do you detail your wall base? The vertical supports is only 10mm (0.4") and distant 600mm (23.6") apart. If i'll drill and epoxy new bars. How big should it be and how deep is the drill. The Masonry (or CHB) will be 6 inches thick.

 

[stripez]

Let me detail what I meant by horizontal beam you didn't mention PhemENG but then I think others may not be doing it too. The old contractor habit is to put horizontal stiffiner beam at the 2 meter height (see green arrow) if the CHB (concrete hollow block) wall height is 3 meters even the horizontal spacing of wall is only 4 meters. This is ground floor with 3 meter height wall.

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Yet when wall height is 2.4 meters (which is for 2nd floor). No horizontal stiffener. I wonder if others add this horizontal beam too if the wall height is 3 meters.

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Why is the 2.4 meter a magic number? Because if it is a magic number. We may just make the wall height of 3rd and final floor just 2.4 meters, and remove all the thin metal roof and support (to make it lower by 600mm).