Cutting an opening in unreinforced CMU wall 2

[asixth]

Hi guys,

I have the situation that has come up where a client wants to provide a new 9'(2700) wide doorway through and un-reinforced block. My job is to strengthen this wall so a lintel can span across the opening.

My initial thoughts were to strengthen the opening with steel and then rely solely on the steel to span the opening.

Has anyone had problems cutting unreinforced masonry to provide a doorway and what is the best detail I can use for this application?

 

[asixth]

For those who are interested in how this job finished, they where able to install the channel lintel with chemical anchors at 8" (400) centers to hold up the wall. Despite half of the anchors not being installed. Photos attached.

 

[asixth]

In the meantime, they want to include some additional cores through at CMU wall adjacent to a doorway. Would there be any issues with coring through a bond beam like they have shown. All the cores will be made through 1 block and I am assuming that the lintel with have enough bearing to transfer the loads down the block wall. The yellow you see at the bottom left of the photo is the door frame.

Also if critical reinforcement is cut during coring (say a slab), how can it be reinstated or strengthened.

 

[rowingengineer]

Lets make it interesting and say you have cut PT reinforced a slab, and cut through a duct. Lets also male it easy and assume that supervision ensures that the tendons have been adequately grouted after the application of prestress.

When a tendon is cut, the free end will become de-tensioned but after a short transmission length the full tendon force will be effective. This distance is in the order of 600 to 800 mm. The tendon, needs to be treated in order to give full corrosion protection (as does conventional reinforcement).

Thus you would prop (possibly you would want use jacking props to get the slab unloaded a little) Apply some carbon strips to the slab at the points of concern. These strips need to be in the order of the hole width + 2* 800mm + the bond length. Bob’s your uncle, you now have a structural slab again.

I also noticed that your name of the photo was Townsville, if this is where the project is located this is the time of the year to do your inspection, (if you’re going to do one), as the weather will be beautiful and warm.


When in doubt, just take the next small step.

 

[asixth]

No it was in Brisbane, they just got uploaded with my holiday photos that I tagged as Townsville, but Townsville was awesome.