channels, angles or I beams for concrete block wall opening ? 1

[lubos1984]

Hello everyone and happy leap day!

I have some questions regarding a concrete block opening I'm currently designing. The opening is about 10' wide, 10' high and the concrete blocks are 10" thick. The existing concrete block wall is 25' from bottom to top. The wall is not a load bearing wall and not a shear wall. The wall was placed on top of a concrete footing. I am considering designing a steel beam to bear the 15' dead load above the opening with a 6" bearing on each side of the block wall

My question is regarding what would be the best type of steel beam considering shear, moment and deflection are satisfied. I'm deciding between I beam, channel and angles although not sure which one would work best. Should i consider lateral restraint of the beam by reinforcing the beam ends into the block wall, if at all possible.

As always thank you for your responses and happy to hear your thoughts!

 

[lubos1984]

I should also clarify that the wall is inside an industrial building and is just block wall without any veneer, etc

 

[JAE]

A single wide flange beam would work.
A pair of channels on each side of the wall - with a bottom plate across the head would work.
A pair of large (very large) angles back-to-back might work.
Just need to design them for strength and stiffness (L/600).

 

[skeletron]

Wide flange would be my selection for the first design iteration. Strength/deflection are well handled and good flange widths available (or potential to weld angles or bent plate to provide a wide enough bearing surface).

 

[hokie66]

I have seen double angles used, with the toes inserted into sawn out mortar joints before removal of the wall below.

 

[r13]

I prefer Hokie66's method, as the deflection of the remaining wall would be minimized by the angles throughout the construction, thus may lessen the problem of deep beam shears.

I suggest use truss analogy to get required tension steel; and, a slight camber of the angles would be helpful.

 

[jayrod12]

The angle method also allows for installing one side at a time, likely removing the requirement for temporary shoring of the wall. With a wide flange option, you need to temporarily shore the opening while you install.

But 10ft is a long span holding up 15ft of 10" block. might have a hard time getting angles to work in that scenario.

 

[hokie66]

I don't see a 10' span as a big problem with the double angles. You are only carrying the triangular area above.

 

[jayrod12]

Provided enough wall remains on either side of the opening to act like buttresses otherwise it supports the entire 15 feet the whole width.

 

[hokie66]

Yep, true, jayrod12. We don't know the full story. If it were one of my walls, it would be reinforced in both directions and fully grouted, so probably would span quite nicely on its own without a lintel.

 

[JAE]

I guess I thought this was for a NEW wall design... thus the back-to-back angle idea.

If it’s an existing wall then the sawcut, toe-in angle has sea per hokie66 would work.

 

[lubos1984]

Thank you for your suggestions! For the toe angle option I’d assume in that case contractor would as hokie indicated saw one side insert angle and repeat on other side and save the effort of temporary supportS. For bearing I was thinking 6” on each side. Would bonding of the blocks to angle be beneficial? Perhaps when angles are inserted, use grout or a bonding agent to fill in any gaps.