Shear Walls with openings

[civeng80]

Im portalizing the panels in the sketch by site welding plates in the joints.

Any ideas on how to work out reinforcement so that the frame can be a shear wall resisting the horizontal load ?

 

[asixth]

I think the header panel could only be used to share the lateral load between the two vertical panels. I wouldn't be trying to couple the two panels.

 

[civeng80]

So should the panels be designed as 2 vertical cantilevers ?
or using strut and tie method?

What about the door on the right panel ?

 

[asixth]

I think two vertical cantilevers with a trimmer bar across the door head. But either method should yield very similar results.

 

[civeng80]

Thanks asixth.

The thing is that the welded plates for holding the top (lintel) panel do transfer forces and the moment arm can easily account for the moment transfer at the joint. So in reality I am indeed portalising the 3 panels whether I like it or not.

So why not take these plate forces in account ?

 

[TXStructural]

The plates/connections will act eccentrically to the wall. Also consider buckling of the connection under the compressive load. I will assume this wind, since using the detail for seismic seems absurd.

The connections will also try to restrain the shrinking panels, which will set them up to crack under those forces. This is a very common failure in precast/tilt construction. It is common to NOT rigidly connect tilt-up parts near edges because of this. Embeds should be located on the order of two panel thicknesses, or more, away from panel edges.

You might consider a connection that would allow shrinkage to occur, but restrain the panels against gross movement. This is less tricky when it involves two panels already supported for gravity loads, and is needed only to bind them together for shear or overturning.

From the Engineering Tilt-Up book from the Tilt-up Concrete Association: "The use of lintel panels should be avoided whenever possible. Their use leads to additional panel elements and challenging connection details that can be more easily designed and detailed as part of a larger continuous panel." Also: "Ideally, the roof/floor framing connection point should be several feet away from the panel joint so there is not a concentrated load near the edge of a panel. If this is not possible, then the connection can be centered on the joint, so that the reaction is distributed equally between the two panels. The use of pilasters under concentrated reactions is not common but can be used when needed to accommodate large reactions. Typically, integral column strips with added reinforcing are used."

 

[civeng80]

Thanks TXstructural

They are all very good points.

However I have no control on the header panel (client insists on this one).

The client also insists on the welded plate system (he is a welder !)

So design the shear panels to transfer the horizontal loads only (confirm that they are wind loads).

No portalizing because of the eccentricity.