Shear Wall Maximum Length

[elinwood]

I'm a structural engineer by training working on the client's side - We are designing a 40 story structure with 32m x 25m footprint. The building's lateral load system will be a center core with perimeter columns. Our structural engineering consultant is saying:

"the structural opening is needed to keep shear wall length less than 8m. These openings can be door opening but should be 1.2m away from the corner"

I've never heard of this shear wall length criteria and couldn't find any reference for it. I've always thought that the less opening the better - so I asked him what he needs it for. He attached a page from ASCE 7 highlighting the 25% of the Load carried by Moment Frame requirement. Then he mentioned that it's "engineering practice", required to resist seismic load:

The link beam will enter plastic
Then the "wall leg"
Then the frame will provide resistance

Is this common practice ?

I understand if it's because of ductility requirement imposed by ASCE 7-10 as per Table 12.2-1 Section D.

Also, he mentioned that if the wall leg is too long, the rotation capacity is too small, and that in engineering practice the maximum shear wall length is typically 8m. Which rotation capacity is this ?

 

[KootK]

There's no code mandated maximum shear wall length that I'm aware of. It sounds as though your engineer is simply trying take steps to ensure a ductile, efficient structure in a seismic region. And, frankly, it sounds as though your structural engineer is pretty sharp.

The dual system shear wall / moment frame thing is a requirement for some buildings in some seismic zones on the U.S. It can be circumvented if one resorts to performance based design I believe.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.