Shear Wall placement -- reflectionally symmetric or rotationally symmetric?

Question

Is it better to add a shear wall that is reflectionally symmetric or rotationally symmetric?

I'm designing a confined masonry structure in a seismic zone. My understanding is that the shear walls are critical to protect the structure from failing during an earthquake.

Reflectionally symmetric shear walls	Rotationally symmetric shear walls

According to the Eurocode 8, confined masonry structures should locate shear walls symmetrically, but it doesn't state what kind of symmetry is best for structural integrity during an earthquake.

(3) The shear walls of the building should fulfil all of the following conditions:

a) the building should be stiffened by shear walls, arranged almost symmetrically in plan in two orthogonal directions;

Without specifying, I would assume by "symmetric" they mean reflectionally symmetric. However, the video guide to Confined Masonry produced by the Ecuadorian NGO EcoSur shows an example layout where the shear walls are located rotationally symmetric.

Is it better to locate the shear walls reflectionally symmetric or rotationally symmetric?

Answer 1

I would consider placing the shear walls in a way that provided an almost even strength against any earthquake direction.

This means The shear walls are radially almost evenly set around the center of the stiffness of the floor. In other words, the building floor plan is as strong in east-west and north-south directions as at 45 and 30 degrees.