calculation of masonry deflection??

[paullaup]

I have a reinforced masonry tower (10’-0” x 10-‘0”) within a building space (isolated from the building with expansion joints). How do I calculate the deflection of the tower due to seismic loads?? I want to ensure that when the tower deflects, that I have enough of an expansion joint between the tower and the main building around it.
I know that this may seem like a simple question to some, but masonry is probably my weakest area, and I want to be sure.
Any help is greatly appreciated.

 

[JAE]

You have to treat the masonry tower as a complete, separate structural entity and perform a seismic analysis on it. The deflection would be based on the E modulus for the masonry which should be available in your code. The moemnt of inertia is simply the cross sectional I of the tower, using the wall thickness appropriate for the masonry. If it is fully grouted concrete blocks, then use the full block thickness...otherwise, for partially grouted cells, you would use an equivalent wall thickness to calculate your I.

The building has its own deflection and this would be added to your tower deflection to determine a minimum gap between the two structures. This is because they will most certainly have different periods and sway in opposing directions at various times during the seismic event.