bdlc2k
Structural
- May 6, 2010
- 26
A question about concrete sway frame: (correct me where I’m wrong)
When designing the columns, ACI allows us to use 3 methods – (a) Nonlinear 2nd order analysis; (b) Elastic 2nd order analysis or (c) Moment magnification.
In strength design of the columns and beams for wind controlled building, if we use (b) Elastic 2nd order analysis, we’ll reduce Ig by Ie=0.7*Ig for columns and Ie=0.35*Ig for beams. This will give us our concrete design for strength. This can be done fairly easily using Ram or ETABS. (right??)
When it comes to wind drift of the building, are the same reduction factors of Ig used as well? I know we will use service level wind loading, but not sure about reduction of Ig.
I’ve seen some fellow engineers run two models; one for strength and another for drift/serviceability. Anyone have a good reference to read?
I'm familiar with the equations, just trying to get the general process in order.
Thanks
When designing the columns, ACI allows us to use 3 methods – (a) Nonlinear 2nd order analysis; (b) Elastic 2nd order analysis or (c) Moment magnification.
In strength design of the columns and beams for wind controlled building, if we use (b) Elastic 2nd order analysis, we’ll reduce Ig by Ie=0.7*Ig for columns and Ie=0.35*Ig for beams. This will give us our concrete design for strength. This can be done fairly easily using Ram or ETABS. (right??)
When it comes to wind drift of the building, are the same reduction factors of Ig used as well? I know we will use service level wind loading, but not sure about reduction of Ig.
I’ve seen some fellow engineers run two models; one for strength and another for drift/serviceability. Anyone have a good reference to read?
I'm familiar with the equations, just trying to get the general process in order.
Thanks
