Abrupt change in stiffness
Abrupt change in stiffness
(OP)
Hello,
Working on a new two-storey steel frame college building where the architect allows no vertical braces. I tried moment frames as a lateral resisting system, but story drifts exceeded the allowed limits, then I used some of the CMU infill walls as shear wall in combination with some moment connections in the framing of the roof where needed, which made drifts acceptable. The problem is that some of the walls I used in level 2 are not continued down to level 1 and level 1 is stiffer that level 2. Should I be worried about this abrupt change in stiffness?
Thanks for the inputs.
Working on a new two-storey steel frame college building where the architect allows no vertical braces. I tried moment frames as a lateral resisting system, but story drifts exceeded the allowed limits, then I used some of the CMU infill walls as shear wall in combination with some moment connections in the framing of the roof where needed, which made drifts acceptable. The problem is that some of the walls I used in level 2 are not continued down to level 1 and level 1 is stiffer that level 2. Should I be worried about this abrupt change in stiffness?
Thanks for the inputs.






RE: Abrupt change in stiffness
RE: Abrupt change in stiffness
It is the National Building Code of Canada. The area is not a high seismic zone. The seismic hazad index, Ie.Fa.Sa(0.2), is 0.52.
RE: Abrupt change in stiffness
Because the infill-shear walls, shouldn't be the 2nd floor stiffer than the first foor, eventhough the steel elements are smaller? Since it is in low seismic zone, as long as all members in a joint can adequatelly carry their's share of loads, the walls are properly anchored to the beams, and all deflections are within allowable limits, I don't see much of problems. Do you have specific concern in mind?
RE: Abrupt change in stiffness
RE: Abrupt change in stiffness