If it is possible to widen the column spaces for, say, the bottom half or third, I would do that because a wider footprint would increase the stiffness of the overall structure, reducing the drift.
Braced structure, even though it involves more members and connections, would be a better option.Chairs at the base with tensioned bolts would allow the base to be modeled as a fixed base. However, the foundation would require a suitable design to match the assumption of a fixed base.
Rajendran
From: Salman Siddiqui <ssiddiqui@olayandescon.com>
To: seaint@seaint.org
Sent: Monday, October 17, 2011 1:08 AM
Subject: ST. Structure
To: seaint@seaint.org
Sent: Monday, October 17, 2011 1:08 AM
Subject: ST. Structure
I am designing a stairway structure whose top platform is at 11m from ground as shown (only top platform supporting structure is shown, there are also to mid platform), the case is that we have only 1 m space between the columns. For that I have two options, either to provide lateral force resistance through bracing action by providing series of diagonal members at approximately about 45 degree for its effectiveness or to get lateral stiffness through moment action of frame by simply proving beams and making moment connection at beam/column joint. I think due to so small space of 1 m between the columns, simply providing beam with moment connection can simply fabrication by eliminating so numbers of diagonal bracing members.Please give your thoughts and opinions. Also how to make base plate to columns connection to transfer high uplift in lateral loads
Thanks in advance.
Salman Siddiqui
Structural Engineer