Monday, October 17, 2011

RE: ST. Structure

You may be a bit challenged in reducing the lateral drift with a moment frame.  A vertical truss would probably provide a lot more stiffness.  The base plate connection should be straight forward.  Reference the AISC DG 1 Base Plate and Anchor Rod Design.  I would consider using chairs and tensioned anchor rods to minimize lateral drift. 

Regards, Harold Sprague

Subject: ST. Structure
Date: Mon, 17 Oct 2011 11:08:28 +0500

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