Monday, October 17, 2011

RE: ST. Structure



I would go with rigid beam-column approach to provide lateral resistance. As for the column anchorage for combined tension and shear loads, you can still use a pinned base as long as the following measures are provided and checked:


·         Use four bolts with plate washers welded to the column base plate to insure that all four bolts participate in transferring the shear load

·         Insure a ductile failure in the case of overload

·         Insure proper development for the four bolts per ACI 318


For a good reference on column anchorage, I would encourage you to consult AISC design guide series 7. If you or anyone else in your organization is its member, you can download it for free. Good luck.



Mansoor Khan


From: Salman Siddiqui []
Sent: Monday, October 17, 2011 2:08 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