STRUCTURAL ENGINEERING FORUM OF INDIA [SEFI]

HIMMATLAL · SEFI Member Joined: 20 Jun 2010 Posts: 4

can anyone explain me the use of the fixed but support in staadpro. what happens when i tick the required forces & moments.

sakumar79 · ... Joined: 18 Apr 2008 Posts: 691

The Fixed But support condition is used to allow the user to define which degrees of freedom of a node are free and which are fixed.

For example, Pinned support is equivalent to Fixed But MX MY MZ (no movement allowed, rotation allowed)

A roller support can be defined as Fixed But FX FZ MX MY MZ (only vertical movement is restrained. horizontal movement and rotation are allowed)

Similarly, in case you want to add a horizontal restraint which does not give vertical restraint, you can define FIXED BUT FY MX MY MZ

Arun

sknsrinivasan · ... Joined: 15 Apr 2013 Posts: 293

Dear Arun
In support specification in staad I want to give roller support In fixed but whether I have to select Fx,Fz,Mx,My and Mz or I have to select only Fy
Regards
N.srinivasan

es_jayakumar · Posted: Fri Oct 30, 2020 3:51 pm Post subject:

Suppose your roller support is operating in XY plane.
You want to permit it to :

(1) move in X direction,
(2) rotate in XY plain as a pin joint &
(3) have no freedom for either rotation or translation in other planes / directions.
In that case, release (mark tick in the box of) Fx & Mz only.

E S Jayakumar

sknsrinivasan · ... Joined: 15 Apr 2013 Posts: 293

Dear Jayakumar
Thank you very much for your reply
I am having another doubt for column we have to release Fy,Mx,My and Mz to assign roller support

N.srinivasan

sknsrinivasan · ... Joined: 15 Apr 2013 Posts: 293

Sorry consider Fx instead of Fy and Mz instead of Mx,My and Mz

es_jayakumar · Posted: Sat Oct 31, 2020 10:13 am Post subject:

Please indicate whatever freedom & restraints do you want to assign to the roller support ( I mean translation & rotation permitted and their directions).

E S Jayakumar

sknsrinivasan · ... Joined: 15 Apr 2013 Posts: 293

I want to assign vertical roller and horizontal roller support for vertical member( I don't have have any idea which one is correct) If we assign horizontally Or Vertically In Column ,Will the result change? You explain

es_jayakumar · Posted: Sat Oct 31, 2020 10:51 am Post subject:

If possible, post the detailed drawing of your structure.

sknsrinivasan · ... Joined: 15 Apr 2013 Posts: 293

Sorry I don't have any drawing substitute portal frame I want to assign roller support in column top and bottom I asked this for understanding purpose only