Gantry truss - Column Base plate connection - Pin or Fix ??
Gantry truss - Column Base plate connection - Pin or Fix ??
(OP)
Normally , I have pin connection for portal frame or similar structure. However, I check the gantry truss say 16-30m span with the column pinned base connection, a large deflection occur compared to fixed based.
It seem to me that I have to use column base fixed connection.
It seem to me that I have to use column base fixed connection.






RE: Gantry truss - Column Base plate connection - Pin or Fix ??
What is your question?
RE: Gantry truss - Column Base plate connection - Pin or Fix ??
RE: Gantry truss - Column Base plate connection - Pin or Fix ??
RE: Gantry truss - Column Base plate connection - Pin or Fix ??
Then go ahead for rigid fixed base connection design.
Is it ok ?
RE: Gantry truss - Column Base plate connection - Pin or Fix ??
RE: Gantry truss - Column Base plate connection - Pin or Fix ??
It's not a particularly high building, do you know why the lateral deflection is high?
Maybe the columns are just too small?
There is nothing inherent in trussed rafters which would cause excessive deflection.
RE: Gantry truss - Column Base plate connection - Pin or Fix ??
RE: Gantry truss - Column Base plate connection - Pin or Fix ??
RE: Gantry truss - Column Base plate connection - Pin or Fix ??
Can you post a copy of that paper or give the author and a ballpark date?
RE: Gantry truss - Column Base plate connection - Pin or Fix ??
The above post is based on guidence offered in The Steel Construction Institute (Berkshire U.K.)publication SCI P252 titled 'Design of Single-Span Steel Portal Frames to BS 5950-1:2000'
RE: Gantry truss - Column Base plate connection - Pin or Fix ??
Analyse whole structure as pinned based for strength.
Provide a separate load case with a 10k.ft moment applied at each column base. This will give you the amount that the deflection is reduced for each 10k.ft of base fixity.
Use superposition to calculate what the required base fixity moment is to keep deflections at an acceptable level.
Design base to act as fixed at the serviceability level.
RE: Gantry truss - Column Base plate connection - Pin or Fix ??
Reference to the 20% base stiffness for defections can be found in Advisory Desk notes AD90, AD97 & AD194.
These can be accessed by doing a search on;
http://www.steelbiz.org