Things to be checked, if we get a spigot connection for a column
When we have a spigot connection, at top of the column and a base plate connection at bottom of the column, first we must check the clearance provided for the movement of the column in the spigot to avoid any difficulties during erection.
If the clearance is not sufficient, we must address the issue to the client along with some proposals. In our condition the following Suggestions were provided.
We can postfix the Chemsets at any one side of the column ends
We can increase the clearance to enable sufficient erection clearance for the column.
In the below case, the design demands to pre-fix the chemset bolts and have provided only 50mm clearance for the spigot movement.
Refer below snaps from model & structural design.
In the above snap, the bottom of column has 10 thick base plate with Ø12 Chemset bolts and the top of the column is connected to the slab through the spigot which has 10 thick top plate with Ø12 chemset bolts as per the structural design requirement.
The structural engineer advised to pre-fix the chemset bolts.
So, we need to check for erection clearance to install the column.
The clearance between Soffit to the top of slab is 2940mm (Refer model snap). When we deduct the projection of the chemset at top 30mm (10mm top plate thick + 20mm projection) and at bottom 45mm (15mm grout + 10mm base plate thick + 20mm projection) from the slab to slab clearance (2940mm) we get 2865mm (2940-30-45=2865).
But the length of the column (when the spigot is fully inside the column and the top plate only projects out) is 2865 (column length) + 10 (Top plate of spigot) = 2875 mm which is 10mm more than that of the clearance between chemset projections.
So, considering this 10mm extra length and providing 15mm clearance at top and bottom, we have prepared a markup proposing 50mm (clearance as per design) + 40mm (10mm extra length of column + 15mm clearance on top & bottom) = 90mm spigot movement for easy erection and this proposal was sent to client.
Client had understood the issue and agreed our connection proposal with 90mm clearance.
Our analysis towards erection possibility along with client’s attention and understanding of the issue that we have addressed made the columns easy to erect.
