View attachment 2958
In this first column bar lapping was at some distance from main bar so it is fine or any problem with this lapping?
Dear Reddy,
This was one of the first issues we've discussed. From the posts it appeared that there was a general consensus that trying to implement the following three requirements of Column Bar splicing was sometimes impracticable:
a) max 50% bars to be spliced at a section,
b) splicing at in the middle half of the column height, as well as
c) trying to keep a clear distance between laps of 0.3 development length
Reference to international codes brought home the point that while all codes frown on more than 50% of bars being lapped at one location, they allow it after a punitive increase in the required development length. This is significant in situations where you are tying the column reinforcement cage at the ground level, complete with column rings and lifting this cage by means of mechanized methods such as a Crane. (This is not an uncommon practice for towers). In such cases, bars of unequal length become very difficult to maneuver and it may become imperative to have a system by which you may splice bars at one location without compromising on the structural integrity. Presently we do not have such an option available to us in IS 13920.
This could be reviewed in the next proposed revision of this code. We would welcome more discussion regarding this and would like to hear apprehensions of changing this clause 7.2.1 in IS 13920. There were issues raised about what does one do or those buildings where there is a future floor provision. Would the lapping of bars be all at the same location? It appears in such a case you would need to provide taller pedestals for the future columns, up to say about half the proposed floor height.
Attached lapping of bars is incorrect location and incorrect method as per national and International Standards and construction industry practices.
Regards
Harshal