In this first column bar lapping was at some distance from main bar so it is fine or any problem with this lapping?
Is it column lapping is correct? if not tell me what happened.
- Thread starter SRINIVASAREDDY
- Start date
In this first column bar lapping was at some distance from main bar so it is fine or any problem with this lapping?
I will say that it is incorrect.
have always quoted on this forum and elsewhere, that all such details cant be generalized in fact lots depends on the structural drawings and structural engineer design.
once again would reiterate that for all structural matters always refer to structural drawings and take advice from the structual engineer.
am attaching a general drawing at one of my sites for reference purpose only, pls ensure that you consult your designer before implementing anything.
most of the details are covered for knowledge of all but again its a general drawing, always be specific and refer to your structural engineer ask him for general drawing for your site, all designers issue the same at the start of the project.
HockeyPuck
Active Member
amd007 You raise a great point - Even though this installation doesn't necessarily look like we think it should look like, it doesn't make it wrong if the designer prescribed it.....
It is very rare, using US concrete codes & agency specifications, that some of the laps (or in this picture's case, the non-contact laps...) are appropriate, particularly with the size of the bars installed. I, like you, would definitely want to consult the design engineer on this one....
This is incorrect, because most of lapping bars length are variable and as per SP 34, All the lapped joints length shall be lapping till bend of the alternate rod, which is not shown in attached pictures. Technically this is totally wrongs.
Dnyan Deshmukh
Staff member
It look like lapping of column is short.
from the pic it indicate the lapping of column not done before casting of columns.
After casting of the column bars are simply lapped which got short lap length which made crank to go up.
The lapping of column reinforcement bars should never fall in column beam junction area.
remedy for current situation -
break the column concrete so that bar with sufficient lap length can be lapped with bars coming from column.
in most of the cases remedy suggested by structural consultant for laps where it falls in column beam junction area is to stitch weld the bars at 3 places 2 on one face at ends and 1 stitch on opposite face of lapped bars at center.
you should show the lapping of column bar gone in column beam junction to your structural consultant and take approval from them for the same.
from the pic it indicate the lapping of column not done before casting of columns.
After casting of the column bars are simply lapped which got short lap length which made crank to go up.
The lapping of column reinforcement bars should never fall in column beam junction area.
remedy for current situation -
break the column concrete so that bar with sufficient lap length can be lapped with bars coming from column.
in most of the cases remedy suggested by structural consultant for laps where it falls in column beam junction area is to stitch weld the bars at 3 places 2 on one face at ends and 1 stitch on opposite face of lapped bars at center.
you should show the lapping of column bar gone in column beam junction to your structural consultant and take approval from them for the same.
Sivasankar Reddy
Newbie
Sir,
1.Column lap was not provided properly as the lap rod to be placed up to joggles(crank).
2. Junction area lapping should not provide.
1.Column lap was not provided properly as the lap rod to be placed up to joggles(crank).
2. Junction area lapping should not provide.
civil kumar
Newbie
Lapping should always be " Ld+300 "
and must be staggered from adj. bar,
in pic. lap is in tension zone which is wrong it's should be in compression zone i.e. in centre,
remedy: use HILTI and increase lap-length for the short-rebars
and must be staggered from adj. bar,
in pic. lap is in tension zone which is wrong it's should be in compression zone i.e. in centre,
remedy: use HILTI and increase lap-length for the short-rebars
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
It is a Wrong method, end of rebar and lapped bar who made angle should be in front of; It should tie as like as it look homogeneous Bar
Dhaval Thanki
Senior Member
It is incorrect method. Lapping zone should be maintain as per IS : 13920 or SP-34. Generally this type of issue have been observed in High dia of rebar like 25 mm, 32 mm and where floor to floor height is 3m. beacasue lapping length is more in such cases. Please first prepare BBS for column. Also Kindly take advice from structural designer.
Same issue I obsevred at my site also. Generally contractor are preffered cutting lenght 4m & 6m .But If you preffer cutting length 4m & 6m for column then it can not be possible to maintain lapping zone.
Same issue I obsevred at my site also. Generally contractor are preffered cutting lenght 4m & 6m .But If you preffer cutting length 4m & 6m for column then it can not be possible to maintain lapping zone.
