Wrong Column Rebars Splice Location
Wrong Column Rebars Splice Location
(OP)
I need urgent response on this, please help.
The 40-storey bldg that we designed is currently under construction and is now on the 14th flr. The problem is that the bldg constructor had a huge mistake on the placing of column rebars making the location of the rebar splice very near the column joint and some columns have 100% of the rebars spliced. we cannot adjust the rebars cause the lower flr has alrdy been poured w/ concrete.
we all know that this is very unacceptable because this could be a weak pt. when an earthquake strikes.
also the code requires that for a seismic zone 4 region (which where we are), the column splice zone should be located at the center-half of the column height, and the maximun no. of rebars to be spliced at one section is 30% (or 50%) of the total no. of bars.
we have trouble on addressing this issue. chipping the concrete would be time-consuming and by far the most unacceptable solution. we also consider using mechanical couplers but estimate shows that its very costly (and besides we dont know if this is acceptable with the code).
anyone knows some solution with these?
thanks in advance..
The 40-storey bldg that we designed is currently under construction and is now on the 14th flr. The problem is that the bldg constructor had a huge mistake on the placing of column rebars making the location of the rebar splice very near the column joint and some columns have 100% of the rebars spliced. we cannot adjust the rebars cause the lower flr has alrdy been poured w/ concrete.
we all know that this is very unacceptable because this could be a weak pt. when an earthquake strikes.
also the code requires that for a seismic zone 4 region (which where we are), the column splice zone should be located at the center-half of the column height, and the maximun no. of rebars to be spliced at one section is 30% (or 50%) of the total no. of bars.
we have trouble on addressing this issue. chipping the concrete would be time-consuming and by far the most unacceptable solution. we also consider using mechanical couplers but estimate shows that its very costly (and besides we dont know if this is acceptable with the code).
anyone knows some solution with these?
thanks in advance..






RE: Wrong Column Rebars Splice Location
RE: Wrong Column Rebars Splice Location
RE: Wrong Column Rebars Splice Location
"A mechanical or welded splice should develop at least 125% of the specified yield strength when located in the high tensile stress in the reinforcement. Such splice need not be staggered, although such staggering is encouraged where the area of reinforcement provided is less than twice that required by analysis."
RE: Wrong Column Rebars Splice Location
yes we could just say that its their prob, but that not how it goes around here. i thnk it should be a team effort to find a solution 4 this. thnks anyway.
RE: Wrong Column Rebars Splice Location
yes the columns are part of the lateral system, and mechanical couplers is what we had primarily in mind, but cost is expensive and we have to wait for weeks for its availabilty.
RE: Wrong Column Rebars Splice Location
RE: Wrong Column Rebars Splice Location
Additionally, if you choose to "help him out" and come up with a fix for him I am not sure why you are so considerate of the cost to the contractor (i.e. the cost of the mechanicial couplers).
This is his mistake, not yours..... dont take so much headache on as a result of his failure to properly follow teh contract documents.
RE: Wrong Column Rebars Splice Location
RE: Wrong Column Rebars Splice Location
I doubt for alignment reasons that retro-fitting couplers will really help, although they may help on paper with respect to complying with code.
Should the critical splice location be shown on the drawings? Were they? If not was the contractor required to check the code for splice locations? My point being that it is not always clear cut that the contractor is 100% wrong, if there is any doubt the Designer has responsibilities to the Owner to assist with rectification to ensure the buiding is delivered in time and on budget.
Is there a possibility by revisiting the calculations and adjusting factors such as as-cast concrete grade that the columns will satisfy requirements?
RE: Wrong Column Rebars Splice Location
Chipping out concrete may be more expensive, but could probably be completed in less time.
Mechanical couplers may be less expensive, but you said it would take weeks to get - thus delaying progress.
I would provide these two options to the contractor and let them select which option works best for them when considering both cost and time. As mentioned in previous posts it IS their mistake and responsibility to provide the fix even when the EOR assists in identifying the acceptable repair options.
RE: Wrong Column Rebars Splice Location
Dik
RE: Wrong Column Rebars Splice Location
Is it possible to drill and epoxy grout additional bars to compensate.
RE: Wrong Column Rebars Splice Location
Why not saw off the columns down to an elevation above the desired splice point, chip the concrete to expose bars for lapping, then build a new cage on up?
BTW, who reviewed the rebar shop drawings?
RE: Wrong Column Rebars Splice Location
Bob
RE: Wrong Column Rebars Splice Location
RE: Wrong Column Rebars Splice Location
"you can have it cheap, fast, and good quality...now, pick any two."
i suggest letting the contractor propose the fix. if you propose the fix and it fails, you'll be the one completely on the hook for his mistake. the contractor is going to say, "well they missed the mistake too, proposed the fix, okayed the fix, reevaluated the fix, and signed off on the fix. therefore the fix-failure is the responsibility of the engineer". i suggest you forget the "team player" attitude and buddy system when dealing with contractors.
RE: Wrong Column Rebars Splice Location
RE: Wrong Column Rebars Splice Location
RE: Wrong Column Rebars Splice Location
Soliciting remedies from the contractor keeps him involved with the solution - try this first. Then, offer several additional options, together with schedule and cost impact. When a consensus is achieved, present a united front to the suits and get the job done TOGETHER. In the end, everyone should be involved, as this is after all a profession, right?
These things happen continually in this field - how we manage them is how we will be remembered. This time you may be bailing the contractor out - next time he may be doing the same for you.
engphila
RE: Wrong Column Rebars Splice Location
Sad but true. 95% of the time it's a one way street.
RE: Wrong Column Rebars Splice Location
If the rebar was detailed in such a way that the splices are not in acceptable loactions, and the splice that has now been noticed is only near a plane where the splice would be in a non seismic frame, has the detailing or installation been off from the get go?
Concrete removal is not fun, but it is possible to do quickly and well. Please maintain a friendly relationship with all involved. That said, the pain and cost or forcing an alternate solution will likely cause more pain than fixing things now.
In a recent situation, we were told carbon fiber could only be used to wrap a round column for our application. We had square columns. To form, reinforce, and wrap the squares to round would have been far more work than to delay briefly and chip and correct.
It is also key to find out who is the player truly responsible for the issue and work with them (even if it requires bringing in their higher ups) to review the situation and consequences.
Often times, a general contractors take on the repair work may differ from a concrete specialty contractor which may again differ from a rebar sub or designer.
Bring everyone to the table, outline what you need and expect and look for mutually benificial solutions.
Best of luck.
Daniel Toon
RE: Wrong Column Rebars Splice Location
RE: Wrong Column Rebars Splice Location
RE: Wrong Column Rebars Splice Location