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Column lapping problem

 
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xetrapal
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Joined: 26 Jan 2003
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Location: Gandhidham - Kachchh

PostPosted: Fri Apr 06, 2007 5:29 am    Post subject: Column lapping problem Reply with quote

 
Dear Sefians,

I have a practical problem. Column dowels kept for lapping on first floor slab have been cut or stolen. Now I want to start construction of one more floor, for which structure is properly designed. What can be done, so that structure stability is not disturbed? Said building is situated in Zone V. Will Hilty rebars do? Is Confining reinforcement necessary? Kindly Advise.

Regards from Pratik Joshi

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pvyas
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PostPosted: Fri Apr 06, 2007 6:22 am    Post subject: Column lapping problem Reply with quote

Please go through the sp-34 based on is for detailing of rcc structure. In the same if the lap length is not good enough to transfer the stresses than you can use the mechanical anchorage system.

Regards,

Parth Vyas.
Tecnimont ICB PVT LTD.
MALAD(W) MUMBAI.

-----Original Message-----
Message From  xetrapal[AT]red... [mailto:xetrapal[AT]red...]
Sent: Friday, April 06, 2007 4:30 PM
To: Vyas Madhusudan Parth (Mumbai - Civil)
Subject: Column lapping problem

 
Dear Sefians,

I have a practical problem. Column dowels kept for lapping on first floor slab have been cut or stolen. Now I want to start construction of one more floor, for which structure is properly designed. What can be done, so that structure stability is not disturbed? Said building is situated in Zone V. Will Hilty rebars do? Is Confining reinforcement necessary? Kindly Advise.

Regards from Pratik Joshi

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vikram.jeet
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Joined: 26 Jan 2003
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PostPosted: Fri Apr 06, 2007 6:28 am    Post subject: Column lapping problem Reply with quote

Dear Pratik,

Try to expose the Beam/slab/column reinforcement available at top
around the column by breaking the concrete.Provide L- shaped
new vertical  bars of the column with leg aligned to exposed- beam -reinf
and resort to welding , as much as possible.
In design of upper floors it is always better to take this as hinge
joint for vertical loads analysis. The fixity ,whatever available,
as result of welding will take care of seismic condition.
Epoxy application between old and new conc will further
add to joint fixity.

with best wishes

vikramjeet

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BDSNL at ltecd.ltindia...
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PostPosted: Fri Apr 06, 2007 6:34 am    Post subject: Column lapping problem Reply with quote

Dear sir,

This mail address has been changed. The person to  whom you want to
ask,  has left the organisation.

So Please don't send any mail , from today onwards.

Regards,
Bhaskar Dadsena

Please go through the sp-34 based on is for detailing of rcc structure.
In the same if the lap length is not good enough to transfer the
stresses than you can use the mechanical anchorage system.

Regards,

Parth Vyas.
Tecnimont ICB PVT LTD.
MALAD(W) MUMBAI.

-----Original Message-----
Message From  xetrapal[AT]red... [mailto:xetrapal[AT]red...]
Sent: Friday, April 06, 2007 4:30 PM
To: Vyas Madhusudan Parth (Mumbai - Civil)
Subject: Column lapping problem

Dear Sefians,

I have a practical problem. Column dowels kept for lapping on first
floor slab have been cut or stolen. Now I want to start construction of
one more floor, for which structure is properly designed. What can be
done, so that structure stability is not disturbed? Said building is
situated in Zone V. Will Hilty rebars do? Is Confining reinforcement
necessary? Kindly Advise.

Regards from Pratik Joshi

Posted via Email
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BDSNL at ltecd.ltindia...
Guest





PostPosted: Fri Apr 06, 2007 6:35 am    Post subject: Column lapping problem Reply with quote

Don't send any mail from today onwards.

Regards

Dear Pratik,

Try to expose the Beam/slab/column reinforcement available at top
around the column by breaking the concrete.Provide L- shaped
new vertical  bars of the column with leg aligned to exposed- beam
-reinf
and resort to welding , as much as possible.
In design of upper floors it is always better to take this as hinge
joint for vertical loads analysis. The fixity ,whatever available,
as result of welding will take care of seismic condition.
Epoxy application between old and new conc will further
add to joint fixity.

with best wishes

vikramjeet

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ahujavipul
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Posts: 225

PostPosted: Fri Apr 06, 2007 2:04 pm    Post subject: Column lapping problem Reply with quote

Of course you could look into the possibility of providing specialized coupling devices. But remember that as per IS 13920, no lapping of bars is allowed within the "connection zone"---which extends one sixth of clear height of story above the column (and below beam bottom). This detailing will now be considered non-ductile. Therefore the existing building will need to comply with current IS 1893. If its not possible--then do a retrofit on the existing structure.

Vipul Ahuja

On Fri, 06 Apr 2007 P.Vyas[AT]tic... wrote :

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kamleshpatel
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Joined: 26 Jan 2003
Posts: 15
Location: Mumbai

PostPosted: Sat Apr 07, 2007 4:35 pm    Post subject: Column lapping problem Reply with quote

Dear Pratik Joshi, Yes, you can use Hilti Chemical anchors for the same. From:Kamleshpatel@myway.com--- On Fri 04/06, < P.Vyas@ticb.com  wrote:From: [mailto: P.Vyas@ticb.com]To: kamleshpatel@myway.comDate: Fri Apr 6 11:52:06 2007Subject: Column lapping problemPlease go through the sp-34 based on is for detailing of rcc structure. In the same if the lap length is not good enough to transfer the stresses than you can use the mechanical anchorage system.Regards,Parth Vyas.Tecnimont ICB PVT LTD.MALAD(W) MUMBAI.-----Original Message-----From: xetrapal@rediffmail.com [mailto:xetrapal@rediffmail.com]Sent: Friday, April 06, 2007 4:30 PMTo: Vyas Madhusudan Parth (Mumbai - Civil)Subject: Column lapping problem Dear Sefians,I have a practical problem. Column dowels kept for lapping on first floor slab have been cut or stolen. Now I want to start construction of one more floor, for which structure is properly designed. What can be done, so that structure
stability is not disturbed? Said building is situated in Zone V. Will Hilty rebars do? Is Confining reinforcement necessary? Kindly Advise.Regards from Pratik Joshi Structural Engineers Forum of India   Structural Engineers Forum of India

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akjhacpwd
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Joined: 26 Jan 2003
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PostPosted: Mon Apr 09, 2007 5:55 am    Post subject: Column lapping problem Reply with quote

Dear Sefians
In such situation , weld the bars of first floor columns to the remaining bars.
In capacity building design that the IS 139320 follows, plastic hinges are not supposed to form in columns . But because of the possibility of excessive inelastic rotation at the column ends , it is preferable to detail the as plastic hinges.
Now in the given situation , weld thr bars , provide proper confining steel to column bars. For furher safety and obviating unnecessary debate on ductility  in design of the building , take R = 3  . If you can ensure  strong column and weak beam concept you can take R=5 also.
Hilti rebaring is a good choice in general , but not suitable in this case.

AKJHA

ahujavipul[AT]red... wrote:
Of course you could look into the possibility of providing specialized coupling devices. But remember that as per IS 13920, no lapping of bars is allowed within the "connection zone"---which extends one sixth of clear height of story above the column (and below beam bottom). This detailing will now be considered non-ductile. Therefore the existing building will need to comply with current IS 1893. If its not possible--then do a retrofit on the existing structure.

Vipul Ahuja

On Fri, 06 Apr 2007 P.Vyas[AT]tic... wrote :

A K JHA
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C.P.W.D. Training Institute, Ghaziabad
09312836256, 0120-2710791( Office) , 0120- 2710920 (FAX)

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kiranpujari
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PostPosted: Mon Apr 09, 2007 7:40 am    Post subject: Column lapping problem Reply with quote

Dear Pratik Joshi,

For this problem you can use Fischer Chemical Anchors which is used for
taking out dowel bars. This one will be more suitable is you want to
transfer full loads say within 30 minutes.

Alternatively other construction chemical companies like Fosroc / Sika have
chemical anchors which will take few hours for setting.

Best wishes,

Kiran

On Fri Apr 6 19:34:54 2007, ahujavipul[AT]red... <
ahujavipul[AT]red...> wrote:

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