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xetrapal SEFI Member
Joined: 26 Jan 2003 Posts: 4 Location: Gandhidham - Kachchh
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Posted: Fri Apr 06, 2007 5:29 am Post subject: Column lapping problem |
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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 SEFI Member
Joined: 26 Jan 2003 Posts: 10
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Posted: Fri Apr 06, 2007 6:22 am Post subject: Column lapping problem |
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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 General Sponsor
Joined: 26 Jan 2003 Posts: 3839
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Posted: Fri Apr 06, 2007 6:28 am Post subject: Column lapping problem |
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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... Guest
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Posted: Fri Apr 06, 2007 6:34 am Post subject: Column lapping problem |
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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
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BDSNL at ltecd.ltindia... Guest
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Posted: Fri Apr 06, 2007 6:35 am Post subject: Column lapping problem |
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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 General Sponsor
Joined: 26 Jan 2003 Posts: 230
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Posted: Fri Apr 06, 2007 2:04 pm Post subject: Column lapping problem |
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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 SEFI Member
Joined: 26 Jan 2003 Posts: 15 Location: Mumbai
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Posted: Sat Apr 07, 2007 4:35 pm Post subject: Column lapping problem |
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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 Silver Sponsor
Joined: 26 Jan 2003 Posts: 147
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Posted: Mon Apr 09, 2007 5:55 am Post subject: Column lapping problem |
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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 :
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kiranpujari SEFI Member
Joined: 26 Jan 2003 Posts: 9
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Posted: Mon Apr 09, 2007 7:40 am Post subject: Column lapping problem |
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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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