www.sefindia.org

STRUCTURAL ENGINEERING FORUM OF INDIA [SEFI]

 Forum SubscriptionsSubscriptions DigestDigest Preferences   FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups  RegisterRegister FAQSecurity Tips FAQDonate
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log in to websiteLog in to websiteLog in to websiteLog in to forum 
Warning: Make sure you scan the downloaded attachment with updated antivirus tools  before opening them. They may contain viruses.
Use online scanners
here and here to upload downloaded attachment to check for safety.

IS:1893-2016
Goto page Previous  1, 2, 3  Next
 
Post new topicReply to topic Thank Post    www.sefindia.org Forum Index -> SEFI General Discussion
View previous topic :: View next topic  
Author Message
VIJAY N RATHOD
SEFI Member
SEFI Member


Joined: 23 Sep 2013
Posts: 14

PostPosted: Sun Jul 16, 2017 3:03 pm    Post subject: Reply with quote

Dear Arunkumar,

Please clear my 2 doubt,  

(1)

I think load combination should be like this way ??

Shear walls need to take 100% of load ie, 100 kN instead of 80 kN.
Hence, the load combination factors for EQX need to be boosted by 25%.
1.5 DL + 1.5 ELX becomes 1.5 DL + 1.75 ELX
1.2 (DL + LL + ELX) becomes 1.2 (DL + LL) + 1.45 ELX

0.9 DL + 1.5 ELX becomes 0.9 DL + 1.75 ELX.

(2)


If the Dynamic Analysis carried out then you replace EQX with SpecX (DynX)??.


If yes then base Shear accumulated at the base. in my case i am having 5 basement.  So Design may be very heavy ??




thanks
vijay
Back to top
View user's profile Send private message
hemalmistry
...
...


Joined: 01 Jul 2009
Posts: 59

PostPosted: Mon Jul 17, 2017 2:00 am    Post subject: IS:1893-2016 Reply with quote

Dear arun,


Drift limit for RC flat slab building according to indian code is 0.1% (0.001). While that according to ACI318 is 0.5% (0.005). But, it should be noted that according to ASCE drift is inelastic drift, which is R/I times elastic drift. So, permissible drift according to ACI is more, as inelastic drift is also more. Plz not R as per ASCE is appx. 2R as per indian code.



Drift according to indian code is elastic drift and inelastic drift will be 2R/I. We are comparing elastic drift with permissible limit. So permissible drift is less. There is no additional FOS as per indian code. Actually, permissible drift is double that of ASCE, as inelastic drift as per indian code is 2R/I times and not R/I times elastic drift.


Also, as per ACI352.1R, Drift limit for RC slab-column connection is 0.5% and that for PT slab-column connection is 1.5% for gravity shear ratio (Vug/Fi*Vc) between 0.6 to 1, and higher drift is permitted (some equations given) if gravity shear ratio (Vug/Fi*Vc) is less than 0.6. Even if drift is more than drift limit (drift capacity of slab-column connection), punching shear reinforcement can be provided to prevent drift induced punching.


Indian code only require to modify the structural system to control the drift. While according to ACI, we can increase drift capacity of slab-column connection by controlling gravity shear ratio by increasing flat plate thickness or by providing column capital or by providing drop cap or by increasing concrete grade or by providing punching shear reinforcement.†



For indian code we can say that "We stop where other start".


Regards
Hemal Mistry
Surat

Posted via Email
Back to top
View user's profile Send private message
arunangshu
Progressive Member
Progressive Member


Joined: 18 Sep 2009
Posts: 40
Location: New Delhi

PostPosted: Mon Jul 17, 2017 7:27 am    Post subject: Reply with quote

Dear Vijay,

As per NBC 2016 (Part 6) cl no. 5.3.3.3, vertical earthquake effects must be considered such that design seismic force: E = Eh + Ev.<o></o>
Eh- horizontal component
Ev- vertical component


Considering R = 3 and zone III, the following can be applied:
Av=((2/3◊Z/2)∙(2.5))/((R/I) )=((2/3◊0.16/2)∙(2.5))/((3/1.2) )≈0.05


The above component you can include in your design load combinations with dead load, such that the load combinations will become:


0.9D+1.5E -> 0.85D+1.5E | 1.5D+1.5 -> 1.55D+1.5E .. and similar.


For details of this approach, you can refer ASCE-7 or UBC 97 or IBC (I don't remember latest edition of IBC).


So this simplifies your job as far as vertical component of seismic force is concerned.


Best regards
Arun
Back to top
View user's profile Send private message Visit poster's website
arunangshu
Progressive Member
Progressive Member


Joined: 18 Sep 2009
Posts: 40
Location: New Delhi

PostPosted: Mon Jul 17, 2017 1:08 pm    Post subject: Reply with quote

Dear Hemal,

You pointed out very rightly the two distinct drift that the two different codes are based on.
It was my mistake. Thank you very much for highlighting it.

Best regards
Arun
Back to top
View user's profile Send private message Visit poster's website
SATYAPAUL
General Sponsor
General Sponsor


Joined: 18 Sep 2008
Posts: 127

PostPosted: Mon Jul 17, 2017 2:00 pm    Post subject: IS:1893-2016 Reply with quote

in case of any doubt,please follow american codes.because that they have more experience in high rise  buildings.we are the beginners. japan and Hong Kong codes shall also be studied. Singapore and Dubai  too has no adverse experience,WHEN AMERICAN CODES HAVE BEEN FOLLOWED BY THEM.OUR INDIAN codes are still  needs change.ANY HOW WHICH EVER IS SAFE SHALL BE FOLLOWED. REGARDS SATYA PAUL  On Mon, 17 Jul 2017 18:33:57 +0530 "hemalmistry"  wrote >                   Dear arun, >  >  > Drift limit for RC flat slab building according to indian code is 0.1% (0.001). While that according to  ACI318 is 0.5% (0.005). But, it should be noted that according to ASCE drift is inelastic drift, which  is R/I times elastic drift. So, permissible drift according to ACI is more, as inelastic drift is also  more. Plz not R as per ASCE is appx. 2R as per indian code. >  >  >  > Drift according to indian code is elastic drift and inelastic drift will be 2R/I. We are comparing  elastic drift with permissible limit. So permissible drift is less. There is no additional FOS as per  indian code. Actually, permissible drift is double that of ASCE, as inelastic drift as per indian code  is 2R/I times and not R/I times elastic drift. >  >  > Also, as per ACI352.1R, Drift limit for RC slab-column connection is 0.5% and that for PT slab-column  connection is 1.5% for gravity shear ratio (Vug/Fi*Vc) between 0.6 to 1, and higher drift is permitted  (some equations given) if gravity shear ratio (Vug/Fi*Vc) is less than 0.6. Even if drift is more than  drift limit (drift capacity of slab-column connection), punching shear reinforcement can be provided to  prevent drift induced punching. >  >  > Indian code only require to modify the structural system to control the drift. While according to ACI,  we can increase drift capacity of slab-column connection by controlling gravity shear ratio by  increasing flat plate thickness or by providing column capital or by providing drop cap or by  increasing concrete grade or by providing punching shear reinforcement.† >  >  >  > For indian code we can say that "We stop where other start". >  >  > Regards > Hemal Mistry > Surat >       > >  >  > --

Posted via Email
Back to top
View user's profile Send private message
sakumar79
...
...


Joined: 18 Apr 2008
Posts: 681

PostPosted: Mon Jul 17, 2017 2:00 pm    Post subject: Reply with quote

Dear Er Vijay,
    The ELX coefficient is boosted by 25% so, the factor 1.5 should become 1.25 x 1.5 = 1.875 and the factor 1.2 will become 1.25 x 1.2 or 1.5... Hope this makes it clear. I havent studied the use of the same under Dynamic Analysis.

Yours sincerely
Arunkumar
  
VIJAY N RATHOD wrote:
Dear Arunkumar,

Please clear my 2 doubt,  

(1)

I think load combination should be like this way ??

Shear walls need to take 100% of load ie, 100 kN instead of 80 kN.
Hence, the load combination factors for EQX need to be boosted by 25%.
1.5 DL + 1.5 ELX becomes 1.5 DL + 1.75 ELX
1.2 (DL + LL + ELX) becomes 1.2 (DL + LL) + 1.45 ELX

0.9 DL + 1.5 ELX becomes 0.9 DL + 1.75 ELX.

(2)


If the Dynamic Analysis carried out then you replace EQX with SpecX (DynX)??.


If yes then base Shear accumulated at the base. in my case i am having 5 basement.  So Design may be very heavy ??




thanks
vijay
Back to top
View user's profile Send private message
rahul.leslie
General Sponsor
General Sponsor


Joined: 01 Apr 2008
Posts: 493
Location: Trivandrum

PostPosted: Wed Jul 19, 2017 6:24 am    Post subject: Reply with quote

I think itís fairly clear:
1.5 DL + 1.5 ELX becomes 1.5 DL + 1.5*(100/80) ELX which is 1.5 DL + 1.875 ELX
1.2 (DL + LL + ELX) becomes 1.2 (DL + LL) + 1.2*(100/80) ELX, which is 1.2 (DL + LL) + 1.5 ELX
0.9 DL + 1.5 ELX becomes 0.9 DL + 1.5*(100/80) ELX which is 0.9 DL + 1.875 ELX

This idea was discussed a few years ago (but for the then codal clause) in:

http://www.sefindia.org/forum/viewtopic.php?p=61152

Rahul Leslie
Back to top
View user's profile Send private message Visit poster's website
elu
SEFI Member
SEFI Member


Joined: 27 Dec 2013
Posts: 1

PostPosted: Wed Jul 19, 2017 8:00 am    Post subject: IS:1893-2016 Reply with quote

Dear Sir,


We have follow the Indian code of Design only and need not required other code. but we will refer the other code for references please.


On Mon, Jul 17, 2017 at 6:33 PM, hemalmistry <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
           Dear arun,


Drift limit for RC flat slab building according to indian code is 0.1% (0.001). While that according to ACI318 is 0.5% (0.005). But, it should be noted that according to ASCE drift is inelastic drift, which is R/I times elastic drift. So, permissible drift according to ACI is more, as inelastic drift is also more. Plz not R as per ASCE is appx. 2R as per indian code.



Drift according to indian code is elastic drift and inelastic drift will be 2R/I. We are comparing elastic drift with permissible limit. So permissible drift is less. There is no additional FOS as per indian code. Actually, permissible drift is double that of ASCE, as inelastic drift as per indian code is 2R/I times and not R/I times elastic drift.


Also, as per ACI352.1R, Drift limit for RC slab-column connection is 0.5% and that for PT slab-column connection is 1.5% for gravity shear ratio (Vug/Fi*Vc) between 0.6 to 1, and higher drift is permitted (some equations given) if gravity shear ratio (Vug/Fi*Vc) is less than 0.6. Even if drift is more than drift limit (drift capacity of slab-column connection), punching shear reinforcement can be provided to prevent drift induced punching.


Indian code only require to modify the structural system to control the drift. While according to ACI, we can increase drift capacity of slab-column connection by controlling gravity shear ratio by increasing flat plate thickness or by providing column capital or by providing drop cap or by increasing concrete grade or by providing punching shear reinforcement.†



For indian code we can say that "We stop where other start".


Regards
Hemal Mistry
Surat
     



     



Posted via Email
Back to top
View user's profile Send private message
josephjenimt
SEFI Member
SEFI Member


Joined: 24 Nov 2013
Posts: 3

PostPosted: Thu Jul 20, 2017 8:33 am    Post subject: IS:1893-2016 Reply with quote

sir,I'm Joseph from Bangalore,finished my M.Tech in Structural engineering.I just want to know in what org. should i enroll myself to be an member of Structural Engineers.Shall i get my Structural engineer membeship number.plz guide me.thanx.


Joseph
Bangalore
8978507611




On 17 July 2017 at 18:33, hemalmistry <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
           Dear arun,


Drift limit for RC flat slab building according to indian code is 0.1% (0.001). While that according to ACI318 is 0.5% (0.005). But, it should be noted that according to ASCE drift is inelastic drift, which is R/I times elastic drift. So, permissible drift according to ACI is more, as inelastic drift is also more. Plz not R as per ASCE is appx. 2R as per indian code.



Drift according to indian code is elastic drift and inelastic drift will be 2R/I. We are comparing elastic drift with permissible limit. So permissible drift is less. There is no additional FOS as per indian code. Actually, permissible drift is double that of ASCE, as inelastic drift as per indian code is 2R/I times and not R/I times elastic drift.


Also, as per ACI352.1R, Drift limit for RC slab-column connection is 0.5% and that for PT slab-column connection is 1.5% for gravity shear ratio (Vug/Fi*Vc) between 0.6 to 1, and higher drift is permitted (some equations given) if gravity shear ratio (Vug/Fi*Vc) is less than 0.6. Even if drift is more than drift limit (drift capacity of slab-column connection), punching shear reinforcement can be provided to prevent drift induced punching.


Indian code only require to modify the structural system to control the drift. While according to ACI, we can increase drift capacity of slab-column connection by controlling gravity shear ratio by increasing flat plate thickness or by providing column capital or by providing drop cap or by increasing concrete grade or by providing punching shear reinforcement.†



For indian code we can say that "We stop where other start".


Regards
Hemal Mistry
Surat
     



     



Posted via Email
Back to top
View user's profile Send private message
Bilal Lakdawala
SEFI Regulars
SEFI Regulars


Joined: 04 Apr 2011
Posts: 20

PostPosted: Mon May 20, 2019 6:19 am    Post subject: Reply with quote

Dear Mr. Arun

I don't agree to your solution of making load combinations in single model to achieve codal requirement due to below mentioned concern.

By enhancing the load combinations based on comparing the values of reactions will provide the proper design of shear-wall just above base-level. But i think you should check the shear at the upper floor levels. Upper level walls will not be designed for 100%. Due to load path diversions to moment frame as well.

In my view separate model with all columns released at all floor level (both top & bottom) will only help you to design all floors shear-walls for 100% lateral loads.

Regards
Bilal Lakdawala



sakumar79 wrote:
Dear Sirs,
   IMHO, the easiest way to handle the codal requirement is to prepare separate load combinations for shear wall, perimeter frames and the internal columns.

   For example, let us consider an imaginary situation for EQX in a building where
a. the total reaction is 100 kN
b. reaction to supports of shear walls along X direction is 80 kN.
c. Reactions to perimeter columns along X direction is 10 kN.
d. Reactions to other columns is 10 kN.

   I would suggest the following methodology for design

a. Shear walls need to take 100% of load ie, 100 kN instead of 80 kN. Hence, the load combination factors for EQX need to be boosted by 25%.
1.5 DL + 1.5 ELX becomes 1.5 DL + 1.875 ELX,
1.2 (DL + LL + ELX) becomes 1.2 (DL + LL) + 1.5 ELX, and
0.9 DL + 1.5 ELX becomes 0.9 DL + 1.875 ELX.
    The shear walls along X direction shall be designed for these modified combinations along with the other standard load combinations for D+L and D+L+W.
     Adopt similar design load combinations for ELZ.

b. Similarly, for the perimeter columns along X direction, the 10 kN reaction needs to be boosted to 25 kN (ie, 2.5 times). Similar set of load combinations shall be prepared for the perimeter columns in Z direction

c. The internal columns can be designed for Dead, Live and Wind load combinations only.

     By this method, we will not only get results consistent with the codal requirements but it will also be easy to submit documentation to prove that we are complying with the codal requirement.

Yours sincerely
Arunkumar
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topicReply to topic Thank Post    www.sefindia.org Forum Index -> SEFI General Discussion All times are GMT
Goto page Previous  1, 2, 3  Next
Page 2 of 3

 

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


© 2003, 2008 SEFINDIA, Indian Domain Registration
Publishing or acceptance of an advertisement is neither a guarantee nor endorsement of the advertiser's product or service. advertisement policy