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[chetan.solan]

Dear sefians

Is it right to adopt the practice to do ductile detailing only when adopt Response reduction factor =5   or IS13920  2000 is only for those detailing  in which you have taken response reduction factor R=5 ..... please explore this discussion ........
thanks
regards

[sakumar79]

Dear sir,
    Your question is not clear. But from what I understand, following is my reply.

1. For ANY RCC building located in Zones III, IV or V, ductile detailing as per IS13920 is must. If shear wall is provided, dual system with ductile detailing for both shear wall and frame should be adopted. If shear wall is not provided, then special moment resistant frame shall be adopted. In both cases, R=5.

2. In case of RCC building in Zone II, you have option of
(a) Ordinary or special moment resistant frame
(b) Ordinary or special shear wall with or without dual action (with dual action, it can be with ordinary or special moment resistant frame).
    Depending on the option adopted, R value has to be taken accordingly. If moment resistant frame is designed for earthquake forces as SMRF (with or without shear wall), ductile detailing as per IS13920 has to be done for the frame. Similarly, if the shear wall is designed taking R corresponding to ductile shear wall, ductile detailing as per IS13920 has to be done for the shear wall.

   Essentially, you have to ductile detailing as per IS13920 if you design the structure to behave in a ductile manner through consideration of Response reduction factor.

Hope that clarifies your doubt.
Arunkumar

[suresh_sharma]

Mr. Arun kumar,

I understand from your posting that that in zone ii ductile detailing would be necessary only when R value is chosen as 5, otherwise no. For Zone iii iv and v one has to compulsorily choose the R value as 5 and go in for ductile detailing. Have I understood you correctly?

[Dr. N. Subramanian]

Dear Er Chetan,

Ductile detailing is always better as will safeguard the structure against any accidental loading.

Best wishes,
NS

[prof.arc]

Ductile Detailing is ALWAYS GOOD even in very mild seismic zones.

The structure would have greater longevity
The small extra cost [compared to overall cost] is worth that money
 ARC

On Wed, May 23, 2012 at 12:02 PM, chetan.solan <forum@sefindia.org (forum@sefindia.org)> wrote:

[sakumar79]

Dear Er. Suresh Sharma,
      Let us not directly say that R=5 corresponds to ductile detailing. You can have ductile detailing for shear wall with ordinary moment resistant frame and the R value would be 4.5, you can have ordinary shear wall with SMRF for R=4, etc...

Case I: Zone is III, IV or V - Do ductile detailing of all RCC components (frame as well as shear wall, if present). Take R value as per code. As per current code,
    if no shear wall is provided, system adopted is SMRF with R=5
    if shear wall is provided, system is dual system with ductile shear wall and SMRF, R=5. Alternatively, system can be designed without ensuring that the frame takes minimum 25% of eq load. In that case, ductile shear wall system of R=4 will be adopted but frame should still be detailed as SMRF. This will probably be uneconomical compared to dual system and may be avoided.

Case II: Zone is II
      Any system as per Table 7 of IS 1893 can be used and corresponding R factor has to be adopted.


However, it is always better to do ductile detailing as recommended by Dr. NS sir, taking the corresponding R value from code.

Yours sincerely,
Arunkumar

[thirumalaichettiar]

Dear Er.Chetan,
IS there any reference in Indian code the ductile detailing is not needed if the different R values are used in the analysis? The vale R is to reduce the MCE so that the failure will be of structural and non structural failure.

In Eurocode it is classified the structures as Medium and High ductility and accordingly the detailing is little different. Vide EC8. But in Indian code the detailing is same but the design values are different.

You know why it is specified that flexural members should have Min. and max. steel ratio with 75% of balanced steel ratio. The underlying principle is to avoid brittle failure and have ductility. In beams do provide 0.2% bd as steel for hangers which will enhance the ductility and even reduce the deflection to some extent. This is method I follow since in some instances this will also help in acting as Doubly reinforced section.

Even if the structure is not in the seismic zone but with heay wind blowing area where the lateral wind load prevail can we leave the structure without ductility?

Can some seniors can elaborate on this aspect?

T.Rangarajan.

[shiven2004]

Dear Sefian ...

Is it will be not right practice to adopt specially for Zone -IV and V  that when you use MCE for design use R=5 and do ductile detailing .... and when you use DBE  take R=3 and do ductile detailing ......

But for Stability of Structure  use R=1 and do stability analysis as per DBE and MCE whichever you want to adopt ........

This clue is hidden is IS13920 :2000 that you have to design any projection on building by taking 5 times of seismic force ...

thanks
regards
Shivendra Kumar

[vikram.jeet]

Ductile detailing is always advantageous under EQ since it provides automatic Life insurance to  
occupants of buildins/and neighbours by preventing collapse of structure under severe EQ

The initial and one time premium paid is in form of incorporating ductile details provisions

By ignoring ductile detailing , the Framed rcc structure needs to be designed for 5/3(=1.67) times  
higher EQ Forces everywhere (long reinf, shear stirrups etc) and expenditure will be more than  
that by following ductile detailing.


I feel it is folly to neglect it. Some grey areas regarding difficulty in provisions at site can be  
overcome by educating the worksmen.

best regds

vikramjeet



Dear sefians Is it right to adopt the practice to do ductile detailing only when adopt Response reduction factor =5 or IS13920 2000 is only for those detailing in which you have taken response reduction factor R=5 ..... please explore this discussion ........thanksregards
-- ­­

Posted via Email

[ibarua]

7th June 2012

I don't understand the fuss about the necessity of ductile detailing in moment resisting frames of dual system buildings. What particular advantage do we get by NOT having ductile detailing?

Indrajit Barua.

From: prof.arc <forum@sefindia.org>
Sent: Fri, 25 May 2012 12:50:30
To: general@sefindia.org
Subject: [SEFI] Re: Ductile Detailing
           Ductile Detailing is ALWAYS GOOD even in very mild seismic zones.

The structure would have greater longevity
The small extra cost [compared to overall cost] is worth that money
ARC

On Wed, May 23, 2012 at 12:02 PM, chetan.solan <forum@sefindia.org (forum@sefindia.org)> wrote:
      --auto removed--

Posted via Email