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[hemalmistry]

Dear SEFI members,

According to IS:16700_2017, all buildings with height exceeding 250 m, buildings that houses more than 20000 people are code exceeding buildings. Guidelines (in addition to that given in ANNEX A) shall be available for such code exceeding complicated buildings as given in JGJ-3_2010.
As mentioned in "FORWARD"  of the code to IS:16700_2017, JGJ-_2010 (Technical specification for tall building concrete structure- china) is one of the international standard referred in our code. From the quick review of this code, i can say that this is an excellent chinese product (code). There is no code exceeding building in this standard except near fault buildings. Guidelines (minimum 2 page) are given for almost all structural system including that for complicated structures like structure with transfer story, structure with outriggers and/or belt member, buildings linked with connective structure, building with staggered floors, building with setback and/or cantilever etc. All residential buildings with more than 10 floor, other building with height more than 28 m comes in scope of this standard and buildings below this limit shall be designed with GB50011_2010.
Even the content of the code as given below is impressive.

1 General Provisions
2 Terms and symbols
2.1 Terms
2.2 symbol
3 Basic requirements of structural design
3.1 General Requirements
3.2 Materials
3.3 Height and aspect ratio limitations
3.4 Structural plan layout
3.5 Structural vertical arrangement
3.6 Diaphragm system
3.7 Limitations of story drift and comfort
3.8 Strength design of members
3.9 Seismic design grade of structural members
3.10 Requirement for members of special seismic design grade
3.11 Performance based seismic design of structures.
3.12 Requirement for  preventing structural progressive collapse
4 Loads and Seismic action.
4.1 Vertical load
4.2 Wind load
4.3 Seismic action
5  Structural analysis
5.1 General Requirement
5.2 Analysis parameters
5.3 Analysis and Modeling
5.4 Second-order effects and structural stability
5.5 Elasto-plastic Analysis and Check of Story drift of weak and/or soft stories
5.6 Effect of combinations of load and/or seismic actions
6 Design of frame structure
6.1 General Requirement
6.2 Strength Design
6.3 Requirement for detailing of frame beams
6.4 Requirement for detailing of frame columns
6.5 Requirement for splices and anchorages of reinforcement
7 Design of shear wall structure
7.1 General Requirement
7.2 Strength Design and detailing
8 Design of Frame-shear wall structure
8.1 General Requirement
8.2 Strength Design and detailing
9 Design of Tube structure
9.1 General Requirement
9.2 Frame-core wall structure
9.3 Tube in Tube structure
10 Design of complicated tall buildings
10.1 General Requirement
10.2 Structure with Transfer story
10.3 Structure with outriggers and / or belt member
10.4 Structure with staggered stories
10.5 Towers linked with connective structure
10.6 Structure with setback and/or cantilever
11 Design of mixed structure
11.1 General Requirement
11.2 structural layout and arrangement
11.3 Structural Analysis
11.4 Design of structural member
12 Design of basement and foundation
12.1 General Requirement
12.2 Design of Basement
12.3 Design of Foundation
13 construction of tall buildings
13.1 General Requirement
13.2 Surveying
13.3 Foundation
13.4 Vertical transportation
13.5 scaffold and Falsework
13.6 Formworks
13.7 Steel Reinforcement
13.8 Concrete
13.9 Massive Construction
13.10 Mixed structures
13.11 Complicated structures
13.12 Construction Safety
13.13 Green Construction
Appendix Calculation of acceleration of the floor _vertical vibration
Appendix B wind pressure coefficients of buildings
Appendix C Horizontal earthquake Calculation with Equivalent base shear  method
Appendix D Check of stability of structural wall
Appendix E Lateral stiffness requirement of stories adjacent to transfer story
Appendix F Design of concrete filled circular steel tubes
F.1 Design of structural member
F.2 Design of connection
Explanation of wording in this specification
List of quoted standards

Regards
Hemal Mistry
Surat

[Sanjay_Puranik]

Why don't our eminent code writers simply add a statement to the effect that the user is free to follow the best international practices?  
In any case most of our codes are a hotch-potch and mish-mash of international codes and some home-grown ideas(often absurd) …..how much of what goes into our codes is based on our own research?  

1. Isn't the new IS 800 :2007 a copy of the European steel code? There is a chapter on working stress design but id working stress design allowed? The code is silent.  
2. Response reduction is 4.5 for special braced frames and 4 for ordinary braced frames (corresponding values are 6 and 3 in AISC) what is the difference ?  
3. Let us for arguments sake take two structures in zone 3 that are exactly identical (bracing is V) but one has I=1.5 and the other I=1 one with lesser I has 11 % more mass. With this the seismic forces will be almost equal. One with I=1.5 has zipper columns and the one with I= 1 doesn't. with almost identical member sizes , the I=1 structure will be at risk for given ground motion.  
4. Why is cracking limit state applicable under transient conditions? Many codes co-relate bar spacing, stress and crack-width. IS 456 does this + gives a formula for crack width calculation . Why?  
5. In a column we can leave a bar untied if bars on both sides are tied in both directions and are not more than 75 mm from the untied bar. In most coders the limit is 150 mm…with 75 mm limit a column with say 10 bars on each face will be impossible to pour unless we use polygonal links.(which are difficult to make)  
6. IS 800 mentions “prying if applicable” for base plate design. Don't they know that prying will generally not occur for foundation bolts? Where is an engineer supposed to look for guidelines for this? Have the code writers feel that they can get away making vague/incomplete statement because they are assuming that anyone who is in confusion will anyway GOOGLE?  

Regards  Sap    From: hemalmistry [mailto:forum@sefindia.org]  Sent: 13 March 2018 11:27  To: econf@sefindia.org (econf@sefindia.org)  Subject: [E-CONF] FOREWARD IS 16700-2017     Dear SEFI members,   According to IS:16700_2017, all buildings with height exceeding 250 m, buildings that houses more than

Posted via Email

[venkatarangarao]

Inputs-IS 11600-RR My inputs kindly review and respond.

1.3 Is this a group pf buildings or a single building? Why is this applicable?
1.4 Clause says this code may be used for less than 50m. It becomes a clash with design practices done with IS 1893 etc. Though next clause provided explanation, better to avoid cross references for the lower bound    
  
What is the need for the underlined statement?
Is the head room included as most of the structural walls may have been terminated?    


Code should qualify the location of shear wall as often times, code walls are highly eccentric to center of mass and brings in torsion    
  
In reality, most of the modes are coupled modes and not truly fundamental modes. What is the further criteria?    
  
Is the screed reinforcement required to be structural connected to peripheral beams or a simple unconnected rebar mesh is sufficient?    
  
What is the criteria- unsupported length of the opening / slenderness limit/ axial force ?
As we are using rigid diaphragm in most cases, this does not effect the analysis    
  
Basis of an acceptable method ?

  
We have excitation under moving/ walking activities. How do get accelerations for static gravity loads?

  
What about the descending part of the curve? We need to relate to both to have dual criterion.    
  
Why two criterion?    

5.8.2 : Key elements – Further explanation is required. For example, if column is a key element, we need to limit Pu/Puz etc.

Posted via Email

[ajay2612]

Good points raised sir

From: "Sanjay_Puranik"forum@sefindia.org
Sent:Tue, 13 Mar 2018 13:22:34 +0530
To: econf@sefindia.org
Subject: [E-CONF] Re: FOREWARD IS 16700-2017
           Why don't our eminent code writers simply add a statement to the effect that the user is free to follow the best international practices?

[hsrai]

[hemalmistry]

Thanx for the correction sir