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[sefi_admin]

Dear All:

Greetings and welcome to the E-conference on "IS 16700- Criteria for Structural Safety of Tall Concrete Buildings". As mentioned earlier this conference will discuss Sections of the code day-wise.

Date Section
13/3 Sections 1 to 6
14/3 Sections 7 and 8
15/3 Section 8
16/3 Sections 9, 10
17/3 Section 11 and Annexures
18/3 All other general queries about code and Concluding Session
19/3 Clarifications Note from Moderators. (No Econference on 19/3)

If you miss any of the days deliberations and wish to ask queries on a section which has already been discussed, you have an opportunity to do so on March 18. Kindly do not discuss other than scheduled section until March 18.

Today we will be discussing the code from Sections 1 to 6.

Section 1 is regarding the Scope of the Code. Section 2 is on the underpinning reference codes. Section 3 and 4 refer to terminology and symbols respectively used in the code.

Section 5 is an important prescriptive section on General Requirements.
它不同struc的高度限制tural systems based on the seismic zone, the max aspect ratio (height/least plan dimension at base) for difference structural systems and requirements of storey stiffness and strength.
Section 5 stipulates drift limits under wind and earthquake load conditions and the acceptable modes of vibration.
Section 5 discuss use of precast slab elements and stipulated the limitation for openings in a diaphragm slab. There are limitations specified on concrete strength imposed and requirements of mechanical couplers for bars in vertical members.
Section 5 also makes passing reference to progressive collapse mechanism and key element design approach.

Section 6 deals with Loads and Load Combinations.
It specifies conditions under which Wind Tunnel studies are mandated and defined the min base wind shear to be used for design. New limits for lateral peak acceleration at uppermost level are introduced. Further some relaxation in min base shear for earthquake design for buildings over 200 m has been introduced.

Kindly note that the discussions are amongst the SEFI community. We will not be interfering in our capacity as moderators except to occasionally participate in our individual capacity. Here's wishing a very productive discussion on the relevant Section(s) of IS 16700!




Best regards,

Econference Moderators


Posted via Email

[mlnrao]

Clarity to be given as mentioned in FOREWORD of tall building code whent to follow Annex A for buildings less than 250m and what are guide lines.
Rgds
M.Laxmi Narasimha Rao

[DEYABHILASH]

Dear Admin� � � � Please post the updates of e conference by email or any broucher or videos.




On Tue, Mar 13, 2018 at 7:18 AM, sefi_admin forum@www.buonovino.com)> wrote:

[bsec]

Dear All,

I express my sincere thanks at the outset to SEFI admin for their decision to hold an e-conference on this important topic. This has become relevant in light of the recent publication of BIS code IS:16700-2017. I have quite a few observations / comments on this code which are as follows :

Foreword :

a. � � Many international publications have been referred in the FOREWORD, which has been referred to by the code makers in formulating this guideline. There is an excellent fib state of the art report, named Bulletin 73, titled “Tall Buildings Structural design of concrete buildings upto 300m tall” available. Reference should have been made to this very important document while framing this guideline.�

b. � � Unlike normal buildings, Tall Building design and execution involves close design interface and collaboration between structural engineers and architects, façade engineers, wind specialists, seismic specialists, geotechnical specialists, fire consultants, lift specialists construction advisors ensuring buildability and finally the clients. Optimisation of structural design of Tall buildings is possible only when the functional aspects and usage of the building are decided keeping the structural behaviour in mind. This aspects should have been emphasised in the code in some form ….may be in FOREWORD.

Section 1 : Scope

a. � � The code only covers tall buildings made of concrete. Tall Building code is incomplete without covering all potential materials of construction. Steel and Composite materials has immense potential in tall buildings, from consideration of sustainable development and should have been covered also in this code. Choice of structural system for any tall building must explore all possible options of material use.

Section 5 : General Requirements

a. � � As per Table 1 and Table 2, Moment Frame System is not applicable for buildings in seismic Zone IV and V. Basis for eliminating framing system altogether in high seismic zones is not made clear. This may require a review. As per fib bulletin-73, framing system is permitted in tall buildings upto a height of about 75m. This clause therefore should be reviewed.

Section 6 : Loads and Load Combinations

a. � � Design of Tall building is highly construction driven. Therefore consideration of construction stage loads in the design process is a must. This should have been made clear in this section of the code.

b. � � Tall buildings should be designed for avoiding disproportionate impact and Progressive collapse in case of an accidental event. There has been several noted cases of progressive collapse of this nature in the past and there should be provision in the code for robustness in design to prevent such failures.

c. � � �IS:875 Part 3 is perhaps inadequate for design of Tall Buildings, which are highly wind-sensitive structures. Current approach to consider elastic behavior�of tall buildings under critical wind loading (while allowing in-elastic behavior�under seismic) is perhaps a conservative approach. Recent presentation by Prof Peter Irwin of RWDI, Canada reflects this concern.

Best Wishes


Alok Bhowmick


On Tue, Mar 13, 2018 at 7:18 AM, sefi_admin forum@www.buonovino.com)> wrote:

[Ranjith.Chandunni]

Dear Mr. Alok Bowmik,


We note your comments and observation on the Tall Building Code provisions during the Day 1 of the discussions. Thank you very much.

They are quite relevant and certainly need attention. We will be discussing these in the meeting of the drafting group and see how best they can be incorporated in to the code.

Best regards,

E-Conference moderators