Extract Of Design Guidelines For Architect / Developers Based On Draft Indian Standard ISI 6700-2017

Scope :

  • This code is applicable for reinforced concrete (RC) tall buildings such as residential, office and other commercial buildings.

  • This code may be used for design of medium and low rise buildings


Terminology:

Tall Buildings : 250m >Building Height > 45m

Medium/Low Rise Buildings : 45m >= Building Height




General requirements :

  • Plan Geometry


The plan shall generally be rectangular (including square) or (including circular). In buildings with said plan geometries, structural members participate efficiently in resisting lateral loads without causing additional effects arising out of re-entrant corners and others.






  • Plan Aspect Ratio

The Max. plan Aspect Ratio (=L/B) of the overall building shall not exceed 5.0




  • Openings


a) Openings in floor diaphragm shall not be permitted along any floor diaphragm edge, unless perimeter members are shown to be have stability and adequate strength.






b) The maximum area of openings in any floor diaphragm shall not exceed 30% of the plan area of diaphragm




c)

i) At any storey, the minimum width of floor slab along any section after deduction of openings shall not be less than 5m.

ii) And the minimum width of the slab beyond an opening to edge of slab shall not be less than 2m.

iii)The cumulative width of the slab at any location shall not be less than 50% of the floor width.





  • Materials

a) Concrete

Min. Grade = M30

Max. Grade = M70

(When higher grades are required, the designer shall ensure through experimentation that such concretes shall have at least a minimum crushing strain in compression of 0.0020.


The grades of concretes used in slabs and beams shall not be less than 70% of that used in columns and wall in contact.


When grade of concrete used in columns is different from that used in beam & slabs beyond the above limit, concrete used in columns and walls shall be used in the beam-column joints also. In such a case puddling of concrete (shall be placed in the beam/slab at column location for a min. of 0.6m from column face) shall be done. Such concrete shall be well integrated with the beam/slab concrete.(Fig. 7)




b) Reinforcing Steel


b) Reinforcing Steel The characteristic yield strength of the steel reinforcement bars used in construction shall not exceed 1.2 times the value used in design. The ultimate strength of reinforcement bars shall not exceed 1.25 times the characteristic yield strength. No lapping of bars shall be allowed in RC beams, columns and walls, when diameter of bars is 16mm or higher, mechanical couplers shall be used to extend bars.


  • Non-Structural Elements


a) Non-Structural elements, such as curtain walls, cladding,partitions and finishes and service installations (e.g. elevators, vertical pipes, ducts and cables), shall be required to withstand long-term movements of the building and associated differential effects.


b) Details of connections of non-structural elements with the structural elements of the building shall be planned, such that their relative movements are allowed without causing distress to both structural and non-structural elements.


c) Appropriate vertical compensation and sway compensation shall be accounted for during construction to minimize long-term building movements for concrete and composite structures.

  • Framing system

a) Transfer structure shall not be provided at the first connected floor.



b) Frame structure for seismic design shall have at least two planer frames with min. 3 bays in the direction where the lateral load resistance is provided by the moment frames.



c) The Min. Dimension of a column shall not be less than

i. 15 times the largest beam bar diameter of the longitudinal reinforcement in the beam passing through or anchoring into the column joint, and

ii. 300mm




d) The thickness of structural wall shall not be less than 160mm or hw/20, whichever is larger. (applicable for Seismic zone other than IV and V)




e) For Seismic zone IV and V, i)Special moment frame and shear walls shall not be discontinued in lower stroreys and supported on less stiff and brittle elements.




ii)The thickness of structural wall shall not be less than 200mm.





Disclaimer Since the draft is at suggestion / objection stage, The contents of this documents to be used judicially.

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