IS 16700-2017: Clause 5.3 Stroey Stiffness and Strength

Intention:
To help students and practising engineers understand IS Code Provisions.
References:
IS 16700-2017 Criteria for Structural Safety of Tall Concrete Buildings.
IS 1893:2016 Criteria for earthquake resistant design of structures
IAStructE Code and Commentary on IS 1893 Criteria for Earthquake Resistant Design of Structures Part 1 General Provisions and Buildings (Sixth Revision)
BMTPC Earthquake Tips
GSDMA Document Proposed Modifications and Commentary for Code on Criteria for Earthquake Resistant Design of Structures IS 1893: 2016 (Part 1- General Provisions and Buildings)
NPTEL Lectures on Structural Dynamics by R. Pradeep Kumar. nptel.ac.in/co...
Acknowledgements:
The support of students in the preparation of the slides is sincerely acknowledged.
Thank you,
R. Pradeep Kumar

[@mallikarjunatkalamma]

Thank you sir

[@gnanavelkanniappan8637]

Nice 👍

[@mairajhabib9754]

in lecture explained, how prog calculates k value.
But how strength to be cross checked wrt to upper floors.

[@adityashrestha8549]

Please explain how to calculate the lateral shear strength of a storey for WEAK storey check. Code does not give any methodology.

[@eboy4686]

Dear Teacher, In IS-1893, the stiffness and strength irregularity building frame appear to have the same diagram, in which one of them shows complete removal of a column; so, my question is can I refer to this type of irregularity as "combined stiffness and strength irregular building frame"? And How calculations of strength irregularity are done in commercially available software?

[@pulkitvelani]

Diagrams are for represention purpose to explain some concept. The objective of that diagram is to show difference in stiffness between two consecutive floors. However, your reference of considering them for both irregularities can also be true but not always true. Detailed investigation is required to reach to that conclusion. Since, for both stiffness and strength irregularities respective values (ratio) should be satisfied to declare the building as having particular irregularities.

[@mairajhabib9754]

Why code permits 0.7k(i+1) ?
How 70% arrived ? What is the basis of it. pl suggest literature.
Infact, lower lvl k shall never be permitted on lesser side wrt upper lvl.

[@pulkitvelani]

Not sure about the 0.7 value but Tall buildings usually have ground storey with height more than the height of typical floor. Such architectural practices will surely introduce the difference in storey stiffness (lower stiffness of such ground storey). Hence, code committee in India and around allow difference of 30% in stiffness.

[@mairajhabib9754]

@@pulkitvelani your point sounds ok wrt Ground and First floor.