What are the Stability checks criteria for the High rise building?
The criteria for the stability checks for the tall
buildings are as follows: -
- Inter
storey drift ratio should be less than 0.004. (Clause 7.11.1.1 of IS
1893(Part 1): 2016
- The maximum deflection
against wind allowed is H/500. (Clause 5.4 of IS 16700:2017)
- Maximum deflection against EQ allowed = H/250. (Clause 5.4 of IS 16700)
- Maximum
deflection against cantilever or any individual element allowed = span/350 or
20 mm whichever is less. (Clause 23.2.B of IS 456:2000).
- Guidelines for
fundamental time-period = 0.1 * N (N= No of levels)
- No.
of modes given should be given in such a way that around 95 to 98% modal
participating man ratio shall be achieved. (Clause 7.7.5.2 of IS1893 (Part
1): 2016.
- 1st mode of vibration is preferred to be in translation mode. (Clause 5.5.1 of
IS16700: 2017)
- If
the frequency of the building is less than 1Hz then wind dynamic analysis needs
to be done by considering the guest factor. (Clause 9.1 of IS875(Part 3)
:2015) and for the Dynamic wind, response refers to chapter 10 of the same code describe at this point.
- For key elements
(elements acting as transfer beams) design over strength factor of 1.5 need to
be used for EQ loadings. E.g.: Load
combination (Additional factor of 1.5 need to be multiplied for EQ load case
for the following load combinations)
- 1.5D + (1.5 * 1.5) E
- 1.2D + 1.2 L +
(1.2*1.5) E
- 0.9D + (1.5*1.5) E
- If
the expansion joints are there in the building the distance of expansion joint
need to be as per (Clause 7.11.03) of IS1893 Part 1-20
- All the structures
elements need to well within the strength design limit criteria.