Difference between ASCE-07 and IS 1893-2002 Part I

[sagarmjadhav]

Hi guys,
I am currently comparing ASCE-07 and IS 1893-2002 Part I ,and designing 12 storey building in both USA and INDIA as a part of my project.I want you guys to help me with some questions mentioned:

1) There is no provision in IS 1893 which states that for analysis we should use cracked moment of inertia of concrete beams and columns.Where as ACI-08 does give minimum cracked section inertias as Ic=0.7Ig for columns ans Ic=0.35Ig for beams.So what should be done in case of Indian code?should we use gross(Ig) wont it be on a conservative side?
2) Also according to storey drift clause 7.11.1 the 0.004 H minimum storey drift refer to elastic or inelastic deformation?,For ASCE-07 a factor Cd is multiplied to the elastic deformations to get inelastic deformations.

Also for storey drift which load combination should be used?

 

[DST148]

1) The material properties to be used in the analysis is typically given by the codes / standards pertaining to that material. If there are no guidelines, you may analyze first without any reduction in stiffness and later with 50% stiffness for all the elements to account for cracking. Of course, this is a very simplified and crude way.
2) Ref ASCE 7-05. Seismic is more about strength and stability and therefore there are no serviceability deflection criterion per se. The drift is calculated under strength level seismic forces based on the computed period of the structure without the upper limit Cu.Ta specified in Section 12.8.2. The amplified drift is obtained by multiplying by Cd / I and compared with allowable story drifts as given in the Table 12.12-1. There is no load combination for checking drift, just the strength level seismic forces calculated using Section 12.8.6.2.
However, a drift analysis is not complete without performing a P-Delta check for which you can refer to section 12.8.7.