Correct Answer - Option 2 : 1.089 seconds
The fundamental natural period of vibration for steel frame building having a height of building 30 m is 1.089 seconds. IS 1893(Part 4)- 2005 provides some guidelines for the calculation of the time period of the structure.
Time Period Estimation:
The time period of different industrial structures would vary considerably depending on the type of soil, span and height of the structure, distribution of load in the structure, and the type of structure (concrete, steel, and aluminum). It would be difficult to give one or two generalized formulae to cover all such structures. Accordingly, no simple guidelines can “be given for estimation of time periods of industrial structures.