Fundamental Period of Buildings

 

Fundamental Period of Buildings

If the distribution of mass and stiffness along the height of a building is known, the period of vibration can be determined . For design purposes, the fundamental period can be easily estimated using Rayleigh's Energy method 

There are several empirical formulae available for estimating periods of buildings. Among them, a widely used one for moment resisting frames without bracings or shear walls is

 

T = 0.1N sec                                                   ...(a)

Where N is the number of storeys. Another formula which may be applied generally is

 

T = 0.09 H/SQRT D                                          ...(b)

Where H is the height in metres and D is the dimension of the building in metres in a direction parallel to the applied seismic force.