| dc.description.abstract | The determination of the fundamental period of vibration of a structure is essential to
earthquake design. Current code equations (US 319:2003) provide formulas for the
approximate period of generalized earthquake-resistant building systems, which are dependent
on the height of the structure. Such a formulation is inadequate for various structures with
lateral support mechanisms, inadequate for heights of structures above 20m for steel and
heights above 30m for concrete frames. Additionally, its unable to account for structures with
differing geometric irregularities.
This study investigated the fundamental periods of different types of steel and concrete
earthquake-resistant building structural models: steel moment resisting frames (MRF), steel
concentrically braced frames (CBF), reinforced concrete (RC) structures with and without
shear walls with varying geometric irregularities. A total of 24 MRFs, 12 CBFs, and 18 RCs
were designed and analyzed with ETABS v.17.
The fundamental periods based on vibration theory (Rayleigh equation) for each model were
compared with empirical equations provided in the current code (US 319:2003). Based on the
results obtained from vibration theory, equations for the approximate fundamental periods are
put forth for MRFs, CBFs, RCs with shear walls and without shear walls which consider
vertical and horizontal irregularities.
Through statistical analysis (regression) using Datafit v.9.00 and comparison, it was found that
a coefficient single-variable power model with consideration for irregularities resulted in a
better fit to the Rayleigh data than the code provided empirical equations. The proposed
equations were validated through a comparison of available measured period data against
results based on vibration theory.
Finally, conclusions from our observations of results and recommendations were recorded
down. | en_US |
