A Rational Approach for Fundamental Period of Low and Medium Rise Steel Building Frames

The fundamental periods of buildings are essential to calculate the design base shear and lateral forces. Most seismic codes specify empirical formulae to estimate the fundamental vibration period of buildings. These empirical formulae are used for both lowand mediumrise buildings. These formulae depend on the building materials (steel, reinforced concrete etc), building types (frame, shear wall etc) and overall dimensions of the buildings. In this paper, for finding the fundamental natural period of steel moment resisting frames, numerical studies are carried out, and by regression analysis, empirical formulae are derived for lowand mediumrise buildings. The numerical studies carried out includes, the influence of the plan and bay dimensions, normalized stiffness and height of storeys and various cross sections as columns and beams on fundamental period of the moment resisting frames.