Evaluation of Free Vibration Characteristics of Steel Space Frames

ABSTRACT:The design of structures subjected to natural hazards such as earthquakes and typhoons demands safety of structures which is governed by the natural frequencies and the amount of damping in each mode of vibration. Fundamental frequency of a building and its damping have a remarkable effect on the magnitude of its response. The ability to predict these characteristics at the design stage would enable to design safe structures.This paper presents the numerical and experimental dynamic characteristics of steel moment resisting space frames. An experimental investigation was carried out on a small-scale (1:15) 3-storey moment resisting steel frame and its fundamental frequencies are obtained. A numerical simulation of the model was performed using the finite element analysis.The numerical results of the model are compared with the experimental results. Numerical studies are extended to find the influence of the plan and bay dimensions, normalized stiffness and height of storeys of multi bay multi storey frames on the fundamental frequency of the moment resisting frames. Based on the experimental and the numerical investigations, the free vibration characteristics of moment resisting steel space frame are established.