Study on Natural Frequency of Frame Structures

Abstract

Moment resisting frame (MRF) structures are gaining popularity for their high lateral stiffness. This study investigates the parameters which affecting the natural frequency of moment resisting frame structures. Steel and concrete MRF structures were studied theoretically, analyzed numerically to obtain their mode shapes and frequency of vibration for each mode. From the theoretical and analytical results, a model equation for approximation of natural frequency of these types of MRF structures is proposed. The proposed model expressed the relationship of natural frequency of MRF structure with its total mass, lateral dimension in the direction of vibration and total height. The proposed equation will be helpful and easy to calculate the fundamental frequency for study on dynamic behavior of structures. Comparison between the current guidelines and proposed model is also discussed. The proposed model is satisfying the general concept of free vibrational response, and can be applied for analyzing small and full scale structures.