Reza Rahgozar - Associate Professor, Department of Civil Engineering, Shahid Bahonar University of Kerman
Zahra Mahmoudzadeh - Graduate Student of Civil Engineering, Department of Civil Engineering

The focus of this article is to present a simple mathematical model to determine the natural frequencies of tall buildings which consist of framed tube and shear wall systems. The analysis is based on the continuous approach, in which a tall building structure is replaced by an idealized cantilever continuous beam representing the structural characteristics. The governing equations of free vibration and corresponding eigenvalue problem are derived based on the energy method and Hamilton principle. Applying the separation of variables on time and space, natural frequencies have been obtained. A computer program has been developed in MATLAB and two numerical examples are performed. The results obtained from the proposed method are compared with SAP2000 which give reasonably accurate and hence suitable for quick evaluations during the preliminary design stages

tall building, framed tube, shear wall, free vibration, natural frequencies