The prediction of the exact behavior of multistory building is one of the most complicated problem encountered in structural engineering practice. An efficient computer method for the three dimensional analysis of building structures is presented in this paper. A multistory building is idealized as an assemblage of a series of rectangular plane frames interconnected by rigid floor diaphragms. The matrix condensation technique is employed for the reduction of degrees of freedom, which results in a significant saving in computational efforts and the required memory size.
Kinematical approach was used to assemble condensed stiffness matrices of plane frames into a three dimensional stick model stiffness matrix. The static analysis follows the modified tridiagonal approach. Since this procedure utilizes the condensed stiffness matrix of the structure, the dynamic equations of motion for the story displacement are developed by assigning proper mass for each story.
Analysis results of several example structures are compared to those obtained by using the well-known SAP IV for verification of the accuracy and efficiency of the computer program PFS which was developed utilizing the method proposed in this study.
The analysis method proposed in this study can be used as an efficient and economical means for the analysis of multistory buildings.
