Presenting a quick method for estimation of MRF dynamic characteristics using 3D modeling

The current research presents a quick method for estimating the lateral stiffness and torsional stiffness of 3D MRF (moment-resistant frame) structures, considering irregular moment frames. This study also provides a method for calculating story displacement and rotation and natural frequencies with respect to different lateral load patterns. This study proposes a method for calculating lateral and torsional stiffness for each frame in two directions, and then converting the stiffness of all frames to one frame to obtain the deformation and natural frequency for two directions. The basic idea of the proposed innovative method was developed through the force method to obtain the lateral deformation and stiffness of 2D building structures. Then, the mentioned procedure was expanded into 3D building structures. Some examples have been made to compare the latter method with linear analysis. The results showed that the suggested method can capture 3D dynamic characteristics with accuracy compared with linear analysis.