Orthotropic Membrane for Tall Building Analysis

A method for analyzing tall framed buildings based on the concept of equivalent elastic membrane is presented. The elastic properties of the membrane are evaluated taking into account the effects of finite size joints and axial deformations in the columns. Floors are assumed to be rigid in plane. The equivalent membrane is then analyzed using two-dimensional plane stress, specially orthotropic finite elements. The displacements thus obtained represent directly those of the actual structure, and the member forces are determined by integrating the corresponding stress components in the membrane. Two multistory multibay frames were analyzed, and the results show that a high degree of accuracy can be obtained with significantly smaller number of unknowns than by the exact and other simplified methods. The present technique can be readily applied to the static and dynamic analysis of tubed structures, clad multistory frames, and shear wall and frames structures.