Simple Analysis of Tube Frame System of Tall Building by Using of Deformation Functions

According to increase of population in cities, tall buildings have been become interesting and fascinating for urban managers and engineers. Tubular frame structure is one of the most efficient systems in tall buildings under lateral load. The analysis of these structures usually involves considerable time and effort due to large number of members and joints. Several methods for evaluating shear lag and estimating stress of frame elements are presented recently. According to one of these methods, tube frame is assumed as a web and flange panel and then by considering deformation functions for web and flange frames and writing their stress relations as well as use of minimum energy basis, functions are presented for lateral and vertical displacement of the structure. Two relation groups suggested in this paper are capable of considering shear lag both in flange and web frames in the base of frame. The simplicity and accuracy of the proposed method is demonstrated through the numerical analysis of several structures. In addition, the results of these proposed deformation functions are compared to previous relations considered by other researchers to find the best relations.