Selecting Optimal Dimensions of Internal Tube in Tube-In-Tube Structural Systems Based on Structural Parameters

Tubular structural systems are one of the most common types of systems in high-rise structures. in the early days of this system, there were imperfections in its design which were overcome over time. the most important modification to rectify these defects is the use of a series of internal frames in addition to the peripheral frames and new systems in the center of the plan to eliminate design weaknesses over time. the central frames such as the inner tube, enhance the final rigidity and durability of the system. in this paper, high-rise buildings of 30, 40 and 50 floors have been subjected to static linear analysis and resistive design and their key design parameters have been investigated. the method is in a way that several samples with real dimensions are selected and the variables of height and the inner tube dimensions are numerically compared. the results revealed that the inner tube dimensions play an important role in improving the design parameters and the best dimension of the inner tube in a square plan is equal to half of the dimension of the outer tube.