Reducing static roof displacement and axial forces of columns in tall buildings based on obtaining the best locations for multi-rigid belt truss outrigger systems

Abstract

In this paper, energy method as a robust method has been used to compute the optimum locations of belt truss and outrigger systems. To achieve this aim, a tall building of constant stiffness along its height, reinforced with a framed tube, shear core and belt truss with outrigger systems has been considered. An equivalent cantilevered beam has been used to model the framed tube system. Here, outrigger–belt truss systems are modeled by rotational springs placed at their spatial position. Utilizing the energy method, belt truss systems are placed at particular positions along the structure’s height, selected so to maximize energy absorption and dissipation. Applicability and accuracy of the proposed method are verified via a numerical example (50-story concrete building) and the results are compared with Stafford Smith’s method. The proposed method demonstrated for several belt truss and outrigger systems a reduction in the values of the roof displacement and axial force in comparison with Stafford Smith’s method. The results show that the structure with two belt–outrigger systems has a better performance in reduction of roof displacement and axial forces (2.3% and 4% reduction, respectively) rather than the one- and three-belt truss systems.