DETERMINING THE OPTIMUM LOCATION OF TWO-FLEXIBLE OUTRIGGER SYSTEMS IN TALL BUILDINGS USING ENERGY METHOD

Abstract

Construction of tall buildings has been rapidly increasing worldwide, introducing new challenges that demand rigorous engineering. Structural and nonstructural damage to tall buildings can be minimized by implementing appropriate lateral resisting systems, such as the outrigger and belt-truss system. The location of outrigger and belt-truss systems plays a critical role in the behavior, structural integrity, safety, and overall construction cost of tall buildings subjected to lateral loads; thus, they should be selected carefully. This research develops a framework that can determine the optimum location of two flexible outrigger and belt-truss systems in skyscrapers subjected to uniform lateral loading. To achieve this goal, an energy method is applied to maximize the outrigger and belt-truss system’s strain energy. In this approach, the framed tube and effect of outrigger and belt-truss systems on shear core are modeled as a cantilevered hollow section beam with orthotropic plates and rotational springs placed at outrigger and belt-truss location respectively. The optimal location is determined where the rotational spring absorbs the most amount of energy; and this is accomplished by setting the first derivative of the energy equation with respect to the spring’s location, as measured from the structure’s base, to zero. The practical graph developed in this research can aid engineers during the preliminary design of tall buildings for quick calculation of the optimum locations of outrigger and belt-truss systems.