Optimal Structural System Selection and Placement for a High-Rise Concrete Building Affected by Earthquake Loads

Regular earthquakes and wind loads can inflict considerable damage on high-rise buildings. Therefore, various structural systems are utilized to ensure that these structures are safe in terms of lateral stress. To maintain safety during an earthquake, the building elements designed to resist lateral forces must be sufficiently rigid. Achieving high rigidity necessitates larger dimensions for columns and walls, which consequently reduces available floor space. Thus, designing efficient structural systems for this purpose is deemed essential for high-rise buildings. In this research, four structural systems were analyzed and compared using ten models in ETABS: the moment-resisting frame system, the moment-resisting frame system with a shear wall, the moment-resisting frame system with a bracing system, and the moment-resisting frame system with an outrigger system. The analysis reveals that combining concrete shear walls and outrigger systems significantly enhances structural stiffness and minimizes lateral displacements. Furthermore, the placement of these systems influences their performance and effectiveness. The combined use of these systems led to improved seismic performance and stiffness, particularly when the outriggers are located at the midpoint of the building's height. When the outrigger system is positioned at mid-height of the structure, the stiffness enhancement is 18 percent compared to when it is located at the roof level. The implementation of a core shear wall reduced drift by 69 percent compared to using a moment-resisting frame system alone, and the reduction increased to 81 percent with the addition of an outrigger system at mid-height.