The Use of Core and Outrigger Systems for High-Rise Steel Structures

With increases in building heights, understanding the effectiveness, advantages, and limits of different structural systems to resist lateral loads is crucial. Such tall buildings rely on moment frames, braced steel cores, concrete shear walls, outriggers, and bundled boxes to resist their lateral loads in addition to their gravity loads. In this investigation four structural models were created using STAAD Pro CONNECT Edition (moment frame, moment frame and a braced core, moment frame plus outriggers on the top and outriggers at 1/3 height) to compare the effectiveness of each system. According to this study, using a braced core in conjunction with a moment frame reduced the lateral displacements by 24% and 26% (with respect to the two lateral directions) as compared to using moment frames alone. Similarly, the outriggers systems reduced the lateral displacements but less than obtained by using the braced core system. When comparing the steel weight of the four different systems, the outriggers models have the least weight, therefore the cheapest. The lightest steel frame (lighter by 3184 kips) was obtained when using the outriggers at 1/3 of the building heights