Alternative Design of Mega Structural Members of a Super-tall Building using 800MPa Grade High-performance Steel Plate

Abstract

HSA800 is a new high strength steel (HSS) plate for building structures developed by POSCO and RIST in 2011. It has upper and lower bounds for yield (Fy) and tensile (Fu) strength as of 650-770MPa and 800-950MPa, respectively, with yield ratio (Fy/Fu) limit as of 0.85 which make steel quality more reliable and enhance the seismic resistance of structures. As made by TMCP, it has a good weldability without increasing carbon percentage. The objective of this study is to provide alternative design of mega-structural members of the Lotte World Tower (555m, 123 story), a first super-tall building in Korea, using HSS considering structural safety, constructability, and cost-effectiveness. Steel outrigger trusses, belt-trusses and steel exterior columns were selected and analyzed to evaluate the structural performance between original and alternative designs using HSS. The results show that HSS can be applied to the members which do not affect lateral stiffness of a building and, in this study, approximately 1100tons of steel were saved. It implies that HSS can save overall construction costsmanufacturing, delivery, and erection costsby reducing mega structural member size. HSA800 was very first applied to the Lotte World Tower based on the results of this study.

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“…The high-performance structural steel of HSA800 has advantages from the structural aspect, including compactification of structural members, minimization of member sizes and self-load reduction of buildings [36]. In addition, it has various benefits, such as reduction of materials cost, as a result of the reduction of the cross section of members, securing transportation, lifting, and usable spaces [37].…”