Structural Systems for Tall Buildings

Abstract

Structural systems for tall buildings have gone through an evolutionary process. The rigid frame became popular in the first half of the 20th century but proved to be structurally inefficient beyond a certain height of tall buildings. The invention of the tubular structure in the 1960s allowed buildings to be built taller with low material consumption. Due to the obstructive nature of the closely spaced exterior columns of framed tubes and bracings of braced tubes, the core-outrigger system gained acceptance by the architects as it allowed them to freely articulate the façade design. However, the conventional tubular structures continued to retain their use for tall buildings to a lesser degree and later underwent a resurgence in modified forms. These and other advanced tubular forms in cutting-edge structural systems developed later continue to find application in modern times. This study presents a detailed narrative of different structural systems for tall buildings that is expected to assist structural engineers and architects to collaboratively select appropriate structural systems for tall buildings.

Use of aerodynamically favorable tapered form in contemporary supertall buildings

“…In addition, hotel, residential, and office uses were considered the basic functions in supertall buildings, while their combinations were considered mixed-use . In this article, considering existing literature (e.g., Taranath, 2016;Ali and Moon, 2018;Fu, 2018;Moon, 2018;Ali and Al-Kodmany, 2022), the following structural system categorization of Ilgın et al (2022b) and Ilgın (2022) were used: (i) shear-frame system (shear trussed frame and shear walled frame); (ii) mega core system; (iii) mega column; (iv) outriggered frame system; (v) tube system (framed-tube including diagrid-framed-tube, trussed-tube, and bundled-tube); and (vi) buttressed core system, while the following structural material classification was used: (i) steel, (ii) reinforced concrete and (iii) composite. Furthermore, the following classification of aerodynamic design considerations (Ilgın and Günel, 2021) was used: (i) major modifications -noticeably changing the overall architectural design -(building orientation, aerodynamic form, plan variation, and aerodynamic top); (ii) minor modifications -not considerably change the overall architectural design -(corner modifications and air pass).…”

“…Figure 7 indicates that outriggered frame systems are mostly used (>70%) in supertall towers in the sample group, followed by tube systems with 20%. The predominance of outrigger frame system can be explained by the fact that this system allows the exterior columns to be widely spaced, thereby minimizing the obstruction created by closely spaced column arrangement, opening the exterior of the building so that architects can articulate the facade freely (Ali and Al-Kodmany, 2022).…”

Interrelations of slenderness ratio and main design criteria in supertall buildings

“…hotel and residential) were considered mixed-use. There is no global consensus on the number of floors or heights of supertall buildings (Ali and Al-Kodmany, 2022). However, in the author's view, taking into account the CTBUH database (CTBUH, 2022), a “supertall building” was considered equal to and taller than a 300 m building, while a “megatall” was a 600 m or higher building.…”

Freeform Supertall Buildings

“…The high preference rate for outriggered frame system may be because it allows the placement of widely spaced exterior columns, thus minimizing the hurdle created by the closely spaced column layout. This gives architects more freedom in designing facades for free forms [30]. Although the diagrid frame-tube system can more accurately identify any free-form tower without distortion thanks to its triangular units, unlike outriggered frame system, its diagonals can be obstructive on the facade.…”