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Citicorp Building repairs revisited: answers to a fateful question asked by an undergraduate student forty years ago

Published

Author(s)

Dat Duthinh

Abstract

This paper illustrates the application of the Database-Assisted Design (DAD) method to the wind design of high-rise buildings. The paper uses publicly available wind tunnel data and DAD procedures to compare responses to (i) corner winds and (ii) face winds of a high-rise building of square cross-section supported by a central core column and four mid-side legs. The responses being considered consist of overturning moments, and of demand-to-capacity indexes (DCIs) of selected members, including multi-story chevron braces. The analysis accounts for structural dynamics and second-order load-deformation effects. The results show that corner winds are less demanding than face winds, both globally (overturning moments) and locally (DCIs). The along- and across-wind overturning moments in the corner wind case are about 20 % and 50 % lower, respectively, than their counterparts in the face-wind case. The peak axial forces in the legs (peak refers to absolute value) and the peak DCIs in the mid-side mast columns (continuation of the legs) induced by corner winds are lower by 20 % to 30 % than their counterparts due to face winds. The investigation confirms that the Building Code of the City of New York in effect in the early 1970s can be interpreted as meaning that the design for wind of structures with a square shape in plan may be performed by assuming the wind loads to act normal to a face of the building. The building analyzed in this paper is similar to the Citicorp Building (completed in1977, later renamed Citigroup Center, now called 601 Lexington) and the results of the analyses presented herein suggest that a re-examination of the history of the Citicorp Building design and retrofit may be warranted.
Citation
National Academy of Engineering Online Ethics Center

Keywords

Aerodynamics, Citicorp Building, corner winds, Database-Assisted Design (DAD), Demand-to-Capacity Index (DCI), face winds, high-rise building, mid-side columns, overturning moments.
Created December 2, 2018, Updated August 17, 2020