Equivalent static wind loads vs. database-assisted design of tall buildings: An assessment

Abstract

Recent developments in pressure measurement technology, and unprecedented “big data” capabilities, have enabled the development of Database-Assisted Design (DAD), a powerful innovative approach to the design of tall buildings for wind. DAD eliminates unwieldy back-and-forth interactions between the wind and the structural engineer, needed in traditional practices if iterative designs are performed. Some structural engineers have shown interest in an alternative approach that uses equivalent static wind loads (ESWLs) in lieu of DAD. Such an approach is warranted if ESWLs induce in structural members demand-to-capacity indexes (DCIs) approximately equal to their peak counterparts obtained by DAD. This paper presents and assesses a simple procedure for calculating such ESWLs. The procedure uses an effective multiple points-in-time (MPIT) method for estimating combined peak wind effects, and accounts for wind directionality. A case study is presented that uses both the ESWL and DAD procedures, with the latter providing the requisite benchmark results. DCIs obtained from ESWLs based on the use of ten points-in-time (corresponding to 60 wind loading cases) were significantly closer to the benchmark DAD values than their counterparts based on the use of, e.g., four points-in-time (corresponding to 24 wind loading cases). For the building considered in this case study, ESWL-based design DCIs approximated to within approximately 3% the DCIs yielded by DAD. The approximation was found to be poorer for cases in which a single unfavorable wind direction is strongly dominant. The ESWL procedure is not applicable in its present form to structures with complex shapes. In all cases, the DAD procedure is the safest and most risk-consistent design option.