RESPONCE VINDICATION OF EFFECTS OF CORNER CONFIGURATION AND INTERFERENCE ON TALL BUILDINGS UNDER WIND LOADS USING CFD MODELLING

Abstract

This study explores a recent application of the computational fluid dynamics technique “CFD” for wind analysis and its comparisons with the conventional wind tunnel experimentations. This study is centered on the wind response of square and corner cut-shaped building models and its optimization caused by the variation of the wind incidence angle. Extensive rigid model experiments of two building models of length scale 1:100 have been performed in the boundary layer wind tunnel. The numerical analysis has been carried out with the standard k-ε turbulence model to evaluate the force coefficients, base moments, power spectra, external surface pressure coefficients, and flow field characteristics of the models with variable wind angles of incidence. The comparisons between experimental results and CFD analysis suggest the computational approach’s viability in wind analysis of tall structures efficiently and accurately. A case study of aerodynamic mitigation by corner cut suggests minor modification techniques performance, efficiency, and limitations. Wind induced interference plays a vital role in the design of tall structures. However, the complex features of structure design and shape require a detailed wind tunnel/CFD (Computational Fluid Dynamics) study as codal provisions don’t suffice for such scattered parameters. iv The current study focuses on the effects of height ratio, orientation, and blockage configuration of interfering structure on interference effects. Interference factor (IF), transient pressure, and force spectra are used to account for the interference effects at major probe points to understand the dynamic wind response. To study these effects among complex arrangements, a numerical simulation for a CFD analysis on a corner configured principal building model and a single upstream interfering building model having identical geometry has been performed. The configuration included six kinds of heights ratio (Hr=Hprincipal/Hinterfering). Furthermore, force coefficients, base moments, and external surface pressure coefficients both in the along and across wind direction are determined and listed for wind incidence angle of attack of 0° to 90° at an interval of 15°. Interference effects among full, half, and no blockage conditions were investigated. The data is presented in terms of the interference factor relating wind load responses of the isolated principal building to interference configuration. The results indicate that in close proximity of structure, the shielding effect suppresses the interference effects on the principal building, but across wind responses have been investigated in close vicinity configurations too. This study also suggests the interfering model’s orientation contributes to great measures to the wind response under interference.