Wind load analysis of a high-rise building by computational fluid dynamics

Abstract

As new buildings become taller due to limited land area, often irregular in shapes for esthetics and some design constraints, wind load formula provided in design codes/standards cannot be applied because of the limitations. Wind tunnel test (WTT) is thus the suggested approach to obtain appropriate wind load for the design of such buildings. However, WTT is costly and time-consuming as it often requires much preparation of the small-scale model of the target building, instrumentation, and numerous realistic blocks of surrounding buildings (SBs). In this study, the CFD's accuracy will be evaluated by comparing its results to WTT by a wind loads analysis of a 150m-tall irregular-shaped building in Bangkok with consideration of the influence of 400 m radius of the neighboring area. CFD was implemented in ANSYS Fluent for the conditions as close as possible to the WTT setup. Two most effective CFD approaches: (1) k-ω-SST (shear stress transport) turbulence model (TB) and (2) Large Eddy Simulation (LES) were used in the simulation as two alternatives and evaluated to identify the more promising method. Results showed that LES provides slightly better accuracy, but the k-ω-SST TB still provides reasonably acceptable accuracy compared to WTT. However, k-ω-SST TB requires significantly less computational time. Besides, the comparison of CFD results from the case without and with SBs reveals that SBs play an essential role in turbulence development at low elevation and significantly influence the target building's wind pressure. Finally, CFD's wind load analysis applications were summarized to show the connection between CFD and building codes/standards in the wind load evaluation.