Wind Load Interference Effects on Low and Medium-Rise Residential Building Groups

Abstract

With the ever increasing demand for housing around urban centres and suburbia, and the advent of high-density living, many low-rise buildings are being demolished and replaced with medium and high-rise buildings. Besides, to meet people’s activity needs in the urban planning, architects usually combine the high-rise and low-rise buildings for mixed forms, and such a distribution mode of the building group is bound to lead to a complex flow field. The previous studies showed that the existence of surrounding high-rise buildings in some cases has a significant amplification effect on the wind load of the target low-rise building, which may pose a threat to the structural safety. This project established a series of test models with reference to the terrain conditions, wind speed and building conditions in Auckland, and conducted a systematic study on the interference effect of medium-rise building on low-rise building. To verify the accuracy of the experimental methods in this project, an isolated cubic building under atmospheric boundary layer conditions was simulated by the wind tunnel experiment and CFD respectively. The pressure distribution and aerodynamics characteristics of the building were obtained. The results of average wind pressure based on the RANS model and the LES model were developed and compared with the wind tunnel experiment and previous literature studies. Great accuracy obtained from the comparisons indicated the LES model has capability to provide flow field visualization with reliability. The single variable method was used to study the relationship between interference effect mechanism and spacing ratio (or height ratio) of the target low-rise building by fixing height of the interfering medium-rise building and changing the spacing distance between the two buildings; or fixing the spacing distance, and changing the height of the interfering building. The distribution of wind pressure coefficient and interference factor on the surface of the low-rise building in wind tunnel experiment were roughly consistent with the results of CFD, and the interference effect of the building group was visualized through CFD. Based on the results and findings achieved above, the interference effects of the target low-rise building in four different mixed building groups were further studied by wind tunnel test and CFD. The results showed that the interference effect acting on the target building under different arrangement layouts mainly depended on the extent of obstruction of the upstream building to the incoming flow and the intensity of the feedback airflow from the downstream building.