Development of a wind tunnel model compared with results of method of initial parameters and BS6399 models for dynamic analysis of multi-storey building subjected to aerodynamic loadings

Abstract

The research investigated the development of a wind tunnel model compared with results of method of initial parameters and BS6399 models for dynamic analysis of a multi-storey building subjected to aerodynamic loadings. The dimensional analysis which based its concept on the law of motion and energy conservation was used as wind tunnel experimental data assessment tool, for the determination of the aerodynamic loadings for a multi-storey building. Although, this problem was earlier solved using dimensional analysis with different approaches by many Scholars but such solutions did not include an important quantity; the influence of the structure’s deflection (δ) and foundation infinitesimal rotation. The study observed that, the non-stationary component is also dependent of the stationary component of the aero-dynamic force. It also explained how the product of the Strouhal number (St) and model relative displacement (Lo number), is equal to the Bernoulli universal constant, 0.5. Tests on most important parameters capable of influencing the assessment and design of multi-storey buildings with varying height-breadth ratio, basic wind speeds, relative displacement and aspect ratio increased with logarithmic laws as a function of model height; but the reduced frequency, decreased with polynomial and power laws respectively. It was therefore concluded that, aero-elastic damping property of the structure is influenced by the Lo number and in particular, λ. Finally, the cumulative base moment from the mathematical (method of initial parameters) model is 2.108% higher than the physical model result and the results from the BS6399 model was less by 1.732%. In general, a difference varying between ±2.1% is within acceptable level of deviation for most conventional engineering and scientific design results. Key words: Dimensional analysis, Strouhal number, Bernoulli universal constant, wind tunnels, initial parameters, BS6399, multi-storey buildings, aero-elastic damping, aero-dynamics loadings.