Estimation of Wind-Induced Pressures on a Low-Rise Building Using Quasi-Steady Theory

Chieh-Hsun Wu,Gregory A Kopp

doi:10.3389/fbuil.2016.00005

Abstract

A quasi-steady (QS) model that includes both the instantaneous wind azimuth and elevation angle is applied and extended to relate the instantaneous wind speeds and roof pressures for a typical low-rise building. The construction and validation of the QS vector model were done through the synchronized measurements of wind speed and building surface pressures on 1/50-scale model of the TTU-WERFL Building in a boundary layer wind tunnel. The results show that the QS predicted pressures are more highly correlated to the measurements when the elevation angle is included. A statistical method for estimating the probability density functions, based on the assumptions from the QS model, is derived and validated. This method relates the probability density function (pdf) of building surface pressures to the joint pdf of wind speed, azimuth angle and elevation angle.

Highlights

IntroductionIn many wind tunnel measurements, building surface pressures, Δp, are related to the mean velocity, V, through standard (or typical) pressure coefficients, Cp,t, Δp = ρV 2Cp,t (1)
In many wind tunnel measurements, building surface pressures, Δp, are related to the mean velocity, V, through standard pressure coefficients, Cp,t, Δp = ρV 2Cp,t (1)where ρ denotes the air density and Δp denotes the difference between the surface pressure, p, and ambient static pressure, p0, i.e., Δp = p − p0
The quasi-steady (QS) theory assumes that the instantaneous surface pressures are a multiplication of the instantaneous dynamic pressure, 0.5ρV2, and the instantaneous pressure coefficient, Cp,inst, i.e., Δp where V is the magnitude of velocity, which is formed by its components in longitudinal, u, transverse, v, and vertical, w, directions, i.e., V2 = u2 + v2 + w2 (3)

Summary

Introduction

In many wind tunnel measurements, building surface pressures, Δp, are related to the mean velocity, V, through standard (or typical) pressure coefficients, Cp,t, Δp = ρV 2Cp,t (1). Pressure coefficients are measured directly with the mean velocity obtained via a Pitot-static tube placed in a low turbulence region away from the building model (e.g., Ho et al, 2005). This allows straightforward calibration for accurate measurements, but implies that pressure coefficients must be re-referenced using velocities measured separately (e.g., Ho et al, 2005). The quasi-steady (QS) theory assumes that the instantaneous surface pressures are a multiplication of the instantaneous dynamic pressure, 0.5ρV2, and the instantaneous pressure coefficient, Cp,inst, i.e., ρV2 Cp,inst (2)

Methods

Results

Discussion

Conclusion