Internal pressure in a building with multiple dominant openings in a single wall: Comparison with the single opening situation

Abstract

A generalized theoretical model of internal pressure dynamics in a building with multiple openings on a single wall with highly correlated external pressure is developed. Analytical and wind tunnel studies on a model building for the case of two closely spaced dominant openings in a single wall showed that internal pressure in such configurations increase with increase in the ratio of opening sizes, and become almost equal, but slightly less than that for the most critical single opening configuration under normal onset flow, when the combined area of the two openings become double the critical single opening size. For wind angles within ±45-70°, the Root Mean Square (RMS) and the peak ratio internal pressure coefficients for the two-opening configuration of area ratio unity are found to be much higher than the most critical single opening configuration due to the "tangential flow" excitation through the openings provided by the two near-simultaneous oblique jet flows. For the sidewall two-opening configurations corresponding to wind angles 100-140°, the RMS internal pressure fluctuations are found to be somewhat suppressed due to flow short-circuiting through the two openings resulting from flow separation and external pressure gradient. The internal pressure provisions of AS/NZS 1170.2.2011 for internal pressure design in buildings with potential multiple openings on a single wall are found to be adequate for most wind angles.