Characteristics of internal pressures in buildings with a dominant opening

A building with a dominant windward wall opening will produce large internal pressures during a severe wind event and is a structural design criterion. Internal pressures were measured using a boundary layer wind tunnel for a series of windward dominant opening sizes, internal volume sizes and background building porosities. Internal pressures were also estimated using numerical simulations of the governing equation incorporating background porosity. The background porosity was represented as a single lumped porous opening. Results were presented in terms of a non-dimensional dominant opening size to internal volume parameter, S* and the lumped background porosity area to dominant opening area parameter, Φ₆.\ud \ud The measured internal pressure results were compared with measured external pressures at the dominant opening. For the sealed building scenarios (no background porosity) but with a dominant opening, the mean internal pressure was equal to the mean external pressure, and the internal pressure fluctuations (standard deviation) and peaks were dependent on the size of the dominant opening and size of the internal volume. For porous building scenarios, the internal pressure mean, standard deviation and peaks were attenuated with varying levels of increasing porosity.\ud \ud The internal pressure numerical simulations were matched with the experimental results by varying the inertial coefficient of the dominant opening and discharge coefficients for the dominant opening and lumped porous opening. The lumped porous opening discharge coefficients varied with the dominant opening discharge coefficients. The dominant opening inertial and discharge coefficients varied with the sizes of dominant opening area and internal volume. The range of dominant opening inertial coefficients was larger than the theoretical value of 0.89. The range of discharge coefficients for the dominant opening was less than the steady flow value of 0.61. Further experiments on the flow through dominant openings were conducted using a pressure loading actuator. The results show that when the flow through an opening reverses (i.e.) changes direction, the discharge coefficient is significantly reduced