The distribution of wind pressure on a building envelope is governed by the size and shape of the structure and the turbulence characteristics of the wind. Observation of the mean wind pressures shows that surfaces are divided into pronounced zones of positive and negative pressure. The turbulence gives rise to fluctuating pressure components of appreciable magnitude. This fact changes the prerequisites of the ventilation for a given volume. The pressure in the cavity behind the facade materials depends on the external pressures over the facade.
This paper describes a research project undertaken at the Building Research Station to measure wind pressures at rhe GPO Tower, London. and dynamic strains in the tower shaft. The derelopment of a suitable pressure transducer, which uses strain gauges as sensors, is described together with the. installation at the tower. Some of the problems of strain gauging large civil engineering structures are outlined.
The ventilation performance of a proposed naturally-ventilated court-room was predicted and assessed on a statistical basis with regard to the local meteorological conditions. Summertime ventilation was to be provided via an underfloor duct and controllable vents at roof levels, under the action of wind and buoyancy forces. Wind pressure coefficients expected on the external facade of the building were obtained from wind tunnel measurements on a scale model.
Ventilation produced by fluctuating pressure differences across a building appears to have received little attention . Such fluctuations are produced by gustiness of the wind or turbulence in the flow around a building. An experimantal study has been performed on a laboratory model to investigate unsteady flows through apertures simulating those in the fabric of a building .