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Tuulen painevaikutusten vaimentaminen rakenteellisesti

Authors
  • Karvonen, Marja-Liisa
  • Virtanen, Markku
Publication Date
1988
Source
VTT Publications Register
Keywords
License
Unknown

Abstract

Structural methods for damping of the wind effects on the pressure conditions of small houses were studied both by computer simulations and field measurements. The effect of wind pressure variation has been, so far, the most important disturbance of the controllability of supply air intake in mechanical exhaust ventilation system a which was considered in this study. The airflow balance calculations were carried out by using a steady-state network model based on electric network analogy. The experimental study was done in test houses. One of the basic ideas is that the supply air is taken in through a ventilating air space. If the lower edge of the ventilating air space is closed or strongly throttled, the damping effect is essentially improved. If both the upper and lower edge is closed, the damping effect of the structure depends on the flow characteristies of the ventilating air space and the airtightness of the outer surface. The latter kind of structure is not realizable in practice for wind pressure damping purposes, because the tighter the outer surface is, the better is the damping effect. On the other hand, by improving the airtightness of the outer surface the pressure difference between outside and inside air is increased, which is not desirable. A well functioning wind pressure damping system can be obtained with relatively few changes in the conventional wall structure. It is insisted that the building is supplied with an attic space. In addition, the lower edge of the ventilating air space should be closed and the connection between ventilating air space and attic space should be nearly frictionless. Also, the flow resistances of the eaves structure should be ignorable. This kind of structure can rather easily be realized in practice, because the wind pressure damping effect is not very sensible for the air tightness of the outer surface and for the flow characteristics of the ventilating air space. There is good agreement between the calculated and measured results.

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