Author(s): Schneider Martin, Zeitler Berndt, Ruff Andreas
Masonry is commonly used for the construction of buildings in Germany. Due to energy efficiency the masonry facades are more and more often constructed of two shells sandwiching thermal insulation. The inner shell, typically with a thickness of 150 mm to 240 mm and mass per area of 200 kg/m2 to 480 kg/m2 respectively, ensures the structural safety, whereby the outer shell, typically a brick lining with a thickness of 75 mm to 115 mm and mass per area of 120 kg/m2 to 220 kg/m2 respectively, ensures the environmental protection (e.g. from wind and rain). The cavity is typically filled with 120 mm to 250 mm of thermal insulation material, such as mineral wool or polystyrene.\nDue to wind and seismic loads the outer shell is connected to the structural inner shell by 5 to 10 tie bars per square meters, typically 4 mm in diameter. Further anchors are located above openings (e.g. windows and doors) where the outer shell is fastened to brackets. The quantity and location of the anchors changes the dynamic coupling between the two shells and could diminish the sound insulation of the wall.\nIn this paper the sound insulation and vibration patterns of such a wall is investigated in the laboratory. Besides standard airborne measurements, a modal analysis of the wall was carried out to visualize the vibration pattern of the wall in the low frequency range. These results are compared with FEM-calculations, in which different types and quantity of the connections between the walls were investigated. The presented results are the first of a series of investigations planned with heavy masonry inner shells and various outer shell types.
Name: Mr Martin Schneider