Measurements of vibration reduction indices path over junctions AAC/CSU

Abstract

AbstractIf the sound reduction index of a construction between rooms is to be calculated according to the European standard EN 12354‐1:2017‐11 “Airborne sound insulation between rooms,” the so‐called vibration reduction index is an important input variable, which can be determined both simplified according to Annex E of the standard or via measurements on the basis of EN ISO 10848‐1:2018‐02 and EN ISO 10848‐4:2018‐02. The vibration reduction index factor kij characterizes the transmission of a structure‐borne sound power and results from the direction‐averaged junction velocity level difference at the joint. The length and the equivalent absorption area of the components involved at the joint are standardized and thus made formally applicable for different construction situations. According to EN 12354‐1:2017‐11, in the simplified procedure, the vibration reduction index factor kij, which is determined mathematically via the logarithmic mass ratio of the components or via measurements, is included in the calculation of the flanking sound insulation as follows: urn:x-wiley:25097075:media:cepa2227:cepa2227-math-0001To date, only a few measurements have been carried out in sound laboratories to determine the size of kij. In general, the simplified determination of kij according to Annex E of EN 12354:2017‐11 is used. On behalf of Xella Germany, the Xella Technologie‐ und Forschungsgesellschaft measured the values for kij at a total of 8 joints (so‐called T‐joints). These joints are common component connections between AAC and CSU and occur predominantly at the connection between the load‐bearing exterior wall and a load‐bearing CSU interior wall.The joint insulation dimensions determined by measurement at the T‐joints of CSU and AAC masonry are in part significantly higher than the calculated values determined from the area‐related masses. For the transmission path along the flank (Ff along the walls), the values determined are only slightly above the predicted values at approx. 1–2 dB. On the transmission path from the separating wall to the flank (Df or Fd), the values determined by measurement are in some cases significantly higher (by up to 6 dB) than the values determined by calculation.The flank insulation of AAC is therefore usually underestimated with the simplified method for determining kij.