Traditionally, multi-family houses have been constructed using heavy, homogenous materials like concrete and masonry. But as a consequence of the progress of lightweight building systems during the last decades, it has been questioned whether standardized sound insulation evaluation methods still are appropriate.
An extensive measurement template has been applied in a field survey where several vibrational and acoustical parameters were determined in ten Swedish buildings of various constructions. In the same buildings, the occupants were asked to rate the perceived annoyance from a variety of natural sound sources. The highest annoyance score concerned impact sounds, mainly in the buildings with lightweight floors.
Statistical analyses between the measured parameters and the subjective ratings revealed a useful correlation between the rated airborne sound insulation and R0 w þ C50—3150 while the correlation between the rated impact sound insulation and L0 n;w þ CI;50—2500 was weak. The latter correlation was considerably improved when the spectrum adaptation term with an extended frequency range starting from 20 Hz was applied. This suggests that frequencies below 50 Hz should be considered when evaluating impact sound in lightweight buildings.
This paper deals with a certain type of C.L.T. (Cross Laminated Timber) construction, in a residential building in Fristad, Sweden. The objective is to study impact noise transmission, at the lower frequency range (10-200 Hz), where wooden dwellings perform inefficiently, in terms of acoustic quality. The vibrational behavior of lightweight structures and specifically a multilayered floor separating two vertically adjacent bedrooms are investigated. A numerical model of the multilayered test plate, which includes sound insulation and vibration isolation layers, is developed using the Finite Element Method (F.E.M.) in commercial software. The design process, the analysis and improvement of the calculated outcome concerning accuracy and complexity are of interest. In situ vibration measurements were also performed so as to evaluate the structures dynamic behavior in reality and consequently the validity of the modelled results. The whole process from design to evaluation is discussed thoroughly, where uncertainties of the complex F.E.M. model and the approximations of the real structure are analyzed. Numerical comparisons are presented including mechanical mobility and impact noise transmission results. The overall aim is to set up a template of calculations that can be used as a prediction tool in the future by the industry and researchers.
Bosnia and Herzegovina is the most forested country in the Balkan area, and Sweden and Slovenia are two of the most densely forested countries in the European Union. Living habits differ considerably between these three countries, but the use of wood is very similar. This book grew out of the collaboration of three wood scientists with totally different backgrounds who met and discussed their common interest – wood. Based on the different experiences in each country, the idea was to try to find ways to increase the common knowledge base for the use of wood, achieving excellence in timber design research and education; the architect with a deep knowledge of culture based needs, the engineer with experience and knowledge of technological needs, and the practitioner who always has to find the final solution.