Antonino Di Bella

Analysis of acoustic behavior of bare CLT floors for the evaluation of impact sound insulation improvement

Estimation of the impact sound insulation of horizontal partitions, evaluated from the performance of basic components according to EN 12354-2, does not provide satisfactory results when applied to floors made of Cross-Laminated Timber (CLT) elements. One of the most interesting reasons for this limited match between predicted and measured impact noise values is the difficulty of correlating the reduction of the impact sound pressure level of the floor covering, measured in a laboratory on a concrete slab, with the actual behavior on a bare CLT floor. Reported here are the results of laboratory evaluations, independently carried out by various researchers on similar CLT structures. The purpose of this study is to identify the empirical spectrum of the normalized impact sound pressure level of a reference floor made according to CLT technology, to provide a simple and useful tool for estimating the noise insulation performances of this type of building element.

Prediction of noise of moored ships

The European Directive 2002/49/CE suggests to map noise in harbor areas with methods mainly used for industrial noise, in accordance with ISO standards. Nevertheless, in many cases, these methods do not seem suitable to describe the effects of noise due to moored cruise ships. For noise measurements of ships, it is possible to refer to ISO 2922 standard, but it results ineffective for the estimation of noise levels at distances bigger than 25 m from the sound source and to obtain reliable information about sound power level of big vessels. The aim of this study, performed by the University of Padova on behalf of Venice Port Authority, is to improve a procedure for predicting noise of moored ships in the harbor area by the means of measures and reverse analysis with numerical models.

In Situ Characterization and Noise Mapping of Ships Moored in the Port of Venice

The acoustical characterization and the mapping of noise emitted from ships were carried out on behalf of the Venice Port Authorithy in the frame of the European Project NoMEPorts (Noise Management in European Ports). According to the Directive 2002/49/CE (END), different noise sources (like roads, railways, aircraft, industrial sites, ports) have to be considered and mapped separately; so, in the first step, the acoustical characterization of ships is required. Annex IV of the Directive, in particular, establishes that the strategic noise maps for agglomerations shall put a special emphasis on the noise emitted by, inter alia, industrial activities, including ports. Three kinds of ships were investigated, using the Italian technical standards UNI 10855 and UNI 11143: 1. inland navigation ships (along wharves); 2. ferries (along wharves and when maneuvering); 3. cruises (along wharves and when maneuvering). As for the maneuvering, it could be said that a supplementary noise indicator is needed, as the END...

Improvement of acoustic and thermal performances of façades on retrofit buildings

Deep renovation of existing buildings represents an important strategy to go beyond the standard energy retrofit (as the increasing of thermal insulation of building envelope) and to provide more benefits to residents considering non-energetic aspects, like the improvement of architectural quality of building and of indoor life quality. In this context, facades additional elements (balconies, solar greenhouses, etc.) can be effective solutions in order to increase thermal and acoustic performances as well as providing a more living space to the outside. This paper analyzes and compares different technical construction systems for facade improvement in order to define robust solutions correlated both to outdoor climate context (to increase energy performances towards nearly Zero Energy Buildings) and to outdoor noise for a better acoustic sound insulation. A case study is presented, and dynamic energy simulations, performed on a building made with materials and construction technology widespread in Italy ...

Optimization of Mechanical and Acoustic Performance of Timber Floors

In the paper, the results of an experimental study aimed at evaluating the mutual influence among the intervention techniques normally employed to improve separately the acoustic or the mechanical performance of timber floors are provided. The superimposition of planks having different thickness and arrangement or connections is usually considered to improve the in-plane stiffness of floors, especially in case of interventions on existing buildings in seismic zone, to take into account, if possible, also preservation criteria. On the other hand, the improvement of acoustic comfort is addressed to the use of specific noise-abating materials, like insulating boards (OSB) or sheathings, whose contribution, in terms of mechanical stiffness/strength is often neglected. This work proposes a combined interpretation of the two abovementioned requirements, through the characterization of the main parameters governing the involved physical and mechanical phenomena. The first results obtained on simple unidirectional full-scale specimens of floors are presented; seven combinations among various solution of boards and noise-abating materials are compared, first from a structural and subsequently acoustic point of view. The results allow identifying the solution, which is able to optimize at best both the mechanical and acoustic requirements, to be proposed for the intervention on existing timber floors.

Multi‐purpose apparatus for evaluation of noise transmitted through air ducts

The noise generated in HVAC systems by fans or air turbulence is propagated along ducts and, through duct walls, can be irradiated in rooms; moreover duct lines can easily transmit the sound produced in noisy environments from one room to another, vanishing the sound insulation of walls which they are passing through. The knowledge of sound insulating properties of duct walls is fundamental for a good system design, including unitary attenuators and active noise control devices. In this work a multi‐purpose apparatus for evaluation of noise transmitted through air ducts in a reverberant room is presented. This apparatus allows one to measure, with the same equipment, the sound power level emitted from a short length ducts specimen in a reverberant room, as well as linear sound attenuation and break‐in and break‐out transmission loss. A further application of the same apparatus is the measurement of sound insulation and normal incidence impedance of small plane elements of isotropic or composite materials.