Search

Kappe+ – evaluation of a traditional construction method as to its performance in today's context Due to their material volume, ceiling systems are one of the biggest challenges in mulit‐storey construction on the way to climate‐friendly building. Here, the traditional masonry cap ceiling proves to be a robust, efficient alternative with innovation potential. Compared to widely used reinforced concrete flat slabs, their production requires only 50 % of the grey energy. To further investigate their application potential, six ceiling systems for office or school use were comparatively examined. Detailed life cycle assessments (LCA) were carried out for these constructions based on pre‐dimensioning. While the reinforced concrete flat ceiling has a Global Warming Potential (GWP) of 136 kgCO2e/m2, the vault ceiling achieves a value of only 64 kgCO2e/m2 in the most favourable case. In addition to assessing the energy input in manufacturing, principles of a circular economy are applied on both the material and construction side. Within a framework of practical experiments, three transformations were carried out on the historical construction: by substituting the steel girders in the system with timber, a new type of timber‐masonry hybrid system is created; with the help of digital manufacturing tools, an economical and contemporary production method is demonstrated; by optimising the bricks used, the raw ceiling is enriched with multifunctional acoustic properties. [ABSTRACT FROM AUTHOR]

Die moderne Architektur strebt nach transparenten Gebäudehüllen und insbesondere nach nachhaltigen und bauphysikalisch adäquaten Glasfassaden. Typischerweise werden Glasfassaden entworfen, um eine Vielzahl von Zielen zu erfüllen, eines davon sind die Anforderungen an den Schallschutz. Eine zuverlässige Abschätzung der Schalldämmeigenschaften beliebiger Glasaufbauten ist aufgrund der Komplexität experimenteller Tests oder numerischer Simulationen zeitaufwendig und kostenintensiv. Daher wird in dieser Arbeit ein maschineller Lern‐Ansatz zur Prädiktion der akustischen Eigenschaften beliebiger Glasaufbauten vorgestellt. SOUNDLAB AI Tool – Machine learning for the determination of the weighted sound Insulation Value. Modern architecture strives for transparent building envelopes and, in particular, for sustainable and physically adequate glass facades. Typically, glass facades are designed to meet a variety of objectives, one of which is to satisfy sound insulation requirements. Reliable estimation of the sound insulation properties of arbitrary glass assemblies is time consuming and costly due to the complexity of experimental tests or numerical simulations. Therefore, this paper presents a machine learning approach for predicting the acoustic properties of various glass setups. [ABSTRACT FROM AUTHOR]

Potential of tree bark for the application as sound absorbing material Tree bark is a highly optimized natural material, which protects a tree from manifold damage at the peripheral layer. Hence, bark has some interesting technological properties, such as a low density and a good biological durability. In the wood‐industry, huge amounts of bark in pieces accrue, which are used to a low extend for high‐value applications. In this investigation, insulation panels from larch bark were produced and their inner structure was evaluated by means of CT. The sound absorption coefficient of panels with varying composition was investigated using impedance measurement and structure‐property relationships were evaluated. It was found that larch insulation panels can be applied as effective sound absorbers for frequencies higher than 500 Hz and that the frequency with the highest sound absorption can be affected changing the particle size of the panels. [ABSTRACT FROM AUTHOR]

Abstract: On the bass ratio in five acoustically outstanding concert halls. Until 1962 all renowned acousticians agreed that one should damp the low frequencies in the reverberation of a room as much as possible. From then on a doctrine was unfortunately spread out that a rise of the bass regime could give music and speech more fullness and warmth and the listener a comfortable envelopment. This imagination still dominates, even in standards, although the leading initiator and supporter of a bass ratio BR > 1 as a quality criterion for acoustics has discarded his own dogma in his book of 2004. In the meantime numerous buildings and reconstructions showed equally subjective evidence that BR ≤ 1 represents an important goal for the desired clarity of music and intelligibility of speech. The objective reason for otherwise unwanted inevitable low‐frequency hum may be found in destructive interference effects of the direct sound of a source with early reflections from the ceiling and walls. The latter should therefore absorb the bass. How well this is achieved may be deduced from the reverberation time in the unoccupied room without heavily upholstered seats, i.e. measured without their absorption always dominating at the irrelevant mid frequencies. In fact, most famous concert halls like Musikvereinssaal in Vienna (of 1877), Concertgebouw in Amsterdam (of 1888), Symphony Hall in Boston (of 1900) und Berliner Philharmonie (of 1963), as well as several other venues with excellent acoustics exhibit a bass ratio BR ≤ 1. The Elbphilharmonie in Hamburg (of 2017) may serve as another example which is highly esteemed by musicians as well as by conscious listeners. [ABSTRACT FROM AUTHOR]

Wave propagation of hydro sound and soil vibrations during the installation of offshore monopile foundations. During the installation of pile foundations for the offshore wind farm Amrumbank West, the new noise mitigation system Hydro Sound Damper (HSD) was used besides the single and double big bubble curtain. To determine the wave propagation and the efficiency of the different noise mitigation methods the Institute of Foundation Engineering and Soil Mechanics of Technische Universität Braunschweig (IGB-TUBS) carried out extensive measuring campaigns. During these campaigns a dense matrix of hydrophones in different water depths and also geophones on the sea bed in distances between 25 and 1500 m from the pile was installed to determine the effects of the different combinations of noise mitigation systems. Additionally the pile itself was instrumented with sensors. Based on these measurements the wave propagation in pile, water and soil is investigated and the efficiency of the noise mitigation measures in different distances to the pile and over the most important frequency range is determined. [ABSTRACT FROM AUTHOR]

In this study, the vibro-acoustic behaviour of centrally damaged honeycomb cored sandwich panels is investigated experimentally. For this purpose, experimental evaluations are completed by the followings: (I) honeycomb sandwich panels with two different core materials and the same skin materials are considered, (II) low-velocity impact measurements with three different projectiles are obtained, (III) vibration and vibro-acoustic tests are performed to present the vibration characteristics of the post-impacted sandwich panels with two different boundary conditions. Effect of core material and projectile geometry on modal and sound characteristics is examined. The results are given in tabular and graphical forms. [ABSTRACT FROM AUTHOR]

Bei der Elbphilharmonie in Hamburg kann man ohne Übertreibung von einem Projekt mit hohem architektonischen Anspruch sprechen. Zahlreiche technische und konstruktiv innovative Lösungen sind Teil der Architektur und ermöglichen erst den neuen, aufgesetzten Gebäudekörper auf dem historischen Kaispeicher mit dem integrierten großen Konzertsaal. Ohne Baustellenzugang oder näherer Projektkenntnisse wird dabei dem Außenstehenden gar nicht ersichtlich sein, in welchen Bereichen der Stahlbau eine tragende Rolle bei diesem Megaprojekt spielt. Dieser Beitrag soll zeigen, wie die herausfordernde Bautechnik gerade in zahlreichen stahlbauspezifischen Konstruktionen im Bereich des Rohbaus in der Ausführung planerisch gelöst und umgesetzt worden sind. Geschildert werden diese Erfahrungen anhand einiger herausragender Beispiele aus Sicht des ausführenden Generalunternehmers HOCHTIEF zusammen mit der zurzeit ausführenden Stahlbaufirma, der Firma spannverbund GmbH. Structural steelwork of the Elbphilharmonie. The Elbphilharmonie in Hamburg without exaggeration can be called a project of high-class architecture. Numerous technical and construction finesses are part of the architecture and only allow the new building structure with its integrated great concert hall to be placed upon the historical warehouse. Without access to the construction site or deeper project knowledge, it will not be obvious for an outsider, in which areas structural steelwork is playing an important part in this challenging project. This paper therefore intends to show, how the technical challenges especially in steelwork specific parts of the structural work were dealt with in planning and execution. These experiences are described from the point of view of the general contractor HOCHTIEF and one of the main steelwork contractors, spannverbund GmbH. [ABSTRACT FROM AUTHOR]

Die von Ernst Mach entwickelte Pfeife ist kein Musikinstrument. Es ist ein Experiment, das die Existenz des Doppler-Effekts ohne großen Aufwand nachweisen konnte. Aufwendigere Experimente hatte zuvor zum Beispiel Trompeter auf vorbeifahrenden Zügen eingesetzt. Machs handlicher Aufbau bestand im Kern aus einer drehbaren Röhre mit einer Pfeife an einem Ende und konnte so den Doppler-Effekt deutlich vernehmbar produzieren. Er schrieb damit Physikgeschichte. [ABSTRACT FROM AUTHOR]