TY - JOUR A1 - Miccoli, Lorenzo A1 - Perrone, C. A1 - Fontana, Patrick A1 - Müller, Urs A1 - Ziegert, C. T1 - Charakterisierung und Modellierung der mechanischen Eigenschaften von Lehmsteinmauerwerk / Mechanical characterization and modelling of earth block masonry N2 - Das Wissen über die Materialeigenschaften und die Versagensmechanismen bei Lehmbaustoffen ist begrenzt und lückenhaft. Im Rahmen des EU-Projekts NIKER (www.niker.eu) wurden deshalb die mechanischen Eigenschaften von Bauteilen aus Lehm unter statischer Druck- und Schubbeanspruchung bestimmt. Ziel der Untersuchungen war es, grundlegende Daten zum Verformungs- und Versagensverhalten von Lehmbauteilen zu erhalten und dieses mit einem numerischen Modell zu beschreiben. Die Versuchsergebnisse belegten das spröde Verhalten von Lehmsteinmauerwerk bei uniaxialer Druckbelastung und zeigten, dass das Versagen von Lehmsteinmauerwerk infolge Schubbelastung nach Erstrissbildung in Mörtelfugen und Lehmsteinen durch Gleiten der Lehmsteine entlang der Mörtelfugen erfolgt. Die numerische Makromodellierung erbrachte zwar befriedigende Resultate hinsichtlich des Spannungs-Dehnungs-Verhaltens, jedoch konnte bei der simulierten Rissbildung keine Übereinstimmung mit den in den Versuchen beobachteten Rissbildern erzielt werden. Bei Lehmsteinmauerwerk ist also eine wesentlich aufwendigere Mikromodellierung notwendig, um das Versagensverhalten korrekt beschreiben zu können.-------------------------------------------------------------------------------------------------------------- Knowledge of the material properties and failure mechanisms of earthen materials is limited and scattered. Within the framework of the NIKER project (www.niker.eu) funded by EC, the mechanical properties of earthen material elements were therefore determined under static compression and shear loads. The aim was to obtain fundamental data on deformation behaviour and failure mechanisms of earthen material structural elements and to describe them by means of a numerical model. The test results confirmed the brittle behaviour of earth block masonry under monoaxial compressive load and showed that the failure of earth block masonry under shear load occurs by sliding of the earth blocks along the mortar joints after initial cracking in mortar joints and earth block. Numerical macro modelling showed satisfying results with regard to stress-strain behaviour, but the simulated crack pattern was not consistent with experimental observations. In the case of earth block masonry, it is thus necessary to use micro modelling approaches in order to correctly predict the failure process at local level. KW - Lehmstein Mauerwerk KW - Druckversuche KW - Schubversuche KW - F.E.M. Modellierung PY - 2012 U6 - https://doi.org/10.1002/dama.201200555 SN - 1432-3427 SN - 1437-1022 N1 - Sprachen: Deutsch/Englisch - Languages: German/English VL - 16 IS - 6 SP - 279 EP - 292 PB - Ernst CY - Berlin AN - OPUS4-27589 LA - mul AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, Urs A1 - Ziegert, C. A1 - Kaiser, C. A1 - Röhlen, U. T1 - Eigenschaften industrieller Lehmbauprodukte für den Mauerwerksbau und Verhalten von Lehmsteinmauerwerk N2 - Der Beitrag gibt einen Überblick über die Eigenschaften industriell hergestellter Bauprodukte aus Lehm für den Mauerwerksbau. Die Qualität der industriellen Fertigung dieser Produktgruppe hat inzwischen einen Stand erreicht, der vergleichbar mit dem anderer Bauprodukte ist. Lehm-Putzmörtel gibt es als Universalputze für ein- oder mehrlagige Anwendung oder in Form von Unter-, Ober- oder Feinputzen. Lehmsteine werden in verschiedenen Größen und mit Lochung angeboten. Die mechanischen Eigenschaften verschiedener Lehmsteinsorten sind geprägt durch Druckfestigkeiten bis 11 N/mm2, mit üblichen Werten bei 2 bis 5 N/mm2. Ein kritischer Punkt ist die Abhängigkeit der Festigkeitseigenschaften der Lehmsteine von der Materialfeuchte. Die vorliegenden Untersuchungen haben jedoch gezeigt, dass in einem Luftfeuchtebereich von 40 bis 70 % RLF die Druckfestigkeit von Lehmsteinen verhältnismäßig konstant ist. Mauerwerk, errichtet mit Lehmsteinen und Lehm-Mauermörtel, zeigt ähnliche Druckfestigkeiten und E-Module wie Mauerwerk, das mit Porenbetonsteinen errichtet wurde. Infolge einer geringeren Haftscherfestigkeit zwischen Lehmmörtel und Lehmstein ist die Schubfestigkeit von Lehmsteinmauerwerk vergleichsweise niedrig.------------------------------------------------------------------------------------------------------------------------------------- Properties of industrially produced earthen building products for masonry and behaviour of earth block masonry. The contribution gives an overview of the properties of industrially produced earthen building products for masonry. In the meantime the quality of the industrial production of this group of building materials reached a level similar to that of other products for construction. Earth plasters exist as plasters for universal, one or multi layer applications or as lower, upper or finish plasters. Earth blocks are provided in different sizes and with different perforations. The mechanical properties of different earth block types are signified by compressive strength of up to 11 N/mm2 but are typically in a range between 2 and 5 N/mm2. A critical point is the correlation of the strength of earthen materials with their moisture content. Results from earth blocks showed that in a relative humidity window between 40 and 70 % rh the compressive strength of earth blocks is fairly constant. Masonry made from earth block and earth mortar exhibited compressive strength and elastic modules similar to masonry made with aerated autoclaved concrete blocks. The shear strength of earth block masonry, however, is fairly low, due to the weak bond between earth block and earth mortar. PY - 2012 U6 - https://doi.org/10.1002/dama.201200527 SN - 1432-3427 SN - 1437-1022 VL - 16 IS - 1 SP - 17 EP - 28 PB - Ernst CY - Berlin AN - OPUS4-27744 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, U. A1 - Miccoli, Lorenzo A1 - Perrone, C. A1 - Ziegert, C. T1 - Vergleich und Modellierung der mechanischen Eigenschaften von Bauteilen aus Lehmsteinmauerwerk, Wellerlehm und Stampflehm T2 - Lehm 2012 - 6. Internationale Fachtagung für Lehmbau CY - Weimar, Germany DA - 2012-10-05 KW - Stampflehm KW - Lehmstein KW - Mauerwerk KW - Wellerlehm KW - Mechanische Eigenschaften PY - 2012 SN - 978-3-00-039649-6 IS - Session C SP - 320 EP - 331 AN - OPUS4-26936 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Miccoli, Lorenzo A1 - Müller, Urs A1 - Perrone, C. A1 - Ziegert, C. T1 - Earth block masonry, rammed earth and cob: earthen components from different construction techniques and their structural performance N2 - Both in developed and developing countries, modern building materials tend to be preferred to traditional earthen construction. Reasons include low durability, inadequate performance under seismic loading and, in developing countries, a wish to replace what is perceived as 'poor' with what is perceived as 'rich'. In an age when building permissions and construction standards are a must, particularly in seismic areas, even when an owner is willing to build in earth, construction approval needs to be granted: we rely on values and standards to build, but the necessary data on material properties and structural performance of earthen building techniques is scarce if compared to the abundance of data for other materials (clay brick masonry, concrete, steel) available to the engineer. At the same time, traditional builders' skills, knowledge and confidence in earthen building techniques are decreasing if not disappearing. A wallette testing campaign was thus carried out with the aim of filling this knowledge gap. Prior to the wallette campaign, material properties, including composition and physical-mechanical parameters, were determined. Compression and diagonal compression (shear) tests were then performed, and a basic analysis of the mechanical behaviour of structural elements built in cob is provided in relation to earth block (adobe) masonry and rammed earth elements. Cob, shown to have low compressive resistance, has a relatively ductile post-peak behaviour if compared to earth block masonry specimens which, as expected, show a marked brittle behaviour. In terms of shear strength, cob performs relatively well in view of its low compressive strength. The study is part of our work within the framework of the ongoing project NIKER funded by the European Commission dealing with improving the structural performance of Cultural Heritage assets in order to limit earthquake hazards. T2 - Terra 2012 - 11th International conference on the study and conservation of earthen architecture heritage CY - Lima, Peru DA - 2012-04-22 KW - Earth block KW - Rammed earth KW - Cob KW - Mechanical properties KW - Earthen architecture KW - Earth block masonry PY - 2012 SN - 978-9972-2885-5-5 IS - Theme 6 - t6_066 SP - 1 EP - 10 AN - OPUS4-30380 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pavlovic, Mato A1 - Ronneteg, U. A1 - Müller, Christina A1 - Ewert, Uwe A1 - Boller, C. T1 - Safe product design - the role of the NDE reliability analysis N2 - When pushed to the limits of their detection capability, NDE systems do not produce consistent hit/miss indications. Their capability of detecting small defects is therefore expressed in terms of POD. An adequate NDE system is required to ensure the structural integrity. In conventional signal response analysis, the POD is expressed as a function of the defect size, and its adequacy for the inspection task is tested against the maximum allowable defect size which will not undermine the structural integrity. Analyses of modern structures show that other parameters, beside the defect size, can both significantly influence the POD and determine the severity of the defect for the structure. Within the multi-parameter reliability analysis, the POD is expressed as a function of those influencing parameters. When determining the adequacy of the NDE system, the capability of detecting a defect has to be expressed and tested against the critical value of exactly that parameter that determines defects severity for the structure. Failing to do so can lead to a rejection of the healthy, or acceptance of the bad part. The principle is demonstrated on the example of the Transmit-Receive Longitudinal (TRL) ultrasonic inspection of the iron cast component for semi-elliptical surface defects. T2 - 18th WCNDT - World conference on nondestructive testing CY - Durban, South Africa DA - 2012-04-16 KW - Reliability KW - Probability of detection (POD) KW - Multi-parameter KW - Ultrasonics KW - Transmit receive longitudinal (TRL) PY - 2012 SN - 978-0-620-52872-6 SP - 1 EP - 9 (Paper 310) AN - OPUS4-27581 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weise, Frank A1 - Maier, Bärbel A1 - Alonso, M. T. A1 - Müller, C. T1 - Analyse des Verhaltens von Gesteinskörnungen im Beton bei Frosttauwechselbeanspruchung T2 - 18. Ibausil - Internationale Baustofftagung CY - Weimar, Germany DA - 2012-09-12 PY - 2012 SN - 978-3-00-034075-8 VL - 2 IS - 3.07 SP - 2-0453- 2-0467 AN - OPUS4-26546 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -