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By means of a small-scale truss bridge, the ability of the Measurement- and Model-based Structural Analysis to detect and localize damage was examined. Although there was no noteworthy difficulty in detecting damage, it turned out that damage localization responds sensitively to systematic influences, i.e. non-modelled properties of the mechanical model. Therefore, another experiment is being conducted to re-examine the Measurement- and Model-based Structural Analysis. For this purpose, the bending test is carried out as it has been already theoretically respectively numerically discussed. In this attempt, the systematic influences such as residual stress are kept as low as possible.
By means of a small-scale truss bridge, the ability of the Measurement- and Model-based Structural Analysis to detect and localise damage was examined in. Although there was no noteworthy difficulty in detecting damage, it turned out that damage localisation responds sensitively to systematic influences, i.e. non-modelled properties of the mechanical model. Therefore, another experiment is being conducted to re-examine the Measurement- and Model-based Structural Analysis. For this purpose, the bending test is carried out as it has been already theoretically respectively numerically discussed in. In this attempt, the systematic influences such as residual stress are kept as low as possible.
The Measurement- and Model-based Structural Analysis (MeMoS) integrates a finite element model into least squares adjustment and thus allows to evaluate a mechanical model and measurements in a combined analysis. To examine the capability to detect and localise damage using this integrated analysis MeMoS, a small-scale truss bridge made of aluminium profiles is built as a test specimen for this purpose.
To examine the capability to detect and localise damage using the Measurement- and Model-based Structural Analysis (MeMoS), a small-scale truss bridge (1520 mm × 720 mm × 720 mm) made of aluminium profiles is built as a test specimen for this purpose. The truss frame of the test bridge is made of aluminium profiles with a sophisticated design of the cross-sectional area. In comparison, with solid profiles, only a fraction of the material is needed to produce the profiles, while their bending resistance decreases slightly. The profiles are built into a truss frame by connecting them by means of fastening sets made of steel. The bridge model is mounted on four steel bearings which each of them consist of a cylinder arranged between two plates. Fixed bearings are made by holding onto one end of the bridge. The bridge is subjected by an external load by placing a heavy object beneath it. At the same time, measurements can be conducted below the bridge. Therefore, the bridge specimen is elevated by attaching it on a pedestal with four columns. Damages can be induced by loosening the fastening pieces.
The use of open GIS standards offers a broad variety of potential, particularly in the field of data exchange, data storage, and interoperability. GML and CityGML are excellent examples for the ontological description of real world objects by means of an open standard whereas SensorML serves to describe measurements, sensors and measuring platforms. The use of such standards offers not only the possibility of using a common standardised language, but also the use of open service standards. The combination of spatial data and sensor standards in services and service-oriented architectures goes far beyond previous existing solutions on the market and provides a novel platform for monitoring structures. That in fact is far more than a simple data storage model. The methods and models presented in this contribution allow a direct integration of sensor data and its provision through an open standard language. In this case, all the intermediate steps at any time through an open service interface are addressed and may be made available and provided to different actors and stakeholders participating in a construction scenario. The great potential and the added value of such an information system is the permanent availability of measurement and object data and an associated integrated analysis of sensor data in combination with a finite element model (FEM). The automatic derivation of a finite element model from the 3D structure model, the visualisation of FEM, the provision of raw (measurement) data and sensor information for each time of measurement transform the platform into a universal tool in the field of structural monitoring. This contribution introduces the individual components, the standards used and the interaction between the components to an overall system.
Many engineering structures are made of composite materials or metal foam. To simulate the deformational behaviour of these structures often requires a high number of discretisation elements. This in turn yields a very large system of linear equations that are extremely time and memory consuming or practically impossible to solve. It is therefore desirable to find an approach to overcome this obstacle.
Many engineering structures are nowadays made of composite materials or metal foam. These modern engineering materials contain very complex inner geometry. To simulate the deformational behaviour of these structures often requires a high number of discretisation elements. This in turn yields a very large system of linear equations that are extremely time and memory consuming or practically impossible to solve. It is therefore desirable to find an approach to overcome this obstacle. In this paper a numerical method is proposed to find an approximate substitute model for geometrical complex structures.
One major ambition in Structural Health Monitoring (SHM) is to develop the ability to detect, identify and localize damage as well as to predict the lifespan of civil structures. This would allow well-informed decision on whether to repair or to demolish these structures. We want to focus on the issues of detection and localisation of damage caused by material degradation within a slender beam - a structure that is often used as a construction carrier.
Integration der Finite-Elemente-Methode in die Ausgleichsrechnung zur Parameteridentifikation
(2014)
Die Strukturüberwachung von Ingenieurbauwerken beruht heutzutage auf einer Auswertung räumlich und zeitlich verteilter hybrider Messungen, die z. B. mittels Tachymeter, Neigungssensoren, faseroptischen Sensoren (FOS), Dehnmessstreifen (DMS), GPS etc. erfasst werden. Für eine gemeinsame Auswertung müssen neue Methoden adaptiert werden, da diese, wie Lienhart (2012) aufzeigt, nur unter Verwendung eines mechanischen ‘Bauwerkmodells erfolgen kann.
In vielen Ingenieurwissenschaften, wie z. B. dem Bauingenieurwesen, findet die Modellierung physikalisch-mechanischer Eigenschaften von Strukturen mithilfe der Finite-Elemente-Methode (FEM) statt. Die Verifizierung eines derartigen Modells erfolgt vorwiegend lediglich durch stellenweise Messung von z. B. Durchbiegungen und einer anschließenden Gegenüberstellung mit den berechneten Modellwerten. Dies ist meist der Tatsache geschuldet, dass für die FE-Modellierung in der Regel kommerzielle Programme verwendet werden, und somit auf viele Teilprozesse des Auswertealgorithmus nicht zugegriffen werden kann. Aus diesem Grund erfolgt in vielen akademischen Fragestellungen die FE-’Modellierung mit Open-Source-Software, wie z. B. FEniCS (2013) oder OpenSees (2013), wodurch auch eine kombinierte Auswertung von Messungen und Modell nach der Methode 'der kleinsten Quadrate ermöglicht wird.
In diesem Beitrag wird eine messungs- und modellbasierte Strukturanalyse (MeMoS) durch (die Integration der Finite-Elemente-Methode in die Ausgleichungsrechnung am Beispiel eines Vier-Punkt-Biegeversuchs vorgestellt. In numerischen Untersuchungen wird gezeigt, wie diese integrierte Analyse für eine Parameteridentifikation angewendet werden kann. Für diese Untersuchungen wird ein Finite-Elemente-Modell mit bekannten Randbedingungen und Materialeigenschaften aufgestellt. Die Durchbiegungen, die als Beobachtungen in die Ausgleichung eingehen, werden mithilfe von Simulationsrechnungen erzeugt; der zu fidentifizierende Parameter ist der Elastizitätsmodul eines Balkens.
Es wird untersucht, mit welcher Genauigkeit Durchbiegungsmessungen durchgeführt werden müssen und an welcher Stelle des Bauwerks diese Messungen erfolgen sollen, um den Elastizitätsmodul möglichst genau zu bestimmen. Des Weiteren wird der Einfluss der Anzahl der Messstellen auf den zu identifizierenden Parameter untersucht.
The integration of finite element method (FEM) into the least-squares adjustment presented in [1] is further extended for a joint evaluation of an elastostatic model and displacement field measurement. For linear solids which obey the HOOKE's law, the material parameters determination from measurements is being examined. In many literature, see for example [2], parameters are iteratively tuned until the computed FEM results are in accordance with the measurements. In contrast to these debatable approaches, we follow a rigorous and direct method. The “classical” FEM procedure starts with known material constants and ends up with computed fields such as dis-placement or temperature field. We present a method to invert the FEM procedure using the most general least-squares adjustment – the GAUSS-HELMERT Model (GHM). From given fields, the material parameters are directly calculated.