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See detailStabilité de systèmes de murs en blocs de béton emboîtables sans joints en mortier
Agaajani, Shahriar; Waldmann, Danièle UL

Scientific Conference (2012)

Detailed reference viewed: 54 (11 UL)
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See detailStatic and dynamic testing on prestressed concrete slab elements with artificial bond deficiencies
Mahowald, Jean UL; Maas, Stefan UL; Waldmann, Danièle UL et al

in Proceedings of the 4th Bond in Concrete Conference, Vol. 1: General Aspects of Bond (2012)

Detailed reference viewed: 104 (21 UL)
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See detailDamage Identification and Localisation Using Changes in Modal Parameters for Civil Engineering Structures
Mahowald, Jean UL; Maas, Stefan UL; Waldmann, Danièle UL et al

in Proceedings of the International Conference on Noise and Vibration Engineering (2012)

Detailed reference viewed: 114 (37 UL)
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See detailExperimental and Numerical Investigation on Postcracking Behavior of Steel Fiber Reinforced Concrete
Michels, Julien; Christen, Christen; Waldmann, Danièle UL

in Engineering Fracture Mechanics (2012) (2012)

Detailed reference viewed: 102 (9 UL)
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See detailDynamic damage identification using linear and nonlinear testing methods on a two-span prestressed concrete bridge
Mahowald, Jean UL; Maas, Stefan UL; Scherbaum, Frank UL et al

in Proceedings of the Third International Symposium on Life-Cycle Civil Engineering, IALCCE’12 (2012)

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See detailShear Stresses in Honeycomb Sandwich Plates: Analytical Solution, Finite Elemente Method and Experimental Verification
Wahl, Laurent UL; Maas, Stefan UL; Waldmann, Danièle UL et al

in Journal of Sandwich Structures & Materials (2012), 14(4), 449-468

Honeycomb composite structures are used in airplanes, railway cars and vehicles. The sandwich panels consist of two stiff face sheets of aluminium, which are bonded to a very lightweight honeycomb core of ... [more ▼]

Honeycomb composite structures are used in airplanes, railway cars and vehicles. The sandwich panels consist of two stiff face sheets of aluminium, which are bonded to a very lightweight honeycomb core of aluminium. Compared to normal plates, sandwich panels have a very high stiffness and simultaneously a low weight. The core of these structures is mainly subjected to shear stresses. The shear stresses depend strongly on the angle of the load application. The distribution and the level of the shear stresses are investigated using analytical calculations. The load direction which induces highest stresses in the honeycomb core is derived. This direction is not the W-direction, which is the most compliant one. When doing finite element simulations of honeycomb cores, often the core is homogenized in order to reduce the calculation time. In this article, some equations are derived in order to calculate the real shear stresses from the shear stresses of the homogeneous core. The equations are validated by finite element simulations and partially by tests. Three-point bending tests and additionally some Food Cart Roller Tests were conducted in order to test the panels in different angles. [less ▲]

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See detailShear stresses in honeycomb sandwich plates: Analytical solution, finite element method and experimental verification
Wahl, Laurent UL; Maas, Stefan UL; Waldmann, Danièle UL et al

in Journal of Sandwich Structures & Materials (2012), 4

Honeycomb composite structures are used in airplanes, railway cars and vehicles. The sandwich panels consist of two stiff face sheets of aluminium, which are bonded to a very lightweight honeycomb core of ... [more ▼]

Honeycomb composite structures are used in airplanes, railway cars and vehicles. The sandwich panels consist of two stiff face sheets of aluminium, which are bonded to a very lightweight honeycomb core of aluminium. Compared to normal plates, sandwich panels have a very high stiffness and simultaneously a low weight. The core of these structures is mainly subjected to shear stresses. The shear stresses depend strongly on the angle of the load application. The distribution and the level of the shear stresses are investigated using analytical calculations. The load direction which induces highest stresses in the honeycomb core is derived. This direction is not the W-direction, which is the most compliant one. When doing finite element simulations of honeycomb cores, often the core is homogenized in order to reduce the calculation time. In this article, some equations are derived in order to calculate the real shear stresses from the shear stresses of the homogeneous core. The equations are validated by finite element simulations and partially by tests. Three-point bending tests and additionally some Food Cart Roller Tests were conducted in order to test the panels in different angles. [less ▲]

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See detailDamage Detection on the Champangshiehl Bridge using Blind Source Separation
Nguyen, Viet Ha UL; Rutten, Christophe; Golinval, Jean-Claude et al

in Proceedings of the Third International Symposium on Life-Cycle Civil Engineering, IALCCE’12 (2012)

Detailed reference viewed: 103 (23 UL)
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See detailDamage assessment of concrete structures through dynamic testing methods. Part 1 - Laboartory Test
Maas, Stefan UL; Zürbes, Arno; Waldmann, Danièle UL et al

in Journal of Engineering Structures (2012), 34

The present paper is split into two parts: Part 1 is about laboratory tests whereas the second part deals with experiments on real bridges. This article aims at summarizing several experimental dynamic ... [more ▼]

The present paper is split into two parts: Part 1 is about laboratory tests whereas the second part deals with experiments on real bridges. This article aims at summarizing several experimental dynamic testing methods with different damage indicators to evaluate the state of prestressed as well as of passively reinforced concrete structures. First the differences between prestressed and passively reinforced concrete are repeated for static behavior, before the transition to dynamics is made. As it will be proved in the following that the amount of nonlinearities increases with damage, harmonic excitation is favorable to realize good testing conditions. It is applied to visualize variations in linear as well as in non-linear structural characteristics, which are subsequently used as damage indicators, e.g. the drop of the eigenfrequencies, the changes in damping and modeshapes, the occurrence of higher harmonics and a varying dependency of the eigenfrequency on excitation force amplitude. These different indicators will be used on passively reinforced beam elements and industrially produced prestressed slabs in the first part and on two real post-tensioned bridges in the second part. All these structures were in good order and condition before artificial damage was applied in multiple steps and the sensitivity of each damage indicator was analyzed. [less ▲]

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See detailDamage assessment of concrete structures through dynamic testing methods. Part 2: Bridge tests
Maas, Stefan UL; Zürbes, Arno; Waldmann, Danièle UL et al

in Engineerig Structures (2012), 34

The present paper is split into two parts: in the first part the different dynamic damage indicators are defined and applied to beam and slab structures under laboratory conditions, whereas the present ... [more ▼]

The present paper is split into two parts: in the first part the different dynamic damage indicators are defined and applied to beam and slab structures under laboratory conditions, whereas the present second part deals with experiments carried out on two real post-tensioned bridges. The damage indicators defined in part one are based on swept sine excitation and esveal the drop of the eigenfrequencies, the changes in damping, the varying dependency range of the first eigenfrequency on excitation force amplitude and the occurrence of higher harmonics, which changed the Total Harmonic Distorsion (THD) and a special transfer-function called TF or FRFsmall. In the first part it was proved that the amount of nonlinearities varies with damage and that harmonic excitation is favorable for good test conditions. In the laboratory this can easily be done using an electric or hydraulic shaker, but on real bridges this kind of excitation becomes more complicated due to the higher forces and the necessity to provide counter bearing for any shaker system. That is why two machines were designed and used to excite big structures harmonically, e.g. real bridges in this part. The different indicators are applied to assess the state of two post-tensioned bridges, which had been in good order and condition before artificial damage in multiple steps was caused. It turns out that the decrease in the eigenfrequencies is the most important damage indicator, provided temperature and mass dependant effects can be eliminated. All other indicators may be used as supplements to give correct tendencies, but no strict limits. [less ▲]

Detailed reference viewed: 147 (27 UL)
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See detailNouveaux systèmes de murs isolants en béton
Agaajani, Shariar; Waldmann, Danièle UL

in RF2B 2011 – 12ème édition des Journées scientifiques du Regroupement francophone pour la recherche et la formation sur le béton (2011)

Detailed reference viewed: 85 (20 UL)
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See detailInfluence of environmental changes on modal characteristics
Waldmann, Danièle UL; Bungard, Volker UL; Mahowald, Jean UL et al

in Federation for Structural Concrete (fib) (2011)

Detailed reference viewed: 71 (22 UL)
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See detailSteel fibres as only reinforcement for flat slab construction
Julien, Michels; Waldmann, Danièle UL; Maas, Stefan et al

in Construction and Building Materials (2011)

Detailed reference viewed: 22 (4 UL)
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See detailFatigue in Aluminium Honeycomb-core Plates
Wahl, Laurent UL; Zürbes, Arno UL; Maas, Stefan UL et al

in Benchmark: The International Magazine for Engineering Designers & Analysts (2011), (January), 26-32

Honeycomb composite lightweight structures made of aluminium or aramid fibres are used in airplanes, railway carriages and automobiles. These structures are subjected to dynamic loading but hardly any ... [more ▼]

Honeycomb composite lightweight structures made of aluminium or aramid fibres are used in airplanes, railway carriages and automobiles. These structures are subjected to dynamic loading but hardly any fatigue properties of the honeycomb core exist in current literature. Hence here a theoretical and experimental approach is presented. [less ▲]

Detailed reference viewed: 168 (10 UL)
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See detailInfluence of environmental conditions for the rheological properties of SCC
Weisheit, Sandro UL; Waldmann, Danièle UL; Greger, Manfred UL

in Professeur D. SC. A. Kamal H. Khayat (Ed.) CD-Proceedings, Paper ID: MS-096 (2010, September 28)

Detailed reference viewed: 49 (4 UL)
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See detailStudy of the vibrating stationary state of a sheet pile during a vibratory pile driving
Hanus, Vincent; Zürbes, Arno; Maas, Stefan et al

in Proceedings of ISMA 2010 - International Conference on Noise and Vibration Engineering (2010, September 20)

Detailed reference viewed: 22 (1 UL)