References of "Bungard, Volker 40000109"
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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 ▲]

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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 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)

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See detailCondition assessment of concrete structures and bridges using vibration monitoring in comparison to changes in their static properties
Bungard, Volker UL

Doctoral thesis (2010)

The thesis deals with the non-destructive condition assessment of civil engineering structures made of reinforced and prestressed concrete as well as bridges and concentrates on a comparison of static and ... [more ▼]

The thesis deals with the non-destructive condition assessment of civil engineering structures made of reinforced and prestressed concrete as well as bridges and concentrates on a comparison of static and dynamic investigation methods. The main questions discuss the sensitivity of changes in static as well as in dynamic properties during the mechanical lifetime of those types of structures under laboratory conditions, the sensitivity of these changes when testing in-situ and the dimension of undesired environmental influences on the dynamic properties. Therefore, a gradually loaded laboratory reinforced concrete beam (cp. chapter 7) and a reinforced as well as a prestressed concrete slab (cp. chapter 8) are investigated for changes in their static and dynamic parameters until reaching their ultimate loads. Furthermore, a successively damaged and stepwise loaded laboratory reinforced concrete slab and a prestressed concrete slab (cp. also chapter 8) are under investigation and also compared in changes in their static as well as in dynamic properties during their lifetimes. By means of static and dynamic tests on a successively damaged and stepwise loaded prestressed concrete bridge (cp. chapter 9) it was possible to investigate the amount of changes in static and dynamic properties for a real in-situ object. A long-term measurement of a composite bridge (cp. chapter 10) demonstrates the environmental influences on the static and dynamic properties of a system which have to be considered when conducting comparative non-destructive condition assessment techniques on real objects. All tests are calculated respectively simulated by the method of the integration of stress (cp. chapter 6) or the finite element method by using the softwares ANSYS and SOFISTIK. Furthermore, measured eigenfrequencies and modeshapes are used to adapt finite element models with the aim to improve the model or to locate and quantify damaged areas. The work is a contribution to the application of non-destructive static and dynamic condition assessment methods on civil engineering structures made of concrete in the sector of civil engineering. [less ▲]

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See detailStatische und dynamische Zustandsbewertung von Stahlbetonbauteilen
Bungard, Volker UL; Waldmann, Danièle UL

in Abstract book of 51. Forschungskolloquium des Deutschen Ausschusses für Stahlbetonbau (2010)

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See detailAmbient Vibration and Forced Excitation Tests of a Composite Bridge: Environmental influences and nonlinear effects on the dynamic properties
Bungard, Volker UL; Mahowald, Jean UL; Waldmann, Danièle UL et al

in Proceedings of the International Conference on Noise and Vibration Engineering, ISMA (2010)

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See detailComparison of linear and nonlinear static and dynamic behaviour of prestressed and non-prestressed concrete slab elements
Mahowald, Jean UL; Bungard, Volker UL; Maas, Stefan UL et al

in Proceedings of the International Conference of Noise and Vibration Engineering (2010)

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See detailComparison of static behaviour and nonlinear vibration characteristic of gradually damaged prestressed concrete slabs and reinforced concrete beams
Bungard, Volker UL; Waltering, Markus UL; Waldmann, Danièle UL et al

in Proceedings of the International Conference on Experimental Vibration Analysis for Civil Engineering Structures (2009)

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See detailDamage assessment of a gradually damaged pre-stressed concrete bridge using static load tests and non-linear vibration characteristic
Waltering, Markus UL; Bungard, Volker UL; Maas, Stefan UL et al

in International Conference on Noise and Vibration Engineering (2008)

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See detailNon-destructive Damage Assessment Using Non-linear Vibration
Waltering, Markus UL; Bungard, Volker UL; Maas, Stefan UL et al

in International Modal Analysis Conference, IMAC-XXVI (2008)

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See detailStructural Health Monitoring of a Composite Bridge
Bungard, Volker UL; Waltering, Markus UL; Waldmann, Danièle UL et al

in International Modal Analysis Conference (IMAC-XXVI) (2008)

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See detailDamage Assessment of Civil Engineering Structures by the Observation of Non-linear Dynamic Behaviour
Waltering, Markus UL; Bungard, Volker UL; Waldmann, Danièle UL et al

in Proceedings of the International Conference on Experimental Vibration Analysis for Civil Engineering Structures (2007)

Detailed reference viewed: 73 (17 UL)