TY  - CHAP
A1  - Ebert, Matthias
A1  - Bucher, Christian
T1  - Modelling of changing of dynamic and static parameters of damaged R/C
N2  - Dynamic testing for damage assessment as non-destructive method has attracted growing in-terest for systematic inspections and maintenance of civil engineering structures. In this con-text the paper presents the Stochastic Finite Element (SFE) Modeling of the static and dy-namic results of own four point bending experiments with R/C beams. The beams are dam-aged by an increasing load. Between the load levels the dynamic properties are determined. Calculated stiffness loss factors for the displacements and the natural frequencies show differ-ent histories. A FE Model for the beams is developed with a discrete crack formulation. Cor-related random fields are used for structural parameters stiffness and tension strength. The idea is to simulate different crack evolutions. The beams have the same design parameters, but because of the stochastic material properties their undamaged state isn't yet the same. As the structure is loaded a stochastic first crack occurs on the weakest place of the structure. The further crack evolution is also stochastic. These is a great advantage compared with de-terministic formulations. To reduce the computational effort of the Monte Carlo simulation of this nonlinear problem the Latin-Hypercube sampling technique is applied. From the results functions of mean value and standard deviation of displacements and frequencies are calcu-lated. Compared with the experimental results some qualitative phenomena are good de-scribed by the model. Differences occurs especially in the dynamic behavior of the higher load levels. Aim of the investigations is to assess the possibilities of dynamic testing under consideration of effects from stochastic material properties
KW  - Stahlbetonbauteil
KW  - Bruchmechanik
KW  - Dynamische Belastung
KW  - Statische Last
KW  - Finite-Elemente-Methode
KW  - Stochastisches Modell
Y1  - 2000
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20111215-5825
ER  - 
TY  - THES
A1  - Ebert, Matthias
T1  - Experimentelle und numerische Untersuchung des dynamischen Verhaltens von Stahlbetontragwerken unter Berücksichtigung stochastischer Eigenschaften
N2  - Der Zusammenhang zwischen Schädigung und der Veränderung dynamischer und statischer Eigenschaften von Stahlbetonstrukturen wird untersucht. Auf der einen Seite stehen die statischen Lastversuche in Verbindung mit dynamischen Experimenten an Stahlbetonstrukturen (Platten und Balken). Auf der anderen Seite wird für die Balkenstrukturen ein nichtlineares Stochastisches Finite Elemente Modell entwickelt. Dies berücksichtigt zufällige Material- und Festigkeitseigenschaften durch räumlich korrelierte Zufallsfelder. So werden stochastische Rissentwicklungen für den Stahlbeton simuliert. Für die Berechnungen vieler Realisationen und damit verschiedenartige "Lebensgeschichten" einer Struktur wird als Monte Carlo Methode Latin Hypercube Sampling verwendet. Die Auswertung der Strukturantworten für die Lastgeschichte zeigt den Einfluss der zufälligen Eigenschaften auf die Schädigungsentwicklung. Die Arbeit leistet einen Beitrag zur Bewertung und zum zukünftigen Einsatz dynamischer Untersuchungsmethoden im Bauwesen.
N2  - The relation between damage and the changing of dynamic and static properties of R/C structures is investigated. On the one side static experiments in relation with dynamic experiments of R/C structures (plates and beams) are performed. On the other side a nonlinear Stochastic Finite Element Model is developed. The model considers stochastic material and strength properties by spatial correlated random fields. So a random crack evolution for the R/C beams are simulated. As Monte Carlo Method Latin Hypercube Sampling is used to calculate a lot of samples and so various "live histories" of the structure. The evaluation of structure response for the load history indicates the influence of stochastic properties on the damage evolution. The work gives a contribution to the assessment and the use of dynamic investigation methods in the future in civil engineering.
KW  - Stahlbetonkonstruktion
KW  - Tragverhalten
KW  - Stochastische Analysis
KW  - Dynamische Belastung
KW  - Nichtlineare Finite-Elemente-Methode
KW  - Monte-Carlo-Methode
KW  - reinforced concrete
KW  - dynamic behavior
KW  - stochastics
KW  - nonlinear finite elements
KW  - Monte Carlo method
Y1  - 2002
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20040302-531
ER  -