7.2 Ingenieurbau
Filtern
Erscheinungsjahr
- 2018 (40) (entfernen)
Dokumenttyp
- Vortrag (20)
- Beitrag zu einem Tagungsband (10)
- Posterpräsentation (4)
- Zeitschriftenartikel (3)
- Buchkapitel (1)
- Beitrag zu einem Sammelband (1)
- Dissertation (1)
Sprache
- Englisch (40) (entfernen)
Schlagworte
- Repair (4)
- Box-Behnken (3)
- Fatigue (3)
- Grouting (3)
- Interface (3)
- Statistical tests (3)
- Acoustic emission testing (2)
- Amplitude-charge weight laws (2)
- Amplitude-distance laws (2)
- Analysis of variance (2)
- Compressive cyclic loading (2)
- Compressive strength (2)
- Cracks (2)
- DUCON® (2)
- Ductility (2)
- E-modulus (2)
- Energy (2)
- Explosion-induced ground vibrations (2)
- Fault detection (2)
- Grouted Connection (2)
- Hammer impact (2)
- High-strength concrete (2)
- Impact (2)
- Micro-reinforcement (2)
- Mix design (2)
- Mobile elements (2)
- Non-destructive testing (2)
- Numerical model (2)
- Numerical modeling (2)
- Numerical modelling (2)
- Offshore (2)
- Prediction of explosion induced ground and building vibration (2)
- Quasi-static and dynamic tests (2)
- Rehabilitation (2)
- Residual evaluation (2)
- SHM (2)
- Size effect (2)
- Slab track (2)
- Slenderness effect (2)
- Soil properties (2)
- Soil-structure interaction (2)
- Stereo photogrammetry (2)
- Structural health monitoring (2)
- Supplementary cementitious materials (2)
- Track damage (2)
- UHPC (2)
- Ultrasonic testing (2)
- Uncertainty in reference (2)
- Vibration measurements (2)
- 3D imaging (1)
- Ballast track (1)
- Beanspruchungszustand (1)
- Boundary element method (1)
- Bridge (1)
- Cohesive soils (1)
- Compaction Grouting (1)
- Compaction grouting (1)
- Conductor (1)
- Crack detection (1)
- Crack repair (1)
- Cyclic axial shearing (1)
- DEM-LBM simulation (1)
- Damage detection (1)
- Decision matrix analysis (1)
- Design (1)
- Design methods (1)
- Design practice (1)
- Digital Image Correlation (1)
- Digital Image Correlation (DIC) (1)
- Environmental (1)
- Environmental changes (1)
- Erosion (1)
- Erosion of cohesive soils (1)
- Features (1)
- Finite element model updating (1)
- Finite-Elemente-Modellkalibrierung (1)
- Fly ash (1)
- Freileitung (1)
- GPA (1)
- GPU parallelisation (1)
- Geology (1)
- Geomechanics (1)
- Geomechanics of offshore foundations (1)
- Ground vibration measurements (1)
- Grout (1)
- Grout Injection (1)
- HTLS (1)
- Inspection planning (1)
- Interface model (1)
- Jet erosion test (1)
- LBM-DEM simulation (1)
- Laminography (1)
- Load bearing behaviour (1)
- Material Point Method (1)
- Material Point Method (MPM) (1)
- Material model (1)
- Metakaolin (1)
- Microfine cement (1)
- Micromechanical LBM-DEM simulation (1)
- Microsilica (1)
- Mixed formulation (1)
- Offshore Pile Foundation (1)
- Offshore pile foundation (1)
- Offshore pile foundations (1)
- Offshore wind energy (1)
- Offshore wind farms (1)
- Optimierungsmethoden (1)
- Optimization techniques (1)
- Physical phenomenology (1)
- Piaui state (1)
- Pile Capacity (1)
- Pile foundations (1)
- Pressure (1)
- Recovery experiments (1)
- Reinforced concrete (1)
- Reliability (1)
- Risk (1)
- Sandstone (1)
- Santa-marta (1)
- Schwingungsmessungen (1)
- Serra da cangalha (1)
- Shearing (1)
- Shrinkage (1)
- Soil erosion (1)
- Soil-pile interaction (1)
- State of stress (1)
- Statistical pattern recognition (1)
- Steel structures (1)
- Strength (1)
- Subspace methods (1)
- Subspace-based method (1)
- TOP (1)
- Temperature effect (1)
- Track vibration (1)
- Train configuration (1)
- Train passage (1)
- Train passages (1)
- Tran speed (1)
- Truss structures (1)
- Vibration measurement (1)
- Vibrations (1)
- Viscosity (1)
- Wave-Tower interaction (1)
- Windfarm wake analysis (1)
- Workability (1)
- fachwerkartige Stahltragwerken (1)
- temperature (1)
Organisationseinheit der BAM
- 7 Bauwerkssicherheit (40) (entfernen)
Eingeladener Vortrag
- nein (20)
This presentation deals with the phenomenology and design of pile foundations for offshore wind turbines, and is divided in two lectures.
The first lecture presents a brief introduction to the context and peculiarities of such foundations, and then focuses on the particular case of axially loaded piles. This part is most relevant for the relatively slender piles of the multi-pile substructures (i.e. jackets and tripods). A clear distinction between physical phenomenology and practical design is drawn here.
The second lecture continues with the case of lateraly loaded offshore piles, which bears most relevance for the case of the monopile foundations. Here again, a clear separation between physical reality and design methods is intended.
Finally, the last part of the second lecture introduces several advanced topics which lie outside the classical design approaches, namely the cyclic pile fatigue and the so-called pile setup (i.e. the time effects on the axial pile capacity). The relevance of these two topics is illustrated with experimental results from a field testing campaign on real large-scale piles.
This talk provides a brief introduction on general engineering aspects of offshore wind energy production. Some geomechanical issues for the foundation of OWTs into the seabed are introduced, while the results from experimental investigations and coupled computational analysis are discussed.
In the second part of the seminar, the hydromechanical Wave–Tower interaction is firstly discussed. Then, some general aspects of the windfarm aerodynamics are introduced. On the one hand, some modelling possibilities for the wake analysis of single turbines and turbine groups are discussed. And on the other hand the relevance of such analyses for a proper windfarm layout optimization is pointed out.
Concerning the geomechanical issues the talk shows that: i) The pile’s bearing capacity can degrade under cyclic loading (waves, wind, …). ii) The time effects can be relevant: Capacity improvement can be substantial, but also fragile. iii) There are cyclic PWP effects: Cyclic interaction with pore water may lead to soil softening and an uncoupled analysis (current design practice) is potentially unsafe.
And concerning the hydromechanical and aerodynamical design considerations, this seminar shows that: i) Numerical analysis of turbine’s interaction with wind/waves is useful and affordable. ii) Simplified models can provide insight into windfarm aerodynamics. iii) Turbulent wake analysis is very relevant for the windfarm layout.
Automatic vibration-based structural health monitoring has been recognized as a useful alternative or addition to visual inspections or local non-destructive testing performed manually. It is, in particular, suitable for mechanical and aeronautical structures as well as on civil structures, including cultural heritage sites. The main challenge is to provide a robust damage diagnosis from the recorded vibration measurements, for which statistical signal processing methods are required. In this chapter, a damage detection method is presented that compares vibration measurements from the current system to a reference state in a hypothesis test, where data9
related uncertainties are taken into account. The computation of the test statistic on new measurements is straightforward and does not require a separate modal identification. The performance of the method is firstly shown on a steel frame structure in a laboratory experiment. Secondly, the application on real measurements on S101 Bridge is shown during a progressive damage test, where damage was successfully detected for different damage scenarios.
The worldwide spread of windfarms brings new challenges, especially for concrete structures as a part of towers, connecting joints and foundations of wind turbines. High-cyclic loadings in such structures lead to a high relevance of the subject of fatigue. A proper assessment of the fatigue strength of concrete demands therefore a basis of reliable experimental data and the development of standardized testing methods. This article presents first results of an ongoing research program of BAM (Bundesanstalt für Materialforschung und -prüfung) which is a part of a joint project (WinConFat) funded by the German Federal Ministry for Economic Affairs and Energy. The subproject investigates the effects of size and slenderness of the specimens on the fatigue behaviour of high strength concrete at different stress levels. Not only the fatigue strength, but also the fatigue process itself is monitored by means of several measurement methods. Strain measurements are used to calculate the load dependent elastic modulus in the fatigue hysteresis as indicators for fatigue development. Furthermore, the application of non-destructive methods like acoustic emission analysis and ultrasonic measurement in laboratory tests gives a deeper insight into damage processes under cyclic loading. The results shall be used to improve design rules for concrete members under fatigue load and to develop or improve non-destructive techniques for in-service structural health monitoring.
The worldwide spread of windfarms brings new challenges, especially for concrete structures as a part of towers, connecting joints and foundations of wind turbines. High-cyclic loadings in such structures lead to a high relevance of the subject of fatigue. A proper assessment of the fatigue strength of concrete demands therefore a basis of reliable experimental data and the development of standardized testing methods. This article presents first results of an ongoing research program of BAM (Bundesanstalt für Materialforschung und -prüfung) which is a part of a joint project (WinConFat) funded by the German Federal Ministry for Economic Affairs and Energy. The subproject investigates the effects of size and slenderness of the specimens on the fatigue behaviour of high strength concrete at different stress levels. Not only the fatigue strength, but also the fatigue process itself is monitored by means of several measurement methods. Strain measurements are used to calculate the load dependent elastic modulus in the fatigue hysteresis as indicators for fatigue development. Furthermore, the application of non-destructive methods like acoustic emission analysis and ultrasonic measurement in laboratory tests gives a deeper insight into damage processes under cyclic loading. The results shall be used to improve design rules for concrete members under fatigue load and to develop or improve non-destructive techniques for in-service structural health monitoring.
The authors are currently investigating the possibility to apply compaction grouting for offshore pile foundations (Jacket piles as well as monopiles) as a possible retrofitting technique for an optimised foundation concept. In this research project, we are developing a design approach aiming to predict the ideal amount and properties of a grout for a specific soil situation and desired improvement of pile bearing capacity after Installation and during service time. Both numerical and experimental tests have been carried out to investigate the injection process during which a highly viscous grout is injected into the soil under high pressure to displace and compact the surrounding soil without fracturing it. The implicit Material Point Method (MPM) based on a mixed formulation is the numerical technique chosen to deal with the expected large deformations and the arbitrary shape of the developing grout bulb. The usage of MPM prevents both the need of remeshing and the numerical instability induced by extensive mesh distortion. For validation with experimental results, we have constructed a testing chamber with one transparent sidewall. This chamber enables us to observe the injection process directly at the transparent vertical window and to measure the in-plane soil displacements and strains by means of the Digital Image Correlation (DIC) technique.
The results already reveal the interrelation of soil and grout properties for a successful usage of this common ground improvement technique.
The authors are currently investigating the possibility to apply compaction grouting for offshore pile foundations (Jacket piles as well as monopiles) as a possible retrofitting technique for an optimised foundation concept. In this research project, we are developing a design approach aiming to predict the ideal amount and properties of a grout for a specific soil situation and desired improvement of pile bearing capacity after Installation and during service time. Both numerical and experimental tests have been carried out to investigate the injection process during which a highly viscous grout is injected into the soil under high pressure to displace and compact the surrounding soil without fracturing it. The implicit Material Point Method (MPM) based on a mixed formulation is the numerical technique chosen to deal with the expected large deformations and the arbitrary shape of the developing grout bulb. The usage of MPM prevents both the need of remeshing and the numerical instability induced by extensive mesh distortion. For validation with experimental results, we have constructed a testing chamber with one transparent sidewall. This chamber enables us to observe the injection process directly at the transparent vertical window and to measure the in-plane soil displacements and strains by means of the Digital Image Correlation (DIC) technique.
The results already reveal the interrelation of soil and grout properties for a successful usage of this common ground improvement technique.
Within the presented research project, experimental and numerical investigations were performed to develop a thin-shelled, modular, mobile element system made of a micro-reinforced ultra-high-performance ductile concrete (DUCON®). Material parameters were experimentally determined to adapt the material model within the numerical analysis applying the Drucker-Prager relationship. Afterwards, for validation of the numerical models, quasi-static and high-velocity impact tests were performed on plate-like structures. Finally, a suitable geometry of transportable barrier elements will be designed, which provides a maximum of resistance against impact by a minimum of weight and a maximum of mobility.
This work describes a vibration-based structural health monitoring of a prestressed-concrete box girder bridge on the A100 Highway in Berlin by applying statistical pattern recognition technique to a huge amount of data continuously collected by an integrated monitoring system during the period from 2000 to 2013. Firstly, the general condition and potential damage of the bridge is described. Then, the dynamic properties are extracted from 20 velocity sensors. Environmental variability captured by five thermal transducers and traffic intensity approximately estimated by strain measurements are also reported. Nonlinear influences of temperature on natural frequencies are observed. Subsequently, the measurements during the first year are used to build a baseline health index. The multiple linear regression (MLR) method is used to characterize the nonlinear relationship between natural frequencies and temperatures. The Euclidean distance of the residual errors is calculated to build a statistical health index. Finally, the indices extracted from the following years gradually deviate; which may indicate structural deterioration due to loss of prestress in the prestressed tendons.
In recent years, several high temperature low sag conductors (HTLS) have been developed and are now commercially available. Very few utilities have long-term experience with all the technologies. Moreover, most of the operational experience is at low temperatures. An independent testing program at maximum operational temperatures comparing most of the available technologies would provide useful guidance to utilities considering using such conductors.
This paper describes the approach and results of an international research project assessing the long-term reliability of a wide range of commercially available high temperature conductor systems. Each system was exposed to 4,400 hours of simultaneous mechanical and electrical stresses. A set of standard mechanical and electrical tests were carried out to determine any changes. A conventional ACSR conductor was also tested and provided a validation that the testing program was realistic.
The majority of the conductor systems performed satisfactorily. However the ACSS system joint resistance and the grease on the TACSR performed poorly.