7.2 Ingenieurbau
Filtern
Dokumenttyp
- Vortrag (113)
- Beitrag zu einem Tagungsband (66)
- Zeitschriftenartikel (52)
- Posterpräsentation (8)
- Buchkapitel (3)
- Beitrag zu einem Sammelband (3)
- Dissertation (3)
- Sonstiges (1)
Sprache
- Englisch (249) (entfernen)
Schlagworte
- Ground vibration (20)
- Fatigue (15)
- Structural health monitoring (13)
- Offshore (10)
- Offshore wind energy (10)
- Hammer impact (9)
- Impact (9)
- Structural Health Monitoring (9)
- Train passage (9)
- Damage characterization (8)
- Model interpolation (8)
- Planar tomography (8)
- Structural systems (8)
- Vibration measurements (8)
- Building vibration (7)
- Damage detection (7)
- Deterioration (7)
- Layered soil (7)
- Reliability (7)
- Slab track (7)
- Soil-structure interaction (7)
- Train-induced ground vibration (7)
- Compressive strength (6)
- Design methods (6)
- Grout (6)
- Inspection (6)
- Numerical modelling (6)
- Offshore wind turbines (6)
- Physical phenomenology (6)
- Pile foundations (6)
- Reinforced concrete structure (6)
- Environmental effects (5)
- Interface (5)
- Layered soils (5)
- Monitoring (5)
- Numeric simulation (5)
- Repair (5)
- Temperature rejection (5)
- Ultrasonic testing (5)
- Bayesian updating (4)
- Container loading (4)
- Crack detection (4)
- Damage localization (4)
- Drop test (4)
- Erosion (4)
- Excitation forces (4)
- Fault detection (4)
- Foundation load (4)
- Foundations (4)
- High-strength concrete (4)
- Inspection planning (4)
- Mitigation (4)
- Offshore geomechanics (4)
- Statistical tests (4)
- Steel structures (4)
- Subspace methods (4)
- Subspace-based method (4)
- Vehicle-track-soil interaction (4)
- Vibration measurement (4)
- Wind (4)
- Wind Energy (4)
- Ansys Autodyn (3)
- Attenuation (3)
- Axle impulses (3)
- Box-Behnken (3)
- Bridge (3)
- Bridges (3)
- Buckling (3)
- Compaction Grouting (3)
- Cracks (3)
- DUCON® (3)
- Deep foundations (3)
- Drucker-Prager (3)
- Ductility (3)
- E-modulus (3)
- Earth masonry (3)
- Filter effects (3)
- Fly ash (3)
- Grouted connection (3)
- Grouting (3)
- Irregular soil (3)
- Linear parameter varying systems (3)
- Load vector (3)
- Maintenance (3)
- Material moisture (3)
- Metakaolin (3)
- Micro-reinforcement (3)
- Micromechanical modelling (3)
- Mobile elements (3)
- Monopiles (3)
- Numerical modeling (3)
- Offshore Pile Foundation (3)
- Offshore foundations (3)
- Offshore wind turbine (3)
- Physical testing (3)
- Post-impact evaluation (3)
- Probabilistic (3)
- Quasi-static and dynamic tests (3)
- Railway (3)
- Railway bridge (3)
- Randomly heterogeneous soil (3)
- Rehabilitation (3)
- Reinforced concrete (3)
- Risk (3)
- SHM (3)
- Scattering (3)
- Shell Buckling (3)
- Soil erosion (3)
- Statistical evaluation (3)
- Statistical method (3)
- Stereo photogrammetry (3)
- Subspace-based residual (3)
- Train speed (3)
- UHPC (3)
- Vehicle-track interaction (3)
- Vibration (3)
- Vibrations (3)
- 2-span bridge (2)
- Acceleration sensors (2)
- Achsfolgespektren (2)
- Acoustic emission testing (2)
- Amplitude-charge weight laws (2)
- Amplitude-distance laws (2)
- Analysis of variance (2)
- Apartment building (2)
- Artificial Intelligence (2)
- Artificial intelligence (2)
- Axle sequence (2)
- Axle-sequence spectrum (2)
- Ballast track (2)
- Bauteile (2)
- Bauwerke (2)
- Bayesian System Identification (2)
- Bayesian analysis (2)
- Bayesian methods (2)
- Bayesian system identification (2)
- Brücken (2)
- Cable failure (2)
- Cable-stayed bridge (2)
- Changing process noise (2)
- Chemisoprtion (2)
- Climate chamber (2)
- Compressive Cyclic loading (2)
- Compressive cyclic loading (2)
- Computer Vision (2)
- Concrete (2)
- Coupled fluid-particle simulation (2)
- Coupler systems (2)
- Crack Luminescence (2)
- Crack formation (2)
- Crack pattern (2)
- Cyclic load (2)
- DEM (2)
- Damage identification (2)
- Design (2)
- Digital twin (2)
- Displacements (2)
- Drone (2)
- Earth block masonry (2)
- Energy (2)
- Evaluation (2)
- Explosion-induced ground vibrations (2)
- Finite element models (2)
- Freight train (2)
- GPU parallel computation (2)
- Ground vibration measurements (2)
- Grouted Connection (2)
- High-performance computing (2)
- High-speed (2)
- High-speed train (2)
- Injection Sequence (2)
- Irregular ballast (2)
- Irregularities (2)
- Jacket support structure (2)
- Jet erosion test (2)
- Knudsen effect (2)
- LBM-DEM (2)
- Laboratory beam structure (2)
- Long-term shrinkage (2)
- Macromechanical Sample Strength (2)
- Material tests (2)
- Measurement (2)
- Measurements (2)
- Micro silica (2)
- Micromechanical Tensile Failure (2)
- Mix design (2)
- Modal Analysis (2)
- Modalanalyse (2)
- Model updating (2)
- Moisture content (2)
- Molecular diffusion (2)
- Non destructive testing (2)
- Non-Destructive Evaluation (2)
- Non-destructive testing (2)
- Numerical model (2)
- Office tower (2)
- Offshore Wind Energy (2)
- Offshore geotechnics (2)
- Offshore wind (2)
- Optimal Sensor Placement (2)
- Passenger train (2)
- Physisorption (2)
- Pile Foundation (2)
- Prediction (2)
- Prediction of explosion induced ground and building vibration (2)
- Probability of Detection (2)
- Railway tunnel (2)
- Railways (2)
- Reinforcement (2)
- Relative humidity (2)
- Research data management (2)
- Residual evaluation (2)
- Resonance (2)
- SDDLV (2)
- Safety (2)
- Scattered axle impulses (2)
- Size effect (2)
- Slenderness effect (2)
- Soil properties (2)
- Soil-Structure-Interaction (2)
- Soil-pile interaction (2)
- Soil-wall-floor model (2)
- Static axle loads (2)
- Static load (2)
- Suction bucket (2)
- Supplementary cementitious materials (2)
- Surface-tunnel reduction (2)
- System Identification (2)
- System identification (2)
- Temperature effects (2)
- Tensile Capacity (2)
- Time-variant reliability (2)
- Tomographic damage evaluation (2)
- Track damage (2)
- Track-soil interaction (2)
- Train excitation (2)
- Uncertainty (2)
- Uncertainty in reference (2)
- Uncertainty quantification (2)
- Value of Information (2)
- Vehicle–track interaction (2)
- Wind Turbines (2)
- Wind energy (2)
- Wind turbine tower (2)
- Windenergy (2)
- 3D imaging (1)
- Acoustic emission (1)
- Acoustic emission analysis (1)
- Ambient excitation (1)
- Analytical Design Methods (1)
- Assessment (1)
- Asymptotic local approach (1)
- Automated Modal Analysis for Tracking Structural Change during Construction and Operation Phases (1)
- Automated operational modal analysis (1)
- Automatic modal parameters identification (1)
- Autonomous underwater vehicles (1)
- Axial load bearing (1)
- Axle loads (1)
- Axle pulses (1)
- BIM (1)
- Base isolation (1)
- Bayes'sche Analyse (1)
- Beanspruchungszustand (1)
- Benchmark (1)
- Blast (1)
- Blast tests (1)
- Boundary element (1)
- Boundary element method (1)
- Bridge monitoring (1)
- Bridge resonance (1)
- Bridge vibration (1)
- Buckling piles circular shells (1)
- Buckling soil-structure-interaction offshore piles track (1)
- Building and Construction (1)
- Building information modelling (1)
- Building response (1)
- CFD (1)
- Cancellation (1)
- Cars (1)
- Cement-based composites (1)
- Chemisorption (1)
- Civil and Structural Engineering (1)
- Civil structures (1)
- Coating (1)
- Cohesive granular materials (1)
- Cohesive soils (1)
- Column/wall resonance (1)
- Combined finite-element boundary-element method (1)
- Compaction grouting (1)
- Compliance function (1)
- Components of excitation (1)
- Compression tests (1)
- Computational (1)
- Condensed Matter Physics (1)
- Conductor (1)
- Continuous soil (1)
- Continuously inhomogeneous geological media (1)
- Continuously inhomogeneous soils (1)
- Crack damage detection (1)
- Crack growth (1)
- Crack repair (1)
- Cyber security (1)
- Cyclic axial shearing (1)
- Cyclic degradation (1)
- DEM-LBM simulation (1)
- Damage Detection (1)
- Damage evolution (1)
- Decision matrix analysis (1)
- Design models (1)
- Design practice (1)
- Digital Image Correlation (1)
- Digital Image Correlation (DIC) (1)
- Digital Models (1)
- Digital Twin (1)
- Discrete Element Method (1)
- Discrete element method (1)
- Drop Test (1)
- Drop Tests (1)
- Drop tower (1)
- Dynamic axle loads (1)
- Dynamic loads (1)
- Dynamic soil properties (1)
- EERA Joint Program (1)
- Earth blocks (1)
- Earth material (1)
- Earthen hydraulic constructions (1)
- Earthen hydraulic infrastructures (1)
- End-of-life decision making (1)
- Environmental (1)
- Environmental changes (1)
- Environmental influence (1)
- Erosion of cohesive soils (1)
- Estimation (1)
- FEM (1)
- FEM analysis (1)
- Fatigue deterioration (1)
- Fatigue strength (1)
- Fault detectionchanging (1)
- Features (1)
- Fequency domain (1)
- Fiber optic sensing (1)
- Fibre optic sensors (1)
- Finite element (1)
- Finite element analysis (1)
- Finite element method (1)
- Finite element model updating (1)
- Finite elements (1)
- Finite-Elemente-Modellkalibrierung (1)
- Finite-element boundary-element method (1)
- Flexibility (1)
- Flexible car body (1)
- Flexible wheelset (1)
- Floor resonance (1)
- Floors (1)
- Fluid-structure interaction (1)
- Footbridge (1)
- Force reconstruction (1)
- Foundation Pile (1)
- Foundation reliability analysis (1)
- Freileitung (1)
- Frequency response function (1)
- GMNIA (1)
- GPA (1)
- GPU Parallel computing (1)
- GPU parallelisation (1)
- General Materials Science (1)
- Geology (1)
- Geomechanics (1)
- Geomechanics of offshore foundations (1)
- Geometric vehicle and track irregularities (1)
- Global ambient vibrations (1)
- Granular Cohesive Materials (1)
- Granular Cohesive Materials, (1)
- Granular cohesion (1)
- Ground (1)
- Grout Injection (1)
- HAZID (1)
- HTLS (1)
- Hard impact (1)
- High-Rise Building (1)
- High-rise building (1)
- High-rise buildings (1)
- Horizontal stress (1)
- Horizontal wind turbine (1)
- Hydraulic jet erosion (1)
- IEPE (1)
- Impact damage of reinforced concrete (1)
- Impact damage on reinforced concrete (1)
- Impact loading (1)
- Impinging jet (1)
- Inclination angle (1)
- Inertial Interaction (1)
- Inertial interaction (1)
- Inhomogeneous soils (1)
- Inspeciton (1)
- Inspektion (1)
- Interface model (1)
- Jet impingement (1)
- Kinematic Interaction (1)
- Kinematic interaction (1)
- LBM-DEM coupling (1)
- LBM-DEM simulation (1)
- Laminar flow (1)
- Laminography (1)
- Large components (1)
- Lateral dynamic displacement (1)
- Lateral load bearing (1)
- Lattice Boltzmann Method (1)
- Lattice Boltzmann method (1)
- Load Test (1)
- Load bearing behaviour (1)
- Load identification (1)
- Load-bearing behaviour (1)
- Local approaches (1)
- Long-span bridge (1)
- Low-frequency shaker (1)
- Luminescence (1)
- MEMS (1)
- Maintal Bridge Gemuenden (1)
- Marine geomechanics (1)
- Marine geotechnics (1)
- Material Point Method (1)
- Material Point Method (MPM) (1)
- Material model (1)
- Measurement campaigns (1)
- Mechanical challenges (1)
- Microfine Cement (1)
- Microfine cement (1)
- Micromechanical LBM-DEM simulation (1)
- Micromechanical analysis (1)
- Micromechanical simulation (1)
- Microsilica (1)
- Mixed formulation (1)
- Modal analysis (1)
- Modal force spectrum (1)
- Modal load spectrum (1)
- Modal system identification (1)
- Modes (1)
- Modes and waves (1)
- Modulus of elasticity (1)
- Moisture (1)
- Monitoring-informed inspection and maintenance planning (1)
- Monopile Buckling (1)
- Monopile installation risks (1)
- Movin load test (1)
- Multi-beam method (1)
- Multi-beam track model (1)
- Multiple impact (1)
- NDT (1)
- Nelson’s method (1)
- Numerical analysis (1)
- Numerical damage simulation (1)
- Numerical simulation of impact damage (1)
- Numerical simulations (1)
- Obstacles (1)
- Offhore (1)
- Office building (1)
- Offshore Structures (1)
- Offshore Wind Energy Converter (1)
- Offshore pile foundation (1)
- Offshore pile foundations (1)
- Offshore steel structures (1)
- Offshore wind energy foundations (1)
- Offshore wind farm (1)
- Offshore wind farms (1)
- Offshore wind-turbine foundations (1)
- Operational modal analysis (1)
- Optimal sensor placement (1)
- Optimierungsmethoden (1)
- Optimization techniques (1)
- Perfectly Matched Layer (PML) (1)
- Physisoprtion (1)
- Piaui state (1)
- Pile Buckling (1)
- Pile Capacity (1)
- Pile Tip Buckling (1)
- Pile ageing (1)
- Pile bending stiffness (1)
- Pile foundation (1)
- Pile groups (1)
- Pile retrofit system (1)
- Pile-Tip-Buckling (1)
- Point Cloud (1)
- Predictive maintenance (1)
- Pressure (1)
- Probabilistic modelling (1)
- Probability of detection (1)
- Process noise (1)
- Propagation from a tunnel (1)
- Quasi-static response; (1)
- Rail roughness (1)
- Railbridge (1)
- Railway induced vibration (1)
- Railway track (1)
- Railway tracks (1)
- Railway trafiic (1)
- Random dynamics and vibrations (1)
- Random stiffness variation (1)
- Recovery experiments (1)
- Remote sensing vibrometer (1)
- Repowering (1)
- Residential building (1)
- Rigid vehicle model (1)
- Risk-based design (1)
- Risk-based maintenance planning (1)
- Road bridges (1)
- SHCC (1)
- SHM Environmental (1)
- SHM environmental bridges (1)
- Sandstone (1)
- Santa-marta (1)
- Scaling (1)
- Schwingungsmessungen (1)
- Schädigungsprozesse (1)
- Sensitivity vectors (1)
- Serra da cangalha (1)
- Shearing (1)
- Shell buckling (1)
- Shrinkage (1)
- Shrinkage Reducing Admixture (1)
- Simple and fast prediction (1)
- Simple prediction (1)
- Simulation and experiment (1)
- Site-characterization (1)
- Soft impact (1)
- Soft track elements (1)
- Soil forces (1)
- Soil stiffness (1)
- Soil-building interaction (1)
- Soil-building resonance (1)
- Soil-wall floor model (1)
- Soil-water-structure interaction (1)
- Sorption isotherm (1)
- Spatially varying ground conditions (1)
- Stability Buckling soil-structure-interaction piles offshore (1)
- State of stress (1)
- Static loading (1)
- Statistical correlations (1)
- Statistical pattern recognition (1)
- Stiffness variation (1)
- Strain (1)
- Strength (1)
- Stress stiffening (1)
- Stress-strain relation (1)
- Stress–strain-relation (1)
- Structural Systems (1)
- Structural integrity (1)
- Structural integrity maintenance (1)
- Structural integrity management (1)
- Substructures (1)
- Superplasticizer (1)
- Supplementary Cementitious Materials (1)
- Support structures (1)
- Surface Foundation (1)
- Surface line (1)
- Sustainable binders (1)
- Switch (1)
- TOP (1)
- TRC (1)
- Temperature effect (1)
- Temperature effect rejection (1)
- Temperature modeling (1)
- Tensile test (1)
- Test specification (1)
- Tip Buckling (1)
- Track and vehicle irregularities (1)
- Track beam (1)
- Track damage monitoring (1)
- Track damage quantification (1)
- Track deflection (1)
- Track displacements (1)
- Track filter (1)
- Track filtering (1)
- Track vibration (1)
- Tragstrukturen (1)
- Train configuration (1)
- Train passages (1)
- Train-induced vibration (1)
- Tran speed (1)
- Transfer fuction (1)
- Transfer function (1)
- Transverse butt weld (1)
- Trench (1)
- Truss structures (1)
- Tunnel (1)
- Tunnel line (1)
- Tunnel-pile transfer (1)
- Tunnel-to-surface reduction (1)
- Turnout (1)
- Un- certainty (1)
- Unbounded domain (1)
- Under-sleeper pads (1)
- Value of information (1)
- Variational Bayesian statistics (1)
- Varying soil stiffness (1)
- Varying stiffness (1)
- Varying track stiffness (1)
- Vibration analysis (1)
- Vibration excitation (1)
- Vibration monitoring (1)
- Viscosity (1)
- Water Science and Technology (1)
- Water-structure interaction (1)
- Wave-Tower interaction (1)
- Wavenumber domain (1)
- Wavenumber integrals (1)
- Wavenumber method (1)
- Waves (1)
- Weld imperfections (1)
- Welded (1)
- Wheelset (1)
- Wheelset accelerations (1)
- Wind Energy Structures (1)
- Wind energy tower (1)
- Wind turbines (1)
- Wind-farm aerodynamics (1)
- Windfarm wake analysis (1)
- Workability (1)
- Zuverlässigkeit (1)
- fachwerkartige Stahltragwerken (1)
- layered soil (1)
- risk, reliability, inspection planning, offshore wind turbines (1)
- temperature (1)
Organisationseinheit der BAM
- 7.2 Ingenieurbau (249) (entfernen)
Paper des Monats
- ja (4)
Grouting is a universal repair and strengthening technique, which is constantly used for structural remediation of concrete components, trenches, mine subsidence, dam joints, restoration of masonry structures, and geological stabilizations. Having an extremely small particle size of only few microns, ultrafine cements are ideal for grouting applications due to their superior permeability and compressive strength properties of the hardened cement paste compared to that of the less-expensive, but coarser ordinary Portland cements. Supplementary cementitious materials (SCMs) are often used to replace ultrafine cement in order to modify certain properties and to reduce costs. The aim of this experimental study is to investigate the effect of three supplementary materials: microsilica (MS), fly ash (FA), and metakaolin (MK) on the workability, and mechanical properties of an ultrafine cement based grout with a constant water-binder ratio and constant superplasticizer content. Maximum percentages of replacement with ultrafine cement were 6% by volume of cement for MS and 16% for FA, and MK. In general, results suggest that the workability is improved by addition of FA, whereas is reduced, when modified with MS and MK. The compressive strength of grout after cement replacement remains comparable to that of pure cement grout. However, there is a tendency of the MS to positively affect the compressive strength opposite to FA, whereas flexural strength is positively affected by FA. Based on the results, it is evident that grouts with Hägerman cone flow more than 500 mm and compressive strength of more than 90 MPa after 28 days can be produced.
Grouting is a universal repair and strengthening technique, which is constantly used for structural remediation of concrete components, trenches, mine subsidence, dam joints, restoration of masonry structures, and geological stabilizations. Having an extremely small particle size of only few microns, ultrafine cements are ideal for grouting applications due to their superior permeability and compressive strength properties of the hardened cement paste compared to that of the less-expensive, but coarser ordinary Portland cements. Supplementary cementitious materials (SCMs) are often used to replace ultrafine cement in order to modify certain properties and to reduce costs. The aim of this experimental study is to investigate the effect of three supplementary materials: microsilica (MS), fly ash (FA), and metakaolin (MK) on the workability, and mechanical properties of an ultrafine cement based grout with a constant water-binder ratio and constant superplasticizer content. Maximum percentages of replacement with ultrafine cement were 6% by volume of cement for MS and 16% for FA, and MK. In general, results suggest that the workability is improved by addition of FA, whereas is reduced, when modified with MS and MK. The compressive strength of grout after cement replacement remains comparable to that of pure cement grout. However, there is a tendency of the MS to positively affect the compressive strength opposite to FA, whereas flexural strength is positively affected by FA. Based on the results, it is evident that grouts with Hägerman cone flow more than 500 mm and compressive strength of more than 90 MPa after 28 days can be produced.
This talk provides a brief introduction on general engineering challenges for the offshore (marine) wind energy production, focusing on material, structural and hydromechanical aspects.
The talk begins with a broad overview on general trends for offshore wind-farms, with insights on some characteristic structural features and their associated loads. Then, some particular open issues for the foundation of the offshore wind turbines into the seabed are introduced. Here, different research approaches are discussed, from experimental investigations to coupled computational analysis at micro- and macroscopic scales.
In the second part of the seminar, both the hydromechanical Wave–Tower interaction and some general aspects of the windfarm aerodynamics (wake analysis) are discussed. Some modelling possibilities in the frame of CFD (computational fluid dynamics) are introduced and the relevance of such analyses for a proper windfarm layout optimization is pointed out.
Summing up, this seminar aims to show that: i) Numerical analysis of the turbine’s interaction with wind/waves and with the seabed is both useful and affordable. ii) Simplified models can provide an insight into windfarm aerodynamics. iii) Turbulent wake analysis is very relevant for the windfarm layout.
The Perfectly Matched Layer (PML) method is an efficient approach to imposing radiation conditions at the bounded region of interest in case of wave propagation in unbounded domains. This paper presents and validates 3D FE/PML numerical schemes based on two different PML formulations for homogeneous and inhomogeneous geological media exhibiting discrete or continuous inhomogeneity. In the equation of motion for the PML domain the applied stretching behavior is expressed either as complex material properties or as complex coordinates. Both PML formulations are implemented in the FEM and verified against analytical solutions. Three different types of material inhomogeneity are considered: layered half-space, continuously inhomogeneous half-space with linear velocity profile and continuously inhomogeneous half-space with nonlinear velocity profile. Sensitivity analyses are conducted, and the performance of the developed numerical schemes is investigated taking into account a broad variation of the PML parameters. Recommendations are given for the optimal values of the PML parameters for the case of homogeneous and inhomogeneous geological media.
The attenuation of wave amplitudes is ruled by the planar, cylindrical or spher-ical geometry of the wave front (the geometric or power-law attenuation) but also by the damping of the soil (an exponential attenuation). Several low- and high-frequency filter effects are derived for the layering and the damping of the soil, for the moving static and the distributed train loads and for a homoge-neous or randomly heterogeneous soil. Measurements of hammer- and train-induced vibrations at five sites have been analysed for these attenuation and filter effects. The measured attenuation with distance can be discribed by gen-eralised power laws and some reasons will be discussed. The theoretical filter effects can well be found in the measurements.
The attenuation of wave amplitudes is ruled by the planar, cylindrical or spherical geometry of the wave front (the geometric or power-law attenuation) but also by the damping of the soil (an exponential attenuation). Several low- and high-frequency filter effects are derived for the layering and the damping of the soil, for the moving static and the distributed train loads and for a homogeneous or randomly heterogeneous soil. Measurements of hammer- and train-induced vibrations at five sites have been analysed for these attenuation and filter effects. The measured attenuation with distance can be discribed by generalised power laws and some reasons will be discussed. The theoretical filter effects can well be found in the measurements.
Damage detection and localization in civil or mechanical structures is a subject of active development and research. A few vibration‐based methods have been developed so far, requiring, for example, modal parameter estimates in the reference and damaged states of the investigated structure, and for localization in addition a finite element model. For structures in operation, temperature has been shown to be a major nuisance to the efficiency of such methods because the modal parameters are varying not only with damage but also due to temperature variations. For detection, a few rejection approaches have been developed. Besides the increased complexity, environmental variation is hardly taken into account in localization approaches. In this paper, we propose a sensitivity‐based correction of the identified modal parameters in the damaged state with respect to the temperature field in the reference state, on the basis of a sensitivity analysis with respect to temperature dependent Parameters of the finite element model in the reference state. The approach is then applied to the stochastic dynamic damage locating vector method, where its improved performance under nonuniform temperature variations is shown in a numerical application on a beam.
The Bundesanstalt für Materialforschung und -prüfung (BAM) collaborates with TNO to develop a software framework for automated calibration of structural models based on monitoring data. The ultimate goal is to include such models in the asset management process of engineering structures. As a basis for developing the framework, a multi-span road bridge consisting of ten simply supported steel box girders was selected as a test case. Our group measured output-only vibration data from one box girder under ambient conditions. From the data, we determined eigenfrequencies and mode shapes. In parallel, we developed a preliminary structural model of the box girder for the purpose of predicting its modal properties. In this contribution, we provide an overview of the measurement campaign, the operational modal analysis, the structural modeling and qualitatively compare the identified with the predicted modes. As an outlook, we discuss the further steps in the calibration process and future applications of the calibrated model.
The Bundesanstalt für Materialforschung und -prüfung (BAM) collaborates with TNO to develop a software framework for automated calibration of structural models based on monitoring data. The ultimate goal is to include such models in the asset management process of engineering structures. As a basis for developing the framework, a multi-span road bridge consisting of ten simply supported steel box girders was selected as a test case. Our group measured output-only vibration data from one box girder under ambient conditions. From the data, we determined eigenfrequencies and mode shapes. In parallel, we developed a preliminary structural model of the box girder for the purpose of predicting its modal properties. In this contribution, we provide an overview of the measurement campaign, the operational modal analysis, the structural modeling and qualitatively compare the identified with the predicted modes. As an outlook, we discuss the further steps in the calibration process and future applications of the calibrated model.
Inspection and maintenance contribute significantly to the lifetime cost of bridges. There is significant potential in using information obtained through structural health monitoring to update predictive models of the condition and performance of such structures, and thus ena-ble an improved decision-making regarding inspection and maintenance activities. Within the AISTEC project funded by the German Federal Ministry of Education and Research, we develop vibration-based structural health monitoring systems aimed at continuously provid-ing information on the structural condition of bridges. Environmental variations such as changing ambient temperatures can significantly influence the dynamic characteristics of bridges and thus mask the effect of structural changes and damages. It remains a challenge to account for such influences in structural health monitoring. To study the effect of ambient temperatures on the dynamic characteristics of beam structures, we monitor the vibration response of a reinforced concrete beam in the uncracked and cracked state at varying tem-peratures in a climate chamber. We postulate a set of competing parameterized probabilistic structural models, which explicitly account for the effect of varying ambient temperatures on the mechanical properties of the system. We then combine the information provided by the structural models with the information contained in the recorded vibration data to learn the parameters of the temperature-dependent structural models and infer the plausible state of the beam using Bayesian system identification and model class selection.
Inspection and maintenance contribute significantly to the lifetime cost of bridges. There is significant potential in using information obtained through structural health monitoring to update predictive models of the condition and performance of such structures, and thus ena-ble an improved decision-making regarding inspection and maintenance activities. Within the AISTEC project funded by the German Federal Ministry of Education and Research, we develop vibration-based structural health monitoring systems aimed at continuously provid-ing information on the structural condition of bridges. Environmental variations such as changing ambient temperatures can significantly influence the dynamic characteristics of bridges and thus mask the effect of structural changes and damages. It remains a challenge to account for such influences in structural health monitoring. To study the effect of ambient temperatures on the dynamic characteristics of beam structures, we monitor the vibration response of a reinforced concrete beam in the uncracked and cracked state at varying tem-peratures in a climate chamber. We postulate a set of competing parameterized probabilistic structural models, which explicitly account for the effect of varying ambient temperatures on the mechanical properties of the system. We then combine the information provided by the structural models with the information contained in the recorded vibration data to learn the parameters of the temperature-dependent structural models and infer the plausible state of the beam using Bayesian system identification and model class selection.
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.
This contribution presents experimental methods to detect track damage. At BAM (Federal Institute of Material Research and Testing), a measuring car with a measuring system of 72 channels, geophones, mountings, cables, harmonic and impulsive exciters is used for dynamic measurements of the track, the soil and buildings. An instrumented hammer allows force measurements and to evaluate transfer functions of the track, and the soil. Wave measurements are used to identify the soil characteristics. Train passages are measured at the track and for the train induced ground vibrations. In addition to these in situ options, tests of tracks or track elements can be performed in a large laboratory.
There is a strong need for cost-effective mitigation measures for
turnouts. SBB has initiated a series of examinations using different methodologies to gain a deeper understanding of the excitation mechanisms at low frequencies, in addition to that obtained in the RIVAS project. To date it is not yet clear what constitutes a complete measurement data set that would enable understanding most of the vibration excitation mechanisms in turnouts. Increasing vibration at turnouts in comparison to normal track is observed for all measured frequencies.
The different methodologies are presented in the paper. Under-sleeper pads (USP) are a cost-effective method to reduce vibration at frequencies above 63 Hz (1/3 octave), but there is probably no improvement for frequencies below 63 Hz. A first test of new frog geometry did not show relevant improvements in Vibration emission in comparison to a reference frog geometry. Axle box acceleration measurements are an interesting method to identify defects in a turnout. A specialized measurement system of rail roughness could identify certain geometry Problem areas for some frogs. Noise increases also are observed at turnouts for frequencies ranging between 80 to 1000 Hz. The use of railway source models to calculate
contact forces for ballasted track and turnouts seems promising, in particular for understanding the influence of ground.
The identification of the dynamic behavior of structures, like bridges and towers, is relevant to address multiple issues. In many cases the dynamic parameters should be acquired only once or at a frequency that doesn’t justify the installation of distinct vibration sensors for a long-term monitoring. To identify modal frequencies of a structure, a drone based mobile sensing platform has been implemented. This sensing platform measures the relative displacement be-tween the structure and the drone, which also shows a strong dynamic behavior under wind tur-bulences. By regarding the dynamic model of the drone and additional measurements at the dis-tance sensor the absolute movement of the structure can be estimated based on the measured relative distance. This time domain data is a suitable input for various operational modal analysis algorithms. The system has been used to identify the dynamic properties of test and real structure, like a 1.5 MW wind turbine tower.
The identification of the dynamic behavior of structures, like bridges and towers, is relevant to address multiple issues. In many cases the dynamic parameters should be acquired only once or at a frequency that doesn’t justify the installation of distinct vibration sensors for a long-term monitoring. To identify modal frequencies of a structure, a drone based mobile sensing platform has been implemented. This sensing platform measures the relative displacement be-tween the structure and the drone, which also shows a strong dynamic behavior under wind tur-bulences. By regarding the dynamic model of the drone and additional measurements at the dis-tance sensor the absolute movement of the structure can be estimated based on the measured relative distance. This time domain data is a suitable input for various operational modal analysis algorithms. The system has been used to identify the dynamic properties of test and real structure, like a 1.5 MW wind turbine tower.
This article deals with two topics of vehicle-track-soil interaction, the mitigation of railway induced ground vibration by soft track elements, and the identification of track damage. Theoretical results have been achieved by a combined finite-element boundary-element method (FEBEM). The theoretical results are confronted with measurements at four sites. Improved mitigation effects have been found for soft rail pads under heavy sleepers. The insertion loss, however, can be too optimistic if a strong vehicle track resonance occurs for the un-isolated reference track. Two measurement sites show this strong vehicle-track resonance at about 80 Hz, which has been approximated by using the results of a wide parameter study including the rail pad, ballast, and soil stiffness, as well as the ballast model and the soil layering. – The detection of slab track damage is mainly based on the differences of the receptance or compliance functions. Theoretical results have been confirmed by measurements at one site where a loss of contact between track plate and base layer was visible. Measurements at a second site with a hidden damage have been compared with the theoretical results of a loose sleeper. The differences between intact (or repaired) and damaged tracks are strong enough to encourage the further development of this method for the identification of track damages.
Abstract. Three measurement campaigns of train-induced ground vibrations are evaluated for the vehicle-track-soil interaction. Ground vibrations, track vibrations and vehicle vibrations have been measured for train passages and impulse excitation and compared with theoretical results.
The soil and the track-soil system are calculated by wavenumber integrals. The influence of the vehicle is introduced by a substructure method. By comparing theory and measurement the different components of excitation force and ground vibration can be analysed, the quasi-static excitation, track-alignment errors, the out-of-roundness of wheels, the wheel and rail roughness, and moreover, scattered axle impulses and ineffective high-frequency parts of the wheelset accelerations and forces.
Three measurement campaigns of train-induced ground vibrations are evaluated for the vehicle-track-soil interaction. Ground vibrations, track vibrations and vehicle vibrations have been measured for train passages and impulse excitation and compared with theoretical results. The soil and the track-soil system are calculated by wavenumber integrals. The influence of the vehicle is introduced by a substructure method. By comparing theory and measurement the different components of excitation force and ground vibration can be analysed, the quasi-static excitation, track-alignment errors, the out-of-roundness of wheels, the wheel and rail roughness, and moreover, scattered axle impulses and ineffective high-frequency parts of the wheelset accelerations and Forces.