7.2 Ingenieurbau
Filtern
Dokumenttyp
- Beitrag zu einem Tagungsband (13)
- Vortrag (9)
- Zeitschriftenartikel (1)
- Posterpräsentation (1)
Sprache
- Englisch (24) (entfernen)
Referierte Publikation
- nein (24) (entfernen)
Schlagworte
- Offshore (4)
- Structural health monitoring (3)
- Grout (2)
- Monopiles (2)
- Repair (2)
- Structural Health Monitoring (2)
- Analysis of variance (1)
- Artificial intelligence (1)
- BIM (1)
- Bayesian System Identification (1)
- Bayesian methods (1)
- Bayesian updating (1)
- Box-Behnken (1)
- Buckling (1)
- Buckling piles circular shells (1)
- Compaction Grouting (1)
- Crack formation (1)
- Crack pattern (1)
- Cracks (1)
- Cyclic load (1)
- Digital Models (1)
- Digital twin (1)
- Drop Tests (1)
- End-of-life decision making (1)
- Energy (1)
- Environmental (1)
- Environmental effects (1)
- Fly ash (1)
- Foundation reliability analysis (1)
- Foundations (1)
- Grout Injection (1)
- Grouted Connection (1)
- Grouted connection (1)
- Grouting (1)
- Injection Sequence (1)
- Interface (1)
- Long-term shrinkage (1)
- Marine geomechanics (1)
- Material tests (1)
- Metakaolin (1)
- Micro silica (1)
- Monopile Buckling (1)
- Monopile installation risks (1)
- Numerical modelling (1)
- Numerical simulations (1)
- Offshore Pile Foundation (1)
- Offshore Wind Energy (1)
- Offshore Wind Energy Converter (1)
- Offshore foundations (1)
- Offshore wind (1)
- Offshore wind energy (1)
- Optimal Sensor Placement (1)
- Pile Buckling (1)
- Pile Capacity (1)
- Pile Foundation (1)
- Pile Tip Buckling (1)
- Pile-Tip-Buckling (1)
- Probabilistic modelling (1)
- Rehabilitation (1)
- Repowering (1)
- Research data management (1)
- SHM (1)
- SHM Environmental (1)
- Shearing (1)
- Shell Buckling (1)
- Soil-Structure-Interaction (1)
- Soil-pile interaction (1)
- Soil-structure interaction (1)
- Spatially varying ground conditions (1)
- Stability Buckling soil-structure-interaction piles offshore (1)
- Static load (1)
- Substructures (1)
- Supplementary cementitious materials (1)
- System Identification (1)
- TOP (1)
- Tensile Capacity (1)
- Tip Buckling (1)
- Value of Information (1)
- Wind (1)
- Wind Energy (1)
- Wind Energy Structures (1)
- Windenergy (1)
Organisationseinheit der BAM
- 7.2 Ingenieurbau (24) (entfernen)
Eingeladener Vortrag
- nein (9)
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.
At the Bundesanstalt für Materialforschung und -prüfung (BAM) full scale specimens for nuclear transport and storage containers (casks) are tested for their structural integrity in a series of drop tests on the Test Site Technical Safety in Horstwalde, 50 km south of Berlin. These drop tests cause a major stress not only on the casks, but also on the steel tower structure of the test facility, itself. The load pattern makes the structure very interesting for detailed investigation. The focus of the monitoring lies on the bolted joints of the flange connections that are a typical connection for cylindrical elements if welding is technical or economical unfavorable. The definition of the monitoring takes was done by investigating the existing documents and inspection results accompanied by building an initial digital representation of the structure, consisting of two finite element (FE) models and a geometrical 3D point cloud representation. As a first step the structures behavior during static and dynamic loading was analyzed using measurement data and an updated numerical FE Model. The idea behind is to use models for a digital planning and operation/evaluation of the structural health monitoring. A static FE simulation and a dynamic FE simulation are generated, to investigate how the structure behaves under the load conditions.
Global energy consumption will increase in the future necessitating both fossil fuels and renewable energy choices - especially wind energy. Such high energy demand requires installation of offshore energy structures, rigs, platforms and towers, which are susceptible to adverse environmental conditions along with maintenances. Due to their large size and remote locations, cylindrical grouted joints are often adopted between substructure and foundation in these offshore platforms and wind structures such as monopiles. However, these connections are composite structures with exterior sleeve, interior pile and infill mortar. Degradation and settlements were reported inside similar connections, which were installed in last three decades. Besides, grouting in the offshore sites were proven difficult to obtain ideal load bearing capacity. In-situ loading conditions were also found to be affecting the failure mechanism inside such connections. This study aims at characterizing the nature of cracks generated in these grouted connections under both static and cyclic loading. Scaled grouted joints were manufactured using a novel reusable mold, and connections were loaded to failure to visualize the main failure patterns. An assessment between failure under these two types of load is drawn along with comparison to previously available literature.
The structural performance of many geotechnical systems (e.g. axially-loaded pile foundations), depends on the shearing resistance at the soil interface, which may govern the load bearing capacity of the foundation. Experimental investigations have shown that this interaction is mainly localised within a narrow shear band next to the structure. Under cyclic loading, a contraction of the soil at the interface may arise (net volume loss), possibly leading to a stress relaxation and thus to a reduction of the load bearing capacity (the so-called friction fatigue). Based on the constitutive similarities between soil continua and interfaces, we propose here the adaption of a Generalized Plasticity model for sandy soils for the numerical analysis of interface problems. In this contribution, the results of an experimental campaign for the parameter calibration of the constitutive model are presented. The tests have been conducted with a ring shear device involving different normal stresses, roughness of the steel plates as well as cyclic loading. The new modelling approach shows promising results and has the additional practical advantage that the interface zone and the soil continuum can both be described with the same constitutive model in general boundary value problems.
The aim of an ongoing research project is to develop a design approach for typical offshore driven piles (e.g. Jacket piles) based on the application of injections by compaction grouting directly at the pile shaft. The paper aims to present the results of laboratory and in-situ tests, which reveal the efficiency and the promising potential of the optimised foundation concept for a more economic dimensioning of pile foundations and to increase their bearing capacity in non-cohesive soil at any moment after installation.
Grouts have numerous applications in construction industry such as joint sealing, structural repair, and connections in precast elements. They are particularly favoured in rehabilitation of structures due to penetrability and convenience of application. Grouts for repair applications typically require high-performance properties such as rapid strength development and superior shrinkage characteristics. Sometimes industrial by-products referred as supplementary cementitious materials (SCM) are used with neat cement due to their capabilities to provide binding properties at delayed stage. Micro silica, fly ash and metakaolin are such SCMs, those can modify and improve properties of cement products. This study aims at investigating long-term mass loss and linear shrinkage along with long-term compressive and flexural strength for grouts produced from ultrafine cement and SCMs. A series of mixtures were formulated to observe the effect of SCMs on these grout properties. Properties were determined after 365 days of curing at 23oC and 55% relative humidity. The effect of SCMs on the properties are characterised by statistical models. Response surfaces were constructed to quantify these properties in relation to SCMs replacement. The results suggested that shrinkage was reduced by metakaolin, while micro silica and fly ash had positive effects on compressive and flexural strength, respectively.
Remediation of Cracks Formed in Grouted Connections of Offshore Energy Structures under Static Loads
(2018)
The future energy demand necessitates the exploration of all potential energy sources both onshore and offshore. Global trend has shifted towards offshore energy, which can be obtained from either carbon intensive or renewable options, hence requiring structures such as rigs, platforms, and monopiles. Most of these structures adopt easily installable construction techniques, where lower foundation need to be connected with the super structure by mean of grouted composite joints. Generally, these composite connections have exterior sleeve, interior pile and infill grout. Being located in remote offshore conditions, connections can experience considerable adverse loading during their lifetimes. Degradations were reported inside similar connections, which were installed in last three decades. Besides, grouting in the offshore sites may often be proven difficult, which eventually leads to reduced capacity of connections in the long run. Thus, repair and rehabilitation of such connections should be planned ahead to minimize operational delays and costs in the future. This study aims at characterizing the nature of crack generation in grouted connections and thereby identifying the potential of repair using suitable repair material. Scaled grouted joints were manufactured using a novel mold, and connections were loaded under static load to visualize the main failure pattern. The failure mechanism and loading capacity are found compatible to previous results from earlier literature. Grouted connection was then repaired using cementitious injectable grout. The effectiveness of the repair system is also discussed.