@misc{MarkerJirasekSchmidtetal., author = {Marker, Paul and Jirasek, Robert and Schmidt, Therese and Bleicher, Achim}, title = {Development, realization, and experimental validation of an active hybrid roof structure based on elastic kinetic and rigid-body transformation}, series = {International Journal of Space Structures}, volume = {38 (2023)}, journal = {International Journal of Space Structures}, number = {2}, issn = {2059-8033}, doi = {10.1177/09560599221134286}, pages = {83 -- 100}, abstract = {Elastic kinetic structures are a recent approach to design transformable structures. Their transformation is based on elastic bending, that is compliant component behavior of structural members. This principle can be used to realize transformable structures with a stable deployment process. Regardless of a stable transformation, elastic kinetic structures are prone to static and dynamic loads due to their lightweight design. However, most of current research on these structures solely focuses on the principles of transformation. This paper proposes a concept for an active hybrid roof structure with a transformation based on elastic kinetics and rigid-body motion. The concept exhibits a stable structural deployment and active control components to counteract static and dynamic disturbances. Furthermore, this paper includes the realization and experimental evaluation of a mid-scale prototype structure.}, language = {en} } @misc{ZhangWulffWernickeetal., author = {Zhang, Yangwen and Wulff, Wulf and Wernicke, Laurenz and Engelmann, Michael and Schauer, Thomas and Bleicher, Achim}, title = {Experimental identification and verification of a moveable facade element for energy harvesting and vibration control}, series = {Journal of Building Engineering}, volume = {65}, journal = {Journal of Building Engineering}, issn = {2352-7102}, doi = {10.1016/j.jobe.2022.105712}, abstract = {The distributed-Multiple Tuned Facade Damping (d-MTFD) system was proposed to effectively reduce wind-induced vibrations of high-rise buildings by using the parallel moveable outer skin of the Double-Skin Facade (DSF) as damping mass. A full-scale prototype with a moveable (kinetic) DSF element has been built for first experimental tests using Hardware-in-the-Loop (HiL) simulations. The parallel moveability of the DSF's outer skin is achieved by mounting it on a smooth-running guide rail system. A stepper motor is applied as an adjustable electrical damper and simultaneously serves as an energy harvester. By using grey-box system identification, all the parameters of the prototype can be accurately estimated. For example, a low equivalent friction ratio of 0.0022 was estimated. The identified model achieved high fitness values (80\% to 91\%) compared to the measured data, providing the basis for the reliability of the experimental tests using HiL. The prototype is the hardware part of the HiL simulations, which is connected to the simulation part, namely, a 76-story, 306 m high benchmark building assumed to be installed with the d-MTFD system. The feasibility of using a stepper motor as an adjustable electrical damper for semi-active control has been successfully validated based on the HiL simulations. By using semi-active control, the relative displacement of the DSF's outer skin can be significantly reduced by about 35\% compared with using passive control. Energy harvesting performance has also been investigated. The average energy harvesting efficiency of the power electronics was experimentally determined as approximately 75\%. With consideration of all the parasitic damping in the connection, the average energy harvesting efficiency was about 50\%. For tests under across-wind excitation with a return period of 10 years, the self-sufficient operation of the semi-active d-MTFD system was proven to be achievable based on the prototype results. The average harvested power of the whole benchmark building (with 1000 moveable facade elements) can be predicted as 1.3 kW.}, language = {en} } @misc{JirasekSchauerBleicher, author = {Jirasek, Robert and Schauer, Thomas and Bleicher, Achim}, title = {Linear parameter-varying output-feedback for active vibration control of an elastic kinetic roof structure with experimental validation}, series = {Engineering Structures}, volume = {307}, journal = {Engineering Structures}, issn = {0141-0296}, doi = {10.1016/j.engstruct.2024.117887}, pages = {1 -- 12}, abstract = {Elastic kinetics are an approach to design transformable lightweight structures with a stable transformation process. The transformation is realized through elastic bending of structural members by exploiting the compliant material behavior. This lightweight and flexible design comes at the cost of increased sensitivity to static and dynamic disturbances. However, most of the current research focuses on the principles of elastic kinetic transformation instead of effective disturbance mitigation. This work focuses on dynamic disturbance mitigation for such transformable lightweight structures using active control. Modeling and controller synthesis are performed in the linear parameter-varying (LPV) framework, since the dynamics of elastic kinetic structures are transformation-state dependent due to geometric nonlinearities. Based on an LPV model in a grid-based representation, an LPV output-feedback control can be designed and synthesized via a gridding approach. This methodology is experimentally tested and validated for the example of an active hybrid roof structure prototype.}, language = {en} } @misc{OPUS4-33638, title = {Ressourcen- und energieeffiziente Konstruktionen : 28. Brandenburgischer Bauingenieurtag BBIT 2024}, number = {Heft 16}, editor = {Bleicher, Achim}, publisher = {BTU Cottbus-Senftenberg}, address = {Cottbus}, isbn = {978-3-940471-77-2}, issn = {2569-2798}, doi = {10.26127/BTUOpen-6689}, pages = {1 -- 116}, abstract = {Der 28. Brandenburgische Bauingenieurtag 2024 an der BTU Cottbus-Senftenberg widmet sich den angestrebten Zielen einer Ressourcen- und Klimaneutralit{\"a}t. M{\"o}glich wird dies durch innovative Ans{\"a}tze und interdisziplin{\"a}re Planungs-, Bau- und Betriebsprozesse. Die Referenten zeigen Herausforderungen und L{\"o}sungen bei der Entwicklung klimaneutraler Baustoffe und Bauteile sowie deren Weiterverwendung und Kreislauff{\"a}higkeit. Dar{\"u}ber hinaus werden Erkenntnisse zur Ert{\"u}chtigung und Erhaltung vorhandener Bausubstanz sowie zu leichten, hybriden und adaptiven Konstruktionsans{\"a}tzen vorgestellt.}, language = {de} } @techreport{HoeltkeManfrecolaBleicher, author = {H{\"o}ltke, Tim and Manfrecola, Johannes and Bleicher, Achim}, title = {Biegetragf{\"a}hige Holz-Beton-Verbundknoten aus Baubuche zur Aussteifung von Hochbauten}, volume = {78/2024}, address = {Bonn}, issn = {1868-0097}, pages = {85}, abstract = {Das hier bearbeitete Forschungsprojekt leistet einen ersten Beitrag zur Entwicklung von biegetragf{\"a}higen Holz-Beton-Verbundknoten in Rahmentragwerken zur Aussteifung von Hochbauten. Rahmentragwerke liefern architektonische Vorteile in der Grundriss- und Fassadengestaltung von Geb{\"a}uden durch den Wegfall von aussteifenden Verb{\"a}nden und Schubw{\"a}nden und sind damit besonders f{\"u}r eine sp{\"a}tere Umnutzung geeignet. Die Entwicklung der hier betrachteten Rahmenknoten basiert auf dem Lastabtrag mehrfeldriger und mehrgeschossiger ebener Rahmensysteme. Der lokale Lastabtrag in der Knotenkonstruktion konnte im ersten Schritt des Projektes auf Grundlage von Stabwerksmodellen visualisiert und nachgewiesen werden. Es wurde darauf geachtet, die verwendeten Materialien - Holz, Beton und Stahl - werkstoffgerecht einzusetzen, um eine gr{\"o}ßtm{\"o}gliche Tragf{\"a}higkeit zu erzielen. Rahmentragwerke gelten aufgrund der konzentrierten Lastabtragung in den Knoten als hochbeanspruchte Tragwerke. Daher wurde ein hochfestes Buchenfurnierschichtholz der Firma Pollmeier Furnierschichtholz GmbH verwendet, welches eine etwa 3-mal h{\"o}here Biegefestigkeit als konventionelle Nadelh{\"o}lzer aufweist. Zur Untersuchung der statischen Eigenschaften wie Lastabtragungsmechanismen, Grenztragf{\"a}higkeiten und Rotationssteifigkeiten wurde eine Versuchsserie mit insgesamt 6 Versuchsk{\"o}rpern im realit{\"a}tsnahen Maßstab erarbeitet. Die einzelnen Versuchsk{\"o}rper unterscheiden sich in den geometrischen Abmessungen der Riegelquerschnitte, im St{\"u}tzenanschluss und der Festigkeit des Verbundpartners Beton. Zur besseren Vergleichbarkeit wurden die Betone in der Forschungs- und Materialpr{\"u}fanstalt (FMPA) der BTU Cottbus-Senftenberg selbst hergestellt, mit dem Ziel vergleichbare Werkstoffeigenschaften zwischen den einzelnen Versuchsk{\"o}rpern zu erzielen bei denen der Beton nicht der Variationsparameter ist. Im Sinne einer nachhaltigen Kreislaufwirtschaft wurde auch untersucht, ob sich Recyclingbeton f{\"u}r die statischen Anforderungen in der Rahmenkonstruktion eignet. Die einzelnen Versuchsk{\"o}rper wurden zum weiteren Erkenntnisgewinn numerisch mit Hilfe der FE-Software Ansys Workbench untersucht. In den r{\"a}umlichen Modellen wurden, f{\"u}r m{\"o}glichst realit{\"a}tsnahe Simulationen der experimentellen Versuche, die materiellen und kontaktbedingten Nichtlinearit{\"a}ten ber{\"u}cksichtigt. Die numerischen Ergebnisse wurden anschließend anhand der experimentellen Ergebnisse validiert. Die Herstellung der Versuchsk{\"o}rper und die experimentelle Versuchsdurchf{\"u}hrung erfolgte in der FMPA. Auf Basis der numerischen und experimentellen Erkenntnisse konnten anschließend maßgebende Versagensstellen identifiziert und ein analytisches Konzept zur Bestimmung der Tragf{\"a}higkeit erarbeitet werden. Auch wurden signifikante Verformungskomponenten benannt und zu einem analytischen Gesamtfedermodell der Knotenkonstruktion nach Vorbild der Komponentenmethode aus dem Stahl- und Stahl-Beton-Verbundbau zusammengef{\"u}hrt. Durch ein erstes Gesamtfedermodell kann aus den Verformungen der Komponenten die Rotationssteifigkeit berechnet werden. Das analytische Gesamtfedermodell wurden abschließend mit den experimentellen Ergebnissen validiert. Den Abschluss des Forschungsprojektes bilden Empfehlungen zur Ausbildung duktiler Rahmenknoten im Holz-Beton-Verbundbau auf Grundlage der experimentellen, numerischen und analytischen Ergebnisse.}, language = {de} } @techreport{SchauerBleicherZhangetal., author = {Schauer, Thomas and Bleicher, Achim and Zhang, Yangwen and Wulff, Wulf and Wernicke, Laurenz}, title = {Schwingungsd{\"a}mpfung und Energiegewinnung mit beweglichen Doppelfassaden: Entwurf Optimierung und Validierung eines autarken verteilten semiaktiven Systems zur Reduktion Wind-induzierter Schwingungen bei schlanken Hochh{\"a}usern}, volume = {08/2022}, address = {Bonn}, issn = {1868-0097}, url = {http://nbn-resolving.de/urn:nbn:de:101:1-2022112808245531150998}, pages = {98}, abstract = {Weltweit werden immer mehr „superschlanke" Hochh{\"a}user gebaut, da sie bei einer dichten st{\"a}dtischen Fl{\"a}chennutzung erhebliche wirtschaftliche Vorteile bieten. Jedoch sind sie sehr anf{\"a}llig f{\"u}r Windanregungen. Schwingungstilger sind passiv als auch aktiv Stand der Technik und haben sich als effiziente L{\"o}sungen zur D{\"a}mpfung Wind-induzierter Strukturschwingungen erwiesen. Dieser Ansatz ben{\"o}tigt jedoch zus{\"a}tzliche Masse und einen großen Bauraum in den begehrten obersten Etagen. In diesem Forschungsprojekt wurde ein neuer semiaktiver und verteilter Fassadend{\"a}mpfer untersucht, der die Masse der Außenhaut einer Doppelfassade im Sinne der Ressourceneffizienz als D{\"a}mpfungsmasse nutzt. F{\"u}r die Realisierung einer zeitlich ver{\"a}nderlichen D{\"a}mpfung wurde ein mechatronischer Schwingungsd{\"a}mpfer inklusive Energie-Harvester entwickelt, der Energie in einer Batterie speichert. Zur Validierung der Konzepte und zum Nachweis des autarken Betriebs des geregelten D{\"a}mpfungssystems wurde in Zusammenarbeit mit der Josef Gartner GmbH ein bewegliches Doppelfassadenelement als Prototyp realisiert und auf einem Versuchsstand installiert. Dies erlaubt die Durchf{\"u}hrung von Hardware-in-the-Loop Simulationen, bei denen ein gesamtes Geb{\"a}ude simuliert wird und ein einzelnes Fassadenelement als Hardware physisch aktiv ist und sein Verhalten untersucht werden kann. Die Machbarkeit einer autarken semiaktiven D{\"a}mpfung mit parallel beweglichen Prallscheiben an Doppelfassaden konnte somit erfolgreich demonstriert werden. Der Ansatz liefert einen Beitrag, den CO2-Fußabdruck eines Hochhauses zu reduzieren.}, language = {de} } @phdthesis{Jirasek, author = {Jirasek, Robert}, title = {The linear parameter-varying framework for active vibration control of elastic kinetic structures}, publisher = {BTU Cottbus-Senftenberg}, address = {Cottbus}, doi = {10.26127/BTUOpen-6769}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-67698}, pages = {141}, abstract = {Lightweight design is essential for preserving resources, and in addition, transformability can be beneficial for specific applications where multi-functionality is required. Multi-functionality contributes to saving resources by allowing multiple purposes to be served effectively and by allowing adaptation to changing needs. Elastic kinetics are a recent approach to design transformable lightweight structures with a stable transformation process, realized by elastic bending of structural members. Their lightweight and flexible design comes at the cost of increased sensitivity to static and dynamic disturbances. However, most of the current research concentrates on transformation principles instead of on disturbance mitigation. This research focuses on dynamic disturbance mitigation for transformable lightweight structures based on elastic kinetics using active control. The dynamic behavior of such structures is transformation state dependent due to geometric nonlinearities, which is not easily captured by linear time-invariant methods. For this reason, modeling and control design are performed in the linear parameter-varying (LPV) framework. Thereby, two distinct LPV modeling methodologies are investigated, one based on finite element models and another utilizing experimental system identification techniques. Furthermore, LPV control strategies are introduced, which allow to adapt to the varying structural dynamics encountered in elastic kinetics. To validate the efficacy of the modeling and control approaches, a physical demonstrator resembling a segment of an elastic kinetic roof structure is realized within a laboratory environment. This demonstrator structure is used for experimental studies to assess the accuracy and performance of the introduced methods. Utilizing experimental data from the demonstrator structure, a proposed LPV system identification methodology can be applied to derive separate LPV models for the bending and the torsional dynamics of the demonstrator structure. Based on the derived LPV models, a decoupled active vibration control for bending and torsional dynamics by means of an LPV output-feedback is designed. The designed control is implemented on a real-time environment, and its effectiveness is demonstrated experimentally for fixed and for varying operating conditions on the realized demonstrator structure.}, language = {en} } @misc{ZhangWernickeWulffetal., author = {Zhang, Yangwen and Wernicke, Laurenz and Wulff, Wulf and Bleicher, Achim and Schauer, Thomas}, title = {Design and validation of a dual-functional damper based on a stepper motor for energy harvesting and vibration control}, series = {Mechanical Systems and Signal Processing}, volume = {200}, journal = {Mechanical Systems and Signal Processing}, number = {110568}, issn = {0888-3270}, doi = {10.1016/j.ymssp.2023.110568}, pages = {1 -- 19}, abstract = {Dampers are widely used to reduce undesired vibrations. In recent decades, they have been developed from the energy dissipation strategy to the energy harvesting strategy. Dual-functional dampers, which convert part of vibration energy into electrical energy, are intensively studied. DC motors are the most applied electromagnetic transducers in these studies. In this paper, two-phase stepper motors are applied as adjustable electrical dampers and energy harvesters. Dual-functional dampers using stepper motors inherently have higher damping density than those using DC motors, as stepper motors have more pole pairs than DC motors. The nonlinear theoretical electrical damping coefficient of two-phase stepper motors is derived and compared with that of DC motors. A dual two-stage Energy Harvesting Circuit (EHC) is proposed to realize the function of adjustable electrical damping through resistance emulation and the function of harvesting energy. A test bench is built to experimentally verify the adjustable electrical damping and energy harvesting performance of a selected two-phase hybrid stepper motor with the proposed dual two-stage energy harvesting circuit. The numerical solution from the identified model shows a high agreement with the experimental results. The energy harvesting efficiency in the electrical domain has reached about 85\%. This tested dual-functional damper using a stepper motor has been successfully integrated into a full-scale demonstrator of the distributed-Multiple Tuned Facade Damping (d-MTFD) system.}, language = {en} } @phdthesis{Zhang, author = {Zhang, Yangwen}, title = {Self-sufficient semi-active vibration control of high-rise buildings under wind excitation by moveable double-skin facades}, address = {Cottbus ; Senftenberg}, issn = {2569-2798}, doi = {10.26127/BTUOpen-6381}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-63811}, pages = {184}, abstract = {The accelerated urbanization has led to increasing tension on urban land use. In this context, more and more slender high-rise buildings are being built worldwide in pursuit of better economic benefits. However, these structures are susceptible to wind excitation due to their lower first natural frequency. Different passive, semi-active, and active damping systems have been developed to reduce wind-induced structural vibration. Among them, the tuned mass dampers are widely used and proved as a very effective method in practice. However, this system requires a large additional damping mass. This also causes additional reinforcement, which increases the cost and carbon footprint. A huge space near the top story of the building is needed for the installation. In this research, a novel system named distributed-Multiple Tuned Facade Damping (d-MTFD) system is proposed by using specially designed parallel moveable Double-Skin Facade (DSF) outer skin as damping mass. These moveable facade elements can be installed on the upper stories of the high-rise building. Smooth-running guide rail systems are used to achieve the parallel moveability. Multi-objective optimization based on the Genetic Algorithm (GA) is applied to reduce the maximum top floor acceleration (Objective I) and to reduce the maximum facade relative displacement (Objective II) simultaneously. The optimization results for the passive and semi-active systems are presented in the form of the Pareto front. The trade-off between these selected two competing optimization objectives is observed. This approach was first validated in a simulation using a 306 m tall reference building for a wind speed of 13.5 m/s at 10 m above ground level with a return period of 10 years. Acceptable peak accelerations at the top story for hotel use and a maximum facade relative displacement of less than ±0.5 m could be achieved for the benchmark building with the d-MTFD system. For semi-active control, the variable damping coefficient can be achieved by using stepper motors in generator mode. The electrical damping coefficient can be continuously adjusted by the developed power electronics. In addition, electrical energy can be generated and stored in a battery. A full-scale prototype with one parallel moveable facade element was built. Based on the prototype, the functionality of the semi-active control using a stepper motor and its energy harvesting performance was tested by applying Hardware-in-the-Loop (HiL) simulations. Greybox system identification was used to estimate some parameters (spring stiffness, friction, etc.) in the connection. The accurate system identification results ensure further validation using HiL simulations. The HiL simulations successfully demonstrated the feasibility of a self-powered semi-active d-MTFD system.}, language = {en} } @misc{BleicherHoeltkeManfrecola, author = {Bleicher, Achim and H{\"o}ltke, Tim and Manfrecola, Johannes}, title = {Hybrid structures for tall buildings with hardwood LVL and concrete}, series = {IABSE Symposium 2025, Environmentally Friendly Technologies and Structures - Focusing on Sustainable Approaches, May 18-21, 2025, Tokyo, Japan}, journal = {IABSE Symposium 2025, Environmentally Friendly Technologies and Structures - Focusing on Sustainable Approaches, May 18-21, 2025, Tokyo, Japan}, publisher = {International Association For Bridge And Structural Engineering (IABSE)}, address = {Z{\"u}rich}, isbn = {978-3-85748-206-9}, doi = {10.2749/tokyo.2025.1927}, pages = {1927 -- 1934}, abstract = {New fire design approaches enable innovative load-bearing and bracing concepts for tall buildings made of timber. As a renewable building material, timber in combination with concrete is currently setting new heights and at the same time offers a high CO2 saving potential. Usually, timber-concrete composite structures are mainly used in the floor slabs to ensure sound insulation and fire protection. This paper presents a newly developed beam-to-column joint for timber-concrete composite frames, which has been studied in terms of its ability to transfer bending moments, normal and shear forces. A series of full-scale experimental tests were conducted to investigate the structural properties of the joint design. In addition, all specimens were analysed numerically to verify the load transfer mechanisms. As an overall result, the test specimens showed a ductile behaviour beyond their primary failure. Finally, hybrid multi-story frame systems with rigid beam-to-column connections can be used for structural bracing of mid-rise buildings and efficiently combined with an (excentric) core for high-rise buildings.}, language = {en} } @misc{FreymannSchauerBleicher, author = {Freymann, Konrad and Schauer, Thomas and Bleicher, Achim}, title = {Lifetime extension for steel railway bridges using additional damping : a case study for an existing bridge}, series = {IABSE Symposium 2025, Environmentally Friendly Technologies and Structures - Focusing on Sustainable Approaches, May 18-21, 2025, Tokyo, Japan}, journal = {IABSE Symposium 2025, Environmentally Friendly Technologies and Structures - Focusing on Sustainable Approaches, May 18-21, 2025, Tokyo, Japan}, publisher = {International Association For Bridge And Structural Engineering (IABSE)}, address = {Z{\"u}rich}, isbn = {978-3-85748-206-9}, doi = {10.2749/tokyo.2025.1885}, pages = {1885 -- 1893}, abstract = {Steel bridges as slender and highly articulated lightweight structures are exceedingly exposed to fatigue damage due to traffic. Especially railway traffic is causing significant stress variations, the material can only withstand a limited amplitude and number of stress cycles. This results in a reduced lifetime of the bridge. This paper gives an overview of the material behaviour of steel due to fatigue. The lifetime capacity of an existing bridge as reference is analysed according to the current state of technology based on a simplified FE-Model. Further, the potential for extending the lifespan by reducing the vibration cycles through additional damping is numerically investigated for the referred bridge. A possible direct correlation between fatigue-relevant stress and the remaining service life of the existing bridge is demonstrated.}, language = {en} } @phdthesis{Marker, author = {Marker, Paul}, title = {Generalized method for an efficient design of active hybrid structures : in the stress field between stiffness and compliance}, publisher = {Brandenburgische Technische Universit{\"a}t}, address = {Cottbus ; Senftenberg}, issn = {2569-2798}, doi = {10.26127/BTUOpen-6946}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-69466}, pages = {xxviii, 275}, abstract = {In structural engineering, active structures that combine the principles of lightweight construction with flexible component behavior are increasingly being realized. Within this approach, the lightweight design offers material-efficient structures which, due to their reduced mass, provide a good basis for an energy-efficient actuation. In addition, the use of flexible component behavior provides the possibility to keep the number of required actuators as low as possible, while maintaining a high degree of adaptability. Therefore, the resulting active hybrid structures represent a promising approach with respect to the development of sustainable active structures in our built environment. Due to a larger number of relevant objectives, this new kind of structures requires a higher design effort compared to classical structures from the field of structural engineering. This dissertation aims to contribute to a more efficient and generalized design process for active hybrid structures. In order to achieve this goal, several strategies have been investigated. First of all, useful target criteria related to the mentioned relevant areas are derived. These should enable a more target-oriented design and provide a basis for formulating appropriate target weighting, allowing the development of ideal compromise solutions that combine structural stiffness, bending elastic transformation behavior and an efficient actuation concept. In addition, a variety of approaches have been investigated to improve the design process of active hybrid structures in a broad stress field between stiffness and compliance. These mainly include the aspects of structure generation, analyses for an optimal load transfer as well as the determination of an associated optimal actuation concept. In the context of this thesis, different subroutines are investigated for the mentioned partial steps of an overall hierarchical method which were implemented in a software application. Some variations of this generalized method were applied to diverse structural case studies of cantilevered systems with different degrees of structural stiffness. Three of these examples, representing segments of roof structures that differ in terms of their bending elastic transformation behavior, were analyzed in more detail in this thesis. These analysis results were verified on real active hybrid prototypes.}, subject = {Tragwerk; Leichtbau; Hybridbauweise; Bauentwurf; Software}, language = {en} }