Summary
Stress ribbon bridges experience excessive vibration when subjected to moving vehicles due to flexibility and low damping, affecting the running safety and ride comfort of the vehicles. It is ...of great challenge to suppress the vibration of a vehicle‐stress ribbon bridge (VSRB) system because of the strong geometric nonlinearity of the stress ribbon bridge, which might also lead to the inapplicability of the conventional optimal design of tuned mass dampers (TMD). This paper proposes an eddy‐current tuned mass damper (ECTMD) and its parameter optimization method for suppressing the excessive vibration of stress ribbon bridges subjected to moving vehicles. A dynamic analysis method of the VSRB system is first presented for evaluating the control performance of the ECTMD. Then, a response surface method is proposed to optimize the parameters of the ECTMD for improving control performance. The control performance of the ECTMD optimized by the proposed procedure is validated using a numerical study of a real stress ribbon bridge. Numerical results demonstrate that the conventional design methodology of the TMD based on the linear theory is not the optimal design for the VSRB system due to its nonlinear vibration feature, whereas the proposed response surface method well optimizes the ECTMD's parameters, thus achieving the optimal control performance. This study provides an effective passive control approach for reducing the dynamic responses of stress ribbon bridges excited by moving vehicles.
This paper describes the development of an active vibration control system for a light and flexible stress ribbon footbridge. The 13 m span carbon fiber reinforced plastic (CFRP) stress ribbon bridge ...was built in the laboratory of the Department of Civil and Structural Engineering, Berlin Institute of Technology. Its lightness and flexibility result in high vibration sensitivity. To reduce pedestrian-induced vibrations, very light pneumatic muscle actuators are placed at handrail level, introducing control forces. First, a reduced discretized analytical model is derived for the stress ribbon bridge. To verify the analytical prediction, experiments without feedback control are conducted. Based on this model, a delayed velocity feedback control strategy is designed. To handle the nonlinearities of the muscle actuator, a subsidiary force control is implemented. Then the control performance from numerical simulation is verified by experiments under free vibration. As a result, analytical analyses agree well with experimental results. It is demonstrated that handrail-introduced forces can efficiently control the first mode response.
Stress-ribbon systems develop the most flexible and slender bridges. A structural system of such elegant bridges consists of cables or ribbons and deck slabs placed to these strips to distribute the ...live load. Although this structural system is simple, the design of such structures is a challenging issue. Design limitations of the bridge deck slope induce considerable forces in the ribbons, which transfer the tension to massive foundations. The deformation increase under concentrated and asymmetrical loads causes another problem of stress-ribbon bridges—the kinematic component, the design object of such structures, exceeds the dead load-induced vertical displacement several times. This paper introduces a new concept of such a structural system, comprising ribbons made of flexural-stiff profiles. The proposed approach to reduce kinematic displacements is illustrated experimentally by testing two pedestrian bridge prototypes with different flexural stiffness of the steel ribbons. Numerical models calibrated using the test results are used for the parametric analysis of the flexural stiffness effect on the deformation behaviour of the bridge system with steel and fibre-reinforced polymer (FRP) ribbons. A practical approach to the choice of the efficient flexural stiffness of the ribbon-profiles is also proposed.
AbstractThe most slender and flexible footbridges are stress ribbon bridges. One kind of these elegant and simple bridges consists of two hanging steel ribbons, usually made of steel, which carry ...concrete deck panels and are anchored between two heavy abutments. At the anchorage and on intermediate supports the ribbons are often supported by saddles that are curved so that the additional bending stresses in the ribbon, which occur there, stay within allowable limits. The magnitude and the distribution of the bending stresses, the transverse pressure the ribbons exert on the saddle, and stress changes in the region of the detachment point caused by live loads are crucial for the dimensioning of these ribbons. A clear understanding of these issues via parametric studies, analytical solutions, and confirmation by finite-element (FE) analyses are provided in this paper. The findings presented here can also be used for other saddle systems, such as those used in cable-stayed and extradosed bridges.
The article discusses the main component parameters and their interdependencies for a composite stress ribbon trough arch structure. The paper presents a methodology for balancing the combined ...suspension through arch steel bridge structure, suggests analytical methods for putting together the bearing components of the bridge and considers rational component parameters.
The paper describes a study to characterize intentional human dynamic loads (vandal loads) and their induced effects on a footbridge. A numerical model to characterize the dynamic behavior of the ...footbridge has been developed, is experimentally validated, and is used to numerically simulate the response induced by groups of pedestrians synchronized at critical bridge frequencies. The vandal load associated with a single pedestrian is characterized and compared with definitions in the literature. The response is then calculated considering the measured load and compared with the measured response to the excitation induced by a single pedestrian or a group with varying dimensions. The definition of a general load model for vandal excitation, including a tentative definition for synchronization is discussed.
Neue Materialien und Technologien erlauben nicht nur Entwurf und Konstruktion ultraleichter und schlanker, sondern auch nachhaltiger Brücken. Mit dem höchstfesten Material kohlenstofffaserverstärkter ...Kunststoff wurde eine Spannbandbrücke entworfen und gebaut, die mit nur 1 mm Konstruktionshöhe 13 m weit spannt. Um ihre außergewöhnlich hohe Schwingungs anfälligkeit unter Fußgängerverkehr zu reduzieren, wurde eine aktive Schwingungskontrolle entwickelt und an einem Prototypen getestet. Das Konzept zur aktiven Schwingungskontrolle basiert auf dem geregelten Eintrag von Kräften in die Geländerkonstruktion. Zum Einsatz kommen Sensoren, Regelungskonzepte und biologisch inspirierte Aktuatoren, die als aktives System die ersten drei vertikalen Eigenschwingungen der Brücke kontrollieren. Ein wesentliches Element im Entwicklungsprozess des aktiven Systems ist die analytische Modellbildung der Spannbandbrücke, welche dem Entwurf modellbasierter Regelungen zur Kontrolle der Brückenschwingungen dient. Die Effektivität der aktiven Schwingungskontrolle zeigt sich dann durch eine deutliche Reduktion fußgängerinduzierter Beschleunigungen um bis zu 90 % und bestätigt damit auch das Potenzial aktiver Systeme.
Multimodal active vibration control of a stress ribbon bridge using pneumatic muscle actuators.
New materials and technologies not only allow building ultralight and slender bridges, they also enable the construction of sustainable bridges. By using high‐strength carbon fibre reinforced plastic, a very light and flexible stress ribbon footbridge with a span of 13 m and a structural height of only 1 mm was designed and built in the lab of the Chair of Conceptual and Structural Design at TU Berlin. In order to counteract the high level of pedestrian‐induced vibrations, an active vibration control concept was developed and applied to the prototype. This concept consists of sensors, closed loop controls and biologically inspired actuators. The actuators are embedded into the handrail to control the first three vertical modes of the bridge. One basic element for the development of the active system is the modelling of the bridge to design model‐based controller. The efficiency of the multimodal active vibration control and the potential of active systems are shown by an enormous reduction of pedestrian‐induced accelerations up to 90 %.
A newly developed numerical model for the analysis of stress-ribbon bridges under the short-term (static and dynamic) and long-term loads and actions is presented in the paper. The model can simulate ...main nonlinear effects of the behaviour of these structures, including nonlinear behaviour of materials, change in the structure geometry, phased construction, prestressing, etc. Basic solutions for the stress-ribbon bridge over the Cetina River near Zadvarje, and some results of its calculation using the developed numerical model, are presented.
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