FG Hybride Konstruktionen - Massivbau
Tall buildings are increasingly built worldwide due to significant economic benefits in dense urban land use. But super-slender tall buildings are very susceptible to wind excitation. Tuned Mass Damper (TMD) and distributed-Multiple Tuned Mass Damper (d-MTMD) have been widely investigated passively and actively and proven to be e cient solutions to mitigate the structure vibration. However, they both need additional mass and huge installation space near the top of the building. In this contribution, a new semi-active distributed-Multiple Tuned Façade Damper (d-MTFD) is investigated that employs the mass of the outer skin of a Double-Skin Façade (DSF) as damping mass. The outer skin of DSF at the upper storeys of the building are parallel moveable to the inner skin fixed on the primary structure. A design criterion besides the damping of the primary structure vibration is that the relative displacement of the outer skin with respect to the inner skin fixed on the primary structure should not be too large. Otherwise, it makes the occupants feel uncomfortable and imposes too high constructional demands. Therefore, on-o ground-hook control is investigated, where the two control objectives are optimized using genetic algorithms. One control objective is to minimize the peak top floor acceleration, and the other control objective is to reduce the maximum peak relative displacement of all the moveable outer skins. This multi-objective optimization results in a Pareto Front, which allows choosing controller settings that yield a good trade-o between both objectives. The approach has been first validated in a simulation with a 306 m benchmark 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 top floor accelerations for hotel usage and a maximal displacement between the primary structure and the moveable outer skin less than ± 0.5 m could be achieved despite the presence of rolling friction. The variable damping coe cients for the on-o ground-hook control can be realized by means of a stepper motor in each moveable DSF element which acts as a generator using customized power electronics for energy harvesting. An open research question is if the harvested energy will be su cient for enabling a self-sustainable operation of the embedded control system and power electronics. Further validations will be carried out in Hardware-in-the-Loop (HiL) simulations in which a currently built prototype of one moveable DSF element will be physically connected to the simulation of the benchmark building.
Active Vibration Control of a Convertible Structure Based on a Polytopic LPV Model Representation
(2020)
This paper deals with modeling and control of lightweight convertible structures for the application in civil and structural engineering. Such structures are prone to vibrations due to their lightweight design. In addition, they exhibit transformation state dependent dynamic behavior. In order to guarantee a reliable operation, the use of active vibration control (AVC) is an effective means. For the example of a simplified convertible structure, modeling is demonstrated using the linear parameter-varying (LPV) framework. Based on local linear time-invariant (LTI) models, derived from a finite element model of the convertible structure, a polytopic LPV model is established. This LPV model is then utilized to design a polytopic LPV output-feedback controller for AVC during the structure’s transformation. The effectiveness of the designed controller is validated in simulation.
Facade-Integrated Semi-Active Vibration Control for Wind-Excited Super-Slender Tall Buildings
(2020)
Nowadays, skyscrapers are getting higher and more slender due to inner-city concentration, which makes the structure more susceptible to dynamic excitations. The design of super-slender skyscrapers is governed primarily by wind excitation. A traditional Tuned Mass Damper (TMD) has been installed in many skyscrapers to mitigate wind-induced vibrations, which has been proven to be very reliable. However, it needs large additional mass and huge installation space near the top of the building, which makes TMD not optimal for superslender skyscrapers. In this paper, a semi-active distributed-Multiple Tuned Facade Damper (d-MTFD) using movable facade elements as damping mass is investigated. The facade elements at the upper stories of the building are parallel movable to the primary structure. Electrical Machines (EM) as variable damper are integrated in their connections to realize semi-active vibration control, which makes the system more effective and robust. For real application, a practical design criterion is that the relative displacement of the facade elements cannot be too large, otherwise it makes the occupants feel uncomfortable. Therefore, multi-objective Genetic Algorithm (GA)-optimized on-off groundhook semi-active control is applied, where two control objectives are optimized. One control objective is to minimize the peak top floor acceleration and the other control objective is to minimize the maximum peak relative displacement of all the facade elements. As a result, a Pareto Front shows that better vibration suppression performance and smaller facade relative displacement can be achieved using the multi-objective optimized controller.
Linear Parameter-Varying Models for Convertible Structures in Civil and Structural Engineering
(2019)
This paper investigates the feasibility of the linear parameter-varying (LPV) framework for modelling the dynamic behaviour of ultra-lightweight convertible structures based on the elastic kinetic motion mechanism with a focus on civil and structural engineering applications. Model building is carried out for the example of a Fin Ray structure. In a first step local linear time-invariant (LTI) models are derived from a finite element model of the structure for different transformation states. On the basis of this collection of local LTI models, a grid-based LPV model is established. The derived LPV model is validated in simulation by comparison with data from a finite element model.
Active Vibration Control of a Convertible Structure based on a Linear Parameter-Varying Model
(2019)
This paper investigates modelling and active vibration control (AVC) of ultra-lightweight convertible structures based on the elastic kinetic motion mechanism with a focus on civil and structural engineering applications. Model building is carried out in the linear parameter-varying (LPV) framework for the example of a convertible Fin Ray structure. In a first step local linear time-invariant (LTI) models are derived from a finite element model of the structure for different transformation states. On the basis of this collection of local LTI models, a grid-based LPV model is established. An AVC of multiple modes is implemented by means of a modal velocity feedback control. Single-input single-output (SISO) control design is carried out with the root locus method for the first and second mode using the same control input under the assumption of well separated eigenfrequencies. The implemented AVC is validated in simulation.