## 1 Introduction  
Structures can experience vibrations from different sources, including everyday use, such as pedestrians walking on bridges or vehicles crossing them, fluid/structure interaction effects, which can be derived from wind flow, or infrequent events, such as earthquakes or explosions. Depending on the source and nature of the vibrations, different mitigation strategies are applied, using damping devices and tailored approaches [1]. One strategy to mitigate vibrations is the use of Dynamic Vibration Absorbers, which rely on the out-of-phase movement of a mass with respect to the structure they are attached to. The secondary mass adds one degree of freedom to the system, thus modifying its natural frequencies. This kind of device was originally proposed by [PERSON] at the beginning of the 20 th century [2]. The well-known Tuned Mass Dampers and Tuned Liquid Dampers are further developments belonging to this category. Traditional dampers are limited by their fixed damping characteristics, which can be suboptimal for structures subjected to varying excitation frequencies and amplitudes. On the contrary, Tuned Liquid Dampers (TLDs) are emerging as versatile devices designed to mitigate structural vibrations. These systems are cost-effective, require minimal maintenance, can be designed for temporary or permanent installations, and offer multidirectional and multifrequency applications, making them a promising solution to modern vibration control challenges [3]. These dissipative devices are based on the out-of-phase movement of a fluid, typically water, inside a container relative to the main structure to which they are attached. Over the last 50 years, different modifications on their shape, arrangement, or fluid used for improved functioning have been discussed [3]. Traditional TLDs are limited by their fixed damping characteristics, which can be suboptimal for structures subjected to varying excitation frequencies and amplitudes. Their inherently low damping ratio (approximately 0.5%) further underscores the need for supplementary mechanisms to enhance energy dissipation and improve performance [4]. Incorporating smart materials into TLDs offers a way to passively or semiactively enhance their performance. While these passive control systems are widely used because of their reliability (they activate automatically and need no power supply) [5], semiactive TLDs are attractive control systems because they can adjust their mechanical properties (i.e., when smart fluids are applied) based on real-time measurements of the structural response [6]. The development and optimization of TLDs rely heavily on experimental research. Testing hypotheses through controlled experimentation allows researchers to evaluate how design variables influence performance and identify ways to enhance efficiency. Additionally, experimental validation bridges the gap between theoretical models and real-world applications, ensuring accurate predictions of device behavior under dynamic loads, such as wind or seismic activity [7]. This dual approach of design exploration and validation is critical for advancing TLD technology and ensuring its reliability in practical applications. This study explores the potential of TLDs with magnetic fields for passive and semi-active enhanced vibration control. The research aims to provide a practical background for the development of magnetic TLDs for future breakthroughs in this technology. Magnetorheological fluids (MRFs) are a kind of field-responsive fluid formed by suspensions of magnetic particles in a liquid that exhibit rapid and reversible increases in viscosity upon the application of a magnetic field [8]. When exposed to a magnetic field, the particles align to form chain-like structures along the field lines, significantly increasing the fluid's apparent viscosity and altering its mechanical properties. This unique behavior makes MR fluids highly versatile for applications requiring precise control of damping and stiffness.