Search results for "Damper"
showing 10 items of 107 documents
Stochastic seismic analysis of structures with nonlinear viscous dampers
2007
Fluid damper devices inserted in buildings or bridges are commonly used as energy sinks for seismic protection. In the response analysis of structures with filled damper devices the main problem exists in the strong nonlinear behavior of such equipment, as a consequence the differential equation of motion remains nonlinear and the response spectrum analysis still cannot be applied. In this note, by using the concept of power spectral density function coherent with the elastic response spectrum and by using the statistical linearization technique, expressions for finding the equivalent linear damping have been found. Comparisons with results obtained by Monte Carlo simulations confirm that f…
Experimental determination of viscous damper parameters in low velocity ranges
2017
In the last decades many strategies for seismic vulnerability mitigation of structures have been developed through analytical studies and experimental tests. Among these, energy dissipation by external devices assumes a great relevance for the relative design simplicity, even if applied to complex structures, and the effectiveness in reducing seismic demand. In particular, the use of fluid viscous dampers represents a very attractive solution because of their velocity-dependent behaviour and relatively low costs. The application on structures requires specific study under seismic excitation and a particular care of structural details. In this context the use of proper constitutive models fo…
On the moving load problem in beam structures equipped with tuned mass dampers
2017
This paper proposes an original and efficient approach to the moving load problem on Euler–Bernoulli beams, with Kelvin–Voigt viscoelastic translational supports and rotational joints, and in addition, equipped with Kelvin–Voigt viscoelastic tuned mass dampers (TMDs). While supports are taken as representative of external devices such as grounded dampers or in-span supports with flexibility and damping, the rotational joints may model rotational dampers or connections with flexibility and damping arising from imperfections or damage. The theory of generalised functions is used to treat the discontinuities of the response variables, which involves deriving exact complex eigenvalues and eigen…
Experimental characterization of friction properties of materials for innovative beam-to-column dissipative connection for low-damage RC structures
2023
Low-damage design of structures in seismic-prone areas is becoming an efficient strategy to obtain "earthquake-proof" buildings, i.e. buildings that, even in the case of severe seismic actions, experience a low or negligible amount of damage. Besides the safeguard of human lives, this design strategy aims also to limit the downtime of buildings, which represents a significant source of economic loss, and to ensure an immediate occupancy in the aftermath of an earthquake. In this context, focusing on moment-resisting frames (MRFs), several solutions have been developed for the beam-to-column connections (BCCs) of steel and precast/prestressed concrete structures, but very few for cast-in-sit…
Innovative connections for steel-concrete-trussed beams: a patented solution
2023
The most recent design strategies welcome the adoption of innovative techniques for seismic energy input mitigation, aiming to achieve high dissipation capacity, prevent the structure from collapse and ensure the serviceability of the construction. Friction damper devices have been widely adopted in framed steel structures for decades, while their introduction in different structural types is still under investigation. This paper presents the outcomes of innovative research supported by the industry and conducted on beam-to-column connections of RC structures in which the beams are Hybrid Steel-Trussed Concrete Beams (HSTCBs) and the columns are classical RC pillars. An innovative solution,…
Stochastic sensitivity of steel frames with connection dampers by modal analysis
2002
A procedure for evaluation of dynamic response sensitivity of multistory steel frames with added viscoelastic beam to column connections by modal analysis is presented. The connection behavior is modeled by a Kelvin-Voigt element, consisting of a rotational spring and a dashpot connected in parallel. Consistent mass, stiffness and damping matrices of the multistory frame are utilized, leading to a structure modeling as a non-classically damped system. The procedure is based on the dynamic modification method, that allows to evaluate the response of non-classically damped structure by modal superposition, without transformation in the complex space. The differential equations governing the e…
Seismic response of RC frames with HSTC beams endowed with friction damper devices
2019
The aim of this work is to compare the seismic response of RC frames built using Hybrid Steel-Trussed Concrete Beams (HSTCBs) whether or not equipped with friction damper devices installed at the beam-to-column joints. Due to their small depth-to-span ratios, HSTCBs usually lead to a large amount of rebar within the beam-column joint, potentially reducing its cyclic performance. Therefore, the adoption of a friction system at the beam-tocolumn joint provides two main advantages, i.e. limiting the shear forces, and thus the potential damage, in the panel zone thanks to the increasing of the bending moment lever arm, and assigning to the device the task of dissipating the incoming seismic ene…
Design of friction connections in R.C. structures with hybrid steel-trussed concrete beams
2019
In this work a feasibility study on the use of friction devices within beam-to-column joints of RC structures is conducted. The connection is made between RC columns cast in-situ and semi-prefabricated steel-concrete beams, named Hybrid Steel-Trussed-Concrete Beams (HSTCBs). Nowadays, HSTCBs are widely adopted in civil and industrial buildings and, therefore, it is required to evaluate their compliance with the capacity design criteria and their seismic energy dissipation capability. However, the design of the reinforcement of such beams usually lead to the adoption of large amount of steel within the panel zone which becomes potentially vulnerable to the effects of seismic cyclic actions a…
Study of a Semi Active Electromagnetic Regenerative Suspension
2016
The main objective of this work is the theoretical and numerical study of a device that allows recovering energy from an automobile suspension. In place of the viscous damper, which dissipates the kinetic energy of the vehicle due to rough roads or more marked obstacles, an electromagnetic damper performs the functions of the viscous shock absorber with a recovery of electric energy. The damper has permanent magnets and its working is based on the electromagnetic induction. The used ferromagnetic material is the Supermendur, which has very good ferromagnetic properties, but is expensive and difficult to found, so that the choice of different material is useful to reduce the costs. The mathe…
Design of an Electromagnetic Regenerative Damper and Energy Harvesting Assessment
2016
Design of an electromagnetic regenerative shock absorber is proposed in this paper. In order to increase the efficiency of land vehicles the sources of energy losses have to be eliminated, or reduced. For this reason, several systems, recovering kinetic energy and converting it into electrical power, were studied and designed in the last years. This energy, converted into heat in traditional systems, is recovered to increase the autonomy of the vehicle. The proposed device is constituted by a stator part which coils are placed in an innovative disposition. The moving part is constituted by a rod made in stainless steel with alternated permanent magnets and spacers, so that the relative moti…