Search Results (34)

Metallic seismic dampers are an effective tool for reducing structural damage during seismic events. While previous reviews have often focused on cataloging device types, this review presents a deep analysis of the underlying science governing their performance. Particular emphasis is placed on advanced computational methods, such as non-linear kinematic hardening (e.g., Chaboche) and micromechanical damage models (e.g., GTN), which are essential for accurately predicting low-cycle fatigue and fracture. Furthermore, advances in materials science are analyzed, ranging from low-yield-strength (LYS) steels to self-centering shape memory alloys (SMAs). Finally, the influence of manufacturing processes (including additive manufacturing) is explored, and critical future challenges in design, modeling, and long-term durability are identified. This analysis provides a foundational resource for researchers seeking to advance beyond simple phenomenological design toward physics-based prediction of damper performance. Full article

Chatter is a self-excited vibration that limits productivity, accelerates roll wear and compromises strip surface quality in high-speed tandem cold-rolling. This work presents a predictive hybrid model that couples the strip-deformation physics to the structural dynamics of a five-stand, 4-high mill, providing a fast decision tool for process optimization and real-time control. The model represents each stand as a four-degree-of-freedom mass–spring–damper system whose parameters are extracted from manufacturing automation datasheets and roll-gap sensing. Linearization about the nominal point yields analytical sensitivity matrices that close the electromechanical loop; the delay between stands is also included in the model. Implemented in MATLAB/Simulink, the computational model, based on data provided by Danieli & C. Officine Meccaniche S.p.A., reproduces the onset of chatter for two types of steel. The framework therefore supports automation-ready scheduling, active vibration mitigation and design-space exploration for next-generation mechatronic cold-rolling systems. Full article

To mitigate and control the seismic damage risk of high-speed railway bridges and enhance their post-earthquake reparability, a prefabricated multi-layer parallel-connected slit steel plate shear damper is proposed by utilizing the energy absorption capacity of flexure–shear coupled deformation in dampers. A theoretical model for calculating the stiffness and load-bearing capacity of the proposed damper was established and validated through detailed finite element simulations. The results demonstrate that the damper exhibits stable energy dissipation efficiency under cyclic loading, along with a gradual reduction in post-yield stiffness. Subsequently, a numerical model of the high-speed railway track–bridge-damper systems (HSRTBDS) was developed, incorporating the contribution of the proposed damper to quantify its control over the seismic response of the HSRTBDS. The findings indicate that the damper effectively reduces the seismic responses of the girders, rail fasteners, and track slabs, with a maximum deformation reduction exceeding 30% in the supporting structures. However, the deformation and damage of the bridge piers slightly increased, though they remained within acceptable safety limits. The damper showed limited influence on the damage to rails, fasteners, and shear key slots. Overall, the effectiveness of the proposed damper in controlling the structural response of HSRTBD has been demonstrated and validated, providing insights for the seismic design of high-speed railway bridges in high-intensity seismic zones. Full article

This study develops a novel transverse steel damper (TSD) to enhance the seismic performance of tall-pier girder bridges, featuring superior lateral strength and energy dissipation capacity. The TSD’s design and arrangement are presented, with its hysteretic behavior simulated in ABAQUS. Key parameters (yield strength: 3000 kN; initial gap: 100 mm; post-yield stiffness ratio: 15%) are optimized through seismic analysis under near-fault ground motions, incorporating pulse characteristic investigations. The optimized TSD effectively reduces bearing displacements and results in smaller pier top displacements and internal forces compared to the bridge with fixed bearings. Due to the higher-order mode effects, there is no direct correlation between top displacements and bottom internal forces. As pier height decreases, the S-shaped shear force and bending moment envelopes gradually become linear, reflecting the reduced influence of these modes. Medium- to long-period pulse-like motions amplify seismic responses due to resonance (pulse period ≈ fundamental period) or susceptibility to large low-frequency spectral values. Higher-order mode effects on bending moments and shear forces intensify under prominent high-frequency components. However, the main velocity pulse typically masks the influence of high-order modes by the overwhelming seismic responses due to large spectral values at medium to long periods. Full article

This paper investigated the hysteresis performance of multi-story Y-shaped eccentrically bare braced steel frames with block slit dampers (BSDs). After validating existing models through finite element (FE) analysis, an FE model of Y-shaped eccentrically bare braced steel frames (YEBFs) with BSD (BSD-YEBFs) was established. The influences of different types of BSDs on the hysteresis performance of YEBFs were subsequently analysed, as were the seismic performances of YEBFs with BSD (BSDF) and traditional Y-shaped eccentrically bare braced steel frames (TEBF) under cyclic loading, including the stress failure mode, hysteresis curve, stiffness, strength, and energy dissipation capacity. The results showed that: (1) compared with those of BASE-Y, the ductility coefficients of YEBFs with one level BSD (BSD-1) and two level BSD (BSD-2) increased by 59.57% and 39.47%, respectively, and the lateral bearing capacity decreased by 3.26% and 2.78%, respectively. (2) Compared with those of TEBF, the yield bearing capacity and ultimate bearing capacity of BSDF increased by 3.13% and 11.12%, respectively, and the ductility coefficient increased by 56.7%. Moreover, BSDF possesses higher initial stiffness and more sustained energy dissipation capabilities. Full article

With the aim of achieving a graded-protection braced frame structure and minimizing the excessive residual deformation of traditional metal dampers under intense seismic action, a graded-yield-type metal self-centering brace (SC-GYMB) is proposed. The brace is composed of X-shaped and U-shaped steel plates with different yield point displacements, which jointly dissipate energy. Additionally, it employs a composite disc spring as a self-centering element to provide restoring force for the brace. The brace’s basic structure and working mechanism are described, and the theoretical model for its restoring force is derived. The ABAQUS finite element software (ABAQUS 2021) is utilized to investigate the hysteretic performance of the SC-GYMB under low-cycle reciprocating load, while thoroughly discussing the influence of various model parameters on its key mechanical behavior. The results demonstrate a strong agreement between the theoretical restoring force model and the numerical simulation results. The hysteretic curves of the braces exhibit a distinct “flag” characteristic, indicating excellent energy dissipation capacity and self-centering performance. Moreover, these curves display a hierarchical yield behavior that satisfies the seismic performance requirements for different intensity earthquakes. The deformation mechanism of X-shaped steel sheets transitions from bending deformation during the initial loading stage to tensile deformation in the subsequent loading stage. Increasing the initial pre-compression force of the combined disc spring enhances the restoration performance of the brace. Augmenting the thickness of X-shaped or U-shaped steel sheets modifies the displacement and load at both the first and second yield points, thereby enhancing energy dissipation capacity and bearing capacity of the brace; however, it also leads to increased residual deformation. Full article

Previous research on composite dampers has rarely addressed the issue of large deformations of structures under limit state. However, the proposed damper in this paper takes this issue into account and could provide yielding reserve stiffness for structures, ensuring structural resilience. A composite damper with yielding reserve stiffness (YRSD), consisting of a friction unit and a metal yield unit, was proposed. Low cyclic loading tests with different energy-dissipating steel plate thicknesses and bolt preloads were carried out and experimental results were compared with that of numerical simulation. This paper focuses on the synergistic energy dissipation mechanism of the proposed damper and the effects of various factors on its hysteretic performance, including the bolt preload and thickness of X-shaped steel plates. The results show that the synergistic energy dissipation mechanism of the proposed damper is well, exhibiting the behavior of hardening post-yielding stiffness and multi-stage energy dissipation characteristics, which could provide yielding reserve stiffness for the structure. The experimental hysteresis curve of YRSD is full, indicating its strong energy dissipation capacity, and the skeleton curve of experiment is consistent with that of the theoretical model. The envelope area of the rectangular hysteresis curve of YRSD increases by 107.3% with the preload increased by 100%. When the thickness of the X-shaped steel plates is increased by 2 mm, the resistance of YRSD increases by 26.2% and the post-yield stiffness increases by 37.9%. The stiffness degradation trend of all specimens initially decreases and then increases. The energy dissipation capacity of the friction unit increases by 53.8% as the preload is doubled. The capacity of the metal yield unit increases by 31.7% as the thickness of the X-shaped steel plates is increased by 2 mm. When the energy dissipation capacities of the friction unit and the metal yield unit are close to equal, the optimal energy dissipation capacity of the proposed damper is achieved. The error of results between the numerical analysis and experimentation is less than 10%, providing a basis for the parametric analysis of similar composite damper with yielding reserve stiffness. Full article

To enhance the performance of infill walls and reduce seismic damage, this paper proposes a novel prefabricated reinforced concrete (PRC) energy-dissipating wall, forming a new recoverable energy-dissipating PRC (ED-PRC) structural system. The system features pre-set gaps on both sides and the top of the PRC wall, with flexible materials filling the gaps on the sides. The top of the PRC wall is connected to the beam through several double-conical mild steel dampers to ensure the efficient transfer of horizontal shear forces between the main frame and the PRC wall. A numerical study was employed to investigate the seismic performance and the staged yield capacity. The results show that this design achieves a yielding sequence of dampers → wall → main frame. Furthermore, during the early to mid-phases of the cyclic loading simulations, the double-conical mild steel dampers with the low yield point utilized in the ED-PRC structural system exhibited exceptional energy dissipation capabilities. Notably, the LY100 dampers accounted for up to 61.84% of the total energy dissipation, with the LY160 and LY225 dampers contributing 55.35% and 50.25%, respectively. It indicates that the proposed ED-PRC structural system significantly enhances the ductility and the energy dissipation capacity under seismic loading while substantially reducing damage to the primary structure. The use of prefabricated components facilitates modular construction, allowing for quick dismantling and replacement after an earthquake, thereby rapidly restoring the structural seismic resilience. Full article

Parametric Finite Element (FE) simulations were performed to investigate the ultimate flexural of different configurations of friction steel beam-to-column joints equipped with FREEDAM (free from damage) dampers. The main aim of this study was to compare the effectiveness of friction dampers featuring either single or multiple slotted holes, examining how these variations influence the behavior of the joint and the devices under seismic loads. In particular, the ultimate behavior of the connection (i.e., when the device reaches its maximum stroke) was investigated to characterize the involvement of the bolts in shear, the bearing of the plates, and the yielding of the supporting components. The analysis of bolt stress states revealed significant differences influenced by the number of bolts and slots. The FE models were calibrated against the experimental results obtained within the FREEDAM RFCS Project. These insights contribute to the design and performance evaluation of steel beam-to-column joints with FREEDAM connections, in particular the detailing of the haunch slots, laying the groundwork for future research and applications. Full article

A mild steel-friction self-centering damper with a hybrid energy-dissipation mechanism (MS-SCFD) was proposed, which consisted of a mild steel, frictional, dual-energy-dissipation system and a disc spring resetting system. The structure and principle of the MS-SCFD were explained in detail while the restoring force model was established. The hysteretic behavior of the MS-SCFD under low-cycle reciprocating loading was modeled. Then, the influence of parameters such as the disc spring preload, the friction coefficient, and the soft-steel thickness on the mechanical properties of the MS-SCFD was investigated. The results indicate that the simulation results are basically consistent with the theoretical prediction results, with a maximum error of only 9.46% for the key points of bearing capacity. Since the MS-SCFD is provided with a hysteretic curve in the typical flag type, it will obtain the capacity of excellent self-centering performance. It can effectively enhance the stiffness, bearing capacity, and self-centering capability of the damper after the pre-pressure of the disc spring is increased. The energy-dissipation capacity of the MS-SCFD increases with the increase in the friction coefficient. However, it also increases the residual deformation of the MS-SCFD. The energy dissipation of the MS-SCFD is particularly sensitive to the thickness of mild steel. After being loaded, all components of the MS-SCFD are not damaged except for the plastic deformation caused by the yielding of the mild steel. The normal function of the MS-SCFD can be restored simply by replacing the mild steel plates after the earthquake. Therefore, it can significantly enhance the economy and applicability of the damper. Full article

In regions prone to seismic activity, buildings constructed on soft soil pose a significant concern due to their inferior seismic performance. This situation often results in considerable structural damage, substantial economic loss, and increased risk to human life. To address this problem, this study focuses on the seismic retrofitting of steel moment-resisting frames using friction and metal-yielding dampers, taking into account the soil-structure interaction. The effectiveness of these retrofit methods was examined through a comprehensive non-linear time history analysis of three prototype structures subjected to a series of intense seismic events. The soil behavior was simulated using a non-linear Bouc-Wen hysteresis model. Various parameters, including lateral displacement, maximum drift ratio, the pattern of plastic hinge formation, base shear distribution, and dissipated hysteretic energy, were used to compare the performance of the two retrofit strategies. The findings from the non-linear analyses revealed that both retrofit methods markedly enhanced the safety and serviceability of the deficient buildings. The retrofitted structures exhibited notable reductions in residual displacements and inter-story drift compared to the original frame structures. In the original frame, primary structural elements absorbed a significant amount of the seismic input energy through deformation. However, in the retrofitted frames, dampers dissipated up to 90% of the total input energy. Additionally, integrating dampers into the original frames effectively transferred the non-linear response of the structural elements to the dampers. Full article

The computational modeling of hysteretic dampers is a powerful tool for design, allowing us to predict and optimize damper performance. In this research, a numerical model, based on Chaboche’s nonlinear kinematic hardening constitutive law, was implemented. The parameters of this law were identified and validated by inverse analysis, based on the macro-hysteretic response of the hexagonal honeycomb steel damper. The validated model was applied to simulate the cyclic loading behavior of five proposed steel plate shear yielding dampers (SPSYDs), which were then used to compare the hysteretic performance in terms of effective stiffness, effective damping, and energy dissipation capacity. The parametric analysis of design variables performed on the SPSYDs demonstrated that the plate depth does not modify the effective damping, and the thickness is the most significant factor affecting the maximum displacement, dissipation energy and endurance cycles. The comparison of the performance of the dampers allowed us to establish design guidelines for the SPSYDs, which allow the device to be adjusted with the requirements of the building in which it is installed. Full article

The paper presents the experimental characterization, the formulation of a numerical model, and the evaluation, by means of non-linear analyses, of a new friction damper conceived for the seismic upgrade of existing building frames. The damper dissipates seismic energy through the friction force triggered between a steel shaft and a lead core prestressed within a rigid steel chamber. The friction force is adjusted by controlling the prestress of the core, allowing the achievement of high forces with small dimensions, and reducing the architectural invasiveness of the device. The damper has no mechanical parts subjected to cyclic strain above their yield limit, thereby avoiding any risk of low-cycle fatigue. The constitutive behavior of the damper was assessed experimentally, demonstrating a rectangular hysteresis loop with an equivalent damping ratio of more than 55%, a stable behavior over repeated cycles, and a low dependency of the axial force on the rate of displacement. A numerical model of the damper was formulated in the OpenSees software by means of a rheological model comprising an in-parallel system of a non-linear spring element and a Maxwell element, and the model was calibrated on the experimental data. To assess the viability of the damper for the seismic rehabilitation of buildings, a numerical investigation was conducted by performing non-linear dynamic analyses on two case-study structures. The results highlight the benefits of the PS-LED in dissipating the largest part of seismic energy, limiting the lateral deformation of the frames, and controlling the increase in structural accelerations and internal forces at the same time. Full article

Concentrically braced frame (CBF) systems are susceptible to buckling (which causes a decrease in energy absorption), although this system has considerable lateral stiffness and strength. To over this shortcoming, researchers have suggested the use of I-shaped steel dampers as a practical idea that prevents buckling and increases the energy absorption but reduces the stiffness of the system. To increase the stiffness of the damper, the thickness of the web or the thickness of the flange can be increased, but by increasing their thickness the shear capacity of the damper also increases. Nevertheless, with the increase in the capacity of the damper, the forces created in the elements outside the damper will also increase, which is usually not a suitable solution. Therefore, in this paper, the use of the low yield point for the web plate of an I-shaped damper is proposed to compensate for it. Accordingly, its behavior is investigated parametrically and numerically and also requires equations to design the system proposed. Results indicated that utilizing an LYP damper improves the behavior of the system in the case of energy absorption, stiffness, and strength. Comparing the LYP damper and the conventional I-shaped damper (made of A36 steel) reveals that both dampers pertain to stable hysteresis loops without any degradation, which confirms the capability of the I-shaped damper to dissipate seismic energy. Although the flange plate properties contribute to the load-bearing of the damper, the A36 damper is more affected by the flange plate than the LYP damper that is concluded for LYP dampers the flange plate contribution in the shear strength of the damper is ignorable at the beginning of imposed loading. Full article

In the present work attention is focused on the friction-yielding damper CAR1 (first prototype of Control-Absorb-Retain damper), which belongs to passive energy dissipation systems. This damper consists of very simple materials; it does not need to be accomplished in heavy industry so enables its use in both developing and undeveloped countries. This paper presents and compares two alternative solutions with the use of the CAR1 to seismic retrofit an existing two-story reinforced-concrete (RC) structure with a moment-resisting frame located in Greece and constructed in 1979 and no longer meets the requirements of current anti-seismic regulations. A nonlinear static pushover analysis is performed to assess the performance of the framed building under different levels of shaking (“Life Safety” and “Collapse”). The pushover analysis is carried out in both the x and y directions. The use of damper CAR1 in seismic retrofitting not only provides a base shear load of up to 149.2% and 135.6% for the first and second redesign solutions but also protects steel diagonal braces from buckling. The appropriate characteristics of the dampers CAR1 has been selected from a wide variety of choices and the strengthening level can be easily adjusted or modified during the years based to the appropriate selection or modification of the number, the dimensions, and the elastoplastic properties of the blades. Full article