Search Results (78)

This study investigates physics-informed and data-driven hybrid modeling strategies for an automotive-grade electrohydraulic (EH) semi-active damper system. Although deep sequence learning architectures such as Long Short-Term Memory (LSTM) networks and Transformers can provide high predictive accuracy, purely data-driven approaches may struggle to preserve physical consistency and maintain robustness under unseen operating conditions. These limitations become more pronounced for EH dampers, whose hysteretic characteristics exhibit highly nonlinear and non-proportional variations under different current and frequency excitations, unlike the more scalable behavior commonly observed in magnetorheological (MR) dampers. To address these challenges, two physics-informed integration strategies are investigated. The first strategy combines physical and data-driven models through parallel loss-function synthesis. The second strategy introduces a learnable physics layer (PINN-Hybrid), in which the coefficients of the extended hyperbolic tangent formulation are adaptively learned within the neural network architecture. In this framework, the physical model acts as a structural regularization mechanism that guides the learning process while preserving the flexibility of data-driven sequence modeling. The proposed models are evaluated under abrupt valve-control operating conditions. Comparative results indicate that the proposed physics-informed architectures improve hysteresis continuity, physical plausibility, and robustness compared with purely data-driven approaches, particularly in low-velocity and transition regions. The proposed framework therefore demonstrates the potential of physics-informed learning strategies for reliable real-time modeling of nonlinear automotive EH damper systems. Full article

The nitrile butadiene rubber-based viscoelastic damper (NVED) has been proven effective in improving the seismic performance of various types of structures. This study proposes to enhance the hysteretic behavior of traditional Chinese wooden joints using the NVED. The cyclic tests on the NVED are first conducted to derive their mechanical properties. Secondly, two configurations of the mortise-tenon joints are selected as the prototype models to fabricate four specimens, and the hysteretic loading tests are conducted on the specimens to derive their hysteretic behaviors. Comparisons are made between the models with and without the NVED to clarify its reinforcing effects. On the basis of the test results of the mortise-tenon joints and the NVED, a simplified simulation method is proposed to represent the joints with the NVED. The test results show that the installation of the NVED can remarkably improve the hysteretic performance of mortise-tenon joints throughout the entire loading process. Compared with the unreinforced joints, the bearing capacity and energy dissipation of the NVED-reinforced specimens can increase by approximately 40%, particularly under large deformation conditions. The proposed simplified simulation method, which adopts zero-length elements to simulate the rotational response of the joints and the NVED, can adequately capture the pinching effect as well as the stiffness and strength degradation of the NVED-reinforced mortise-tenon joint models. Full article

Modern Chinese traditional-style buildings (MCTBs) preserve the beam–column –construction of historical architecture, but the irregularity of joints continues to constrain their seismic performance. To enhance the energy-dissipation capacity of these joints, viscous dampers were installed at the Que-Ti braces (cantilever corbels beneath beam ends) of beam–column joints. Six 1/2.6-scale specimens were designed and tested under periodic dynamic loading. The experimental results indicate that the installation of viscous dampers significantly improved the failure modes by delaying the formation of plastic hinges at beam ends, as well as the initiation of base material cracking and weld fracture. After damper installation, the joint strength increased by 18–46%, and the improvement was more pronounced in double beam–column joints. A finite element model was established in ABAQUS to investigate the effects of axial load ratio, damping coefficient and damper length on joint strength, hysteretic energy dissipation, and damper mechanical response. The results revealed that the axial load ratio has a limited influence on the overall joint strength and damper contribution. Increasing the damping coefficient significantly enhances the joint hysteretic energy dissipation and peak damper force, exhibiting an approximately linear relationship. The damper length has a minor influence on joint strength, but a longer damper slightly increases the hysteretic energy dissipation and equivalent viscous damping, while the maximum damper displacement is mainly governed by the damper length. Similar damper contributions are observed in single beam–column and double beam–column joints, indicating stable and reliable energy-dissipation behavior. The proposed numerical approach can predict the axial deformation, velocity, and force demands of dampers under various loading conditions. In addition, preliminary design recommendations for irregular steel joints with supplemental viscous dampers in MCTBs were developed based on ancient Chinese architectural literature and refined through combined experimental observations and finite element analyses (FEA). Full article

With the growing demand for seismic resilience in urban building structures, the development of high-performance energy-dissipation components has become critical for enhancing structural safety and mitigating earthquake-induced damage. Traditional buckling restrained braces (BRBs) are typically designed to remain elastic under frequent earthquakes, limiting their ability to dissipate early seismic energy input. To address this limitation, a novel friction-damped double-stage yield buckling restrained brace (FD-DYBRB) is proposed by integrating friction dampers (FDs) with a conventional BRB. The mechanical performance of both the traditional BRB and the proposed FD-DYBRB was investigated through cyclic loading tests. Additionally, to evaluate the performance differences among various configurations, a cross-shaped double-stage yield BRB was also tested for comparison. The experimental results demonstrate that the proposed FD-DYBRB design is highly effective, exhibiting plump hysteretic curves and distinct double-stage yielding characteristics. Specifically, the FD-DYBRB possesses an initial stiffness ranging from 249.38 kN/mm to 250.31 kN/mm, which is comparable to traditional BRBs. Under small displacements, its equivalent damping ratio increases by approximately 7% for every 50 kN increase in friction force, achieving continuous early-stage energy dissipation. Furthermore, the proposed brace realizes full-process energy dissipation by maintaining stable average tensile and compressive capacities of 87.08 kN and 84.50 kN, respectively, even after the core plate fractures. Compared to the traditional BRB, the maximum dissipated energy of the FD-DYBRB increases by 23.55% to 54.75%, and its maximum equivalent damping ratio exceeds that of the cross-shaped DYBRB by 5%. These findings offer a reliable technical solution for improving the seismic performance of high-rise and long-span buildings, ultimately helping to mitigate structural damage and protect life and property during seismic events. Full article

Magnetorheological (MR) dampers exhibit significant hysteretic nonlinearities, particularly under dynamic operating conditions, where accurately modeling the complex coupling between magnetic flux density and excitation current remains challenging. To overcome the limitations of the conventional static Jiles–Atherton (JA) model in capturing dynamic hysteresis responses, a dynamic JA model incorporating multiple loss mechanisms (LS-DJAM) is proposed for MR dampers. Building on loss separation theory, the model integrates eddy current and excess loss mechanisms to more accurately represent the dynamic hysteresis behavior of MR dampers. By coupling the Bingham mechanical model, a magneto-mechanical constitutive relation for MR dampers is established. Furthermore, to enhance the accuracy of LS-DJAM parameter identification, a hybrid particle swarm optimization–genetic algorithm (PSO–GA) is developed. Genetic operators are embedded within the PSO framework to strengthen the global search capability and mitigate premature convergence, thereby enabling efficient LS-DJAM parameter identification. The proposed LS-DJAM, identified via the PSO–GA, significantly enhances the modeling of MR damper output forces. PSO–GA parameter estimation improves accuracy by over 60%, and the LS-DJAM reduces the maximum modeling error by 87.5% compared with the conventional JA model. It accurately captures the dynamic hysteresis characteristics of MR dampers, providing a robust theoretical basis and practical framework for high-performance control and engineering optimization. Full article

Passive energy dissipation (PED) devices have been widely accepted as effective in reducing seismic effects through extensive experimental and analytical studies. However, the estimation of the supplemental damping ratio (SDR) and its relationship with seismic performance levels remain important research challenges. In this study, a supplemental damping-based procedure is proposed for the design and retrofit of reinforced concrete buildings equipped with PED systems. The proposed procedure essentially consists of two main parts, which define the overall methodological framework. The first part of the procedure is developed to establish a relationship between target seismic performance levels and SDR by explicitly considering the structure–damper interaction, rather than predetermining damping or structural parameters. The second part analytically establishes a direct relationship between the target seismic performance of the structure and the required SDR provided by fluid viscous dampers (FVDs). The results of 5808 nonlinear time history analyses indicate that the supplemental damping ratio plays a critical role in structural performance and provides significant reductions in hysteretic energy demand depending on the device characteristics, configuration, and arrangement. In addition to the key parameters of the damping system mentioned above, the proposed procedure also considers key parameters of the structural system. Furthermore, it allows these parameters to be evaluated separately with respect to seismic performance levels. Consequently, the first part of the procedure provides a detailed basis for damper optimization and realistically reveals the effects of supplemental damping on the seismic performance of new and existing reinforced concrete buildings equipped with PED systems. Furthermore, the second part offers a non-iterative and practical solution for the performance-based design and retrofit with FVDs. Full article

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

Designing long-span cable-stayed bridges in high seismic hazard zones presents significant challenges due to their flexible structural systems, the influence of multi-support excitation, and the need to control large displacements while limiting seismic demands on critical components. These difficulties are further amplified in regions with complex geology and for bridges required to maintain high levels of post-earthquake serviceability. This study develops a low-damage seismic design approach for long-span cable-stayed bridges and demonstrates its application in the New Panama Canal Bridge. Probabilistic seismic hazard assessment and site response analyses are performed to generate spatially varying ground motions at the pylons and side piers. The pylons adopt a reinforced concrete configuration with embedded steel stiffeners for anchorage, forming a composite zone capable of efficiently transferring concentrated stay-cable forces. The lightweight main girder consists of a lattice-type steel framework connected to a high-strength reinforced concrete deck slab, providing both rigidity and structural efficiency. A coordinated girder–pylon restraint system—comprising vertical bearings, fuse-type restrainers, and viscous dampers—ensures controlled stiffness and effective energy dissipation. Nonlinear seismic analyses show that displacements of the girder remain well controlled under the Safety Evaluation Earthquake, and the dampers and bearings exhibit stable hysteretic behaviours. Cable tensions remain within 500–850 MPa, meeting minimal-damage performance criteria. Overall, the results demonstrate that low-damage seismic performance targets are achievable and that the proposed design approach enhances structural control and seismic resilience in long-span cable-stayed bridges. Full article

This study develops a hyperbolic tangent-based model for the hysteretic behavior of automotive grade electrohydraulic semi-active dampers. Model parameters were identified from experimental force–velocity data gathered under sinusoidal excitations across 1–6 Hz and 0.38–1.6 A. The calibrated model was integrated into an IPG CarMaker 13.0/Simulink 2022b co-simulation to assess performance under ISO-compliant road profiles and realistic driving scenarios. Comparative analysis with conventional nonlinear damper models was conducted, focusing on ride comfort metrics such as vertical acceleration, pitch rate, and roll rate. The results demonstrate that the proposed model provides improved fidelity in replicating real damper behavior and enables more realistic assessment of semi-active suspension performance in virtual vehicle development platforms by providing reduced vertical acceleration errors by >5 dB (2–6 Hz) compared to nonlinear models. Full article

Passive metallic dampers are critical for the seismic resilience of structures, yet their design has historically relied on incremental modifications rather than systematic optimization. This study introduces and validates a data-driven workflow that combines the Taguchi method with nonlinear finite element analysis to design novel U-shaped seismic dampers (USSDs) with superior performance. Building on an experimentally validated computational model from prior work, an L25 orthogonal array was employed to systematically investigate key geometric parameters, with an Analysis of Variance (ANOVA) identifying height, thickness, and length as the most influential factors on damper behavior. This statistical insight guided the creation of two optimized models, with the UD-M4 model demonstrating a nearly seven-fold increase in total energy dissipation (340.6 kJ vs. 51.2 kJ), a nine-fold increase in stiffness, and a 50% improvement in deformability compared to the commercial UD-40 baseline. The primary contribution of this work is the validation of an efficient statistical–computational methodology for the performance-based design of next-generation seismic protection devices, moving beyond traditional trial-and-error approaches. Full article

The use of dissipative bracing systems by hysteretic dampers represents one of the most efficient innovative techniques for the seismic retrofitting of existing structures, especially for reinforced concrete (RC) frame buildings. Many studies on design approaches and case studies have been developed in recent decades and are still in progress; however, the importance of the relation between the properties of the existing structure and of the damper system has not been analyzed, and the influence of the type of arrangement inside or outside the structure, has not been pointed out. In this paper, an innovative dimensionless approach is proposed to describe the dynamic structural properties of the retrofitted structure introducing ratios between the properties of the existing structure and damper system. Therefore, indications to optimize the design of the passive energy dissipation (PED) system can be clearly established for each case. Furthermore, a generalization of the design approach considering different solutions with internal and external bracings is proposed. The application of the dimensionless parameters to the design of a dissipation system for a single-bay three-story RC frame building and points out that damping can be reduced by two times if the capacity of the existing structure is used, further reducing the base shear transmitted to foundation. This result is also obtained by mounting the PED system on an external structure. The effect of infill walls on the stiffness of the existing structure requires an increment of the stiffness of the PED system with double the stiffness of the devices further than the buckling-restrained braces (BRBs). Full article

Friction dampers are widely used in building seismic protection due to their excellent shock-absorbing performance and reliable operation. To clarify the influence of friction plate material properties on the hysteretic behavior and stability of friction dampers, this study selected three materials with distinct physical properties (density, hardness, and stiffness)—titanium alloy, brass, and zirconia ceramic—as friction plate candidates. Three sets of low-cycle reciprocating load tests were designed to obtain the hysteretic curves of dampers with different friction plates and analyze their energy dissipation capacity and operational stability. Results show that the hysteretic curves of the copper-steel and titanium-steel plate specimens are close to the ideal rectangular shape, with symmetric force–displacement relationships and stable energy dissipation. The copper-steel plate exhibits strong energy dissipation capacity and high cost-effectiveness, while the titanium-steel plate has moderate energy dissipation capacity but stability comparable to that of the copper-steel plate. In contrast, the friction force of ceramic-steel plate specimens shows obvious divergence as displacement increases, leading to poor overall stability. The friction coefficient between the friction plate material and the main plate material exerts a significant influence on the damper’s energy dissipation, and a stable friction mode serves as a guarantee for its normal operation. Full article

In this paper, the vibration of a wheel running on a light rail equipped with rail dampers that use a mixed damping system (rubber–oil) is investigated under the excitation of random roughness on the rolling surfaces, to demonstrate the influence of such rail dampers on the dynamic behaviour at the wheel–rail interface. For this purpose, a model is adopted in which a rigid wheel moves at constant speed over a rail modelled as an infinite Timoshenko beam, supported by elastic foundations with an internal degree of freedom that represents the behaviour of the rail pads, sleepers, and ballast. The rail dampers are represented as two-mass oscillators, while the internal friction in the elastic components of the wheel–rail system is modelled using hysteretic damping. To obtain the time series of the rail and wheel displacements, as well as the wheel–rail contact force, the convolution theorem is applied in a heuristic manner, making use of the relationship between Green’s functions in the time and frequency domains through direct and inverse Fourier transforms. The results show that (a) rail dampers primarily affect rail dynamics and the wheel–rail contact force over a relatively wide frequency range, while having little influence on wheel motion; (b) rail dampers are highly effective in reducing rail vibration and the wheel–rail contact force when the rail pads are stiff, but considerably less effective when soft rail pads are used; and (c) they may slightly amplify the contact force at the lower edge of their effective frequency range. Full article

Aiming to address the seismic vulnerability of long-span continuous rigid-frame bridges in high-intensity seismic zones, this study proposes to use a novel annular steel wire rope damper spherical bearing (SWD-SB) to dissipate the input earthquake energy and reduce the seismic responses. Firstly, the structural configuration and mechanical model of the new isolation bearing are introduced. Then, based on the dynamic finite element formulation, the equation of motion of a continuous rigid-frame bridge with the new isolation bearings is established, where the soil-structure interaction is considered. In a practical engineering case, the dynamic responses of the Pingchuan Yellow river bridge with the SWD-SB bearings are calculated and analyzed under multi-level earthquakes including the E1 and E2 waves. The results show that, compared with the bidirectional movable pot bearings, the SWD-SB significantly reduces the internal forces and displacement responses at the critical locations of the bridge. Under the E2 earthquake, the peak bending moments at the basement of main piers and at the pile caps are reduced by up to 72.6% and 44.7%, respectively, while the maximum displacement at the top of the main piers decreases by about 34.6%. The overall structural performance remains elastic except the SWD-SB bearings, meeting the two-stage seismic design objective. This paper further analyzes the hysteretic energy dissipation characteristics of the SWD-SB, highlighting its advantages in energy dissipation, deformation coordination, and self-centering capability. The research results demonstrate that the steel wire rope isolation bearings can offer an efficient and durable seismic protection for long-span continuous rigid-frame bridges in high-intensity seismic regions. 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