Clutching inerter damper (CID) has been extensively studied in structural vibration control recently. Because the passive CID device does not take into account flywheel speed reset and cannot achieve an ideal piecewise model, its control performance is limited. Therefore, this study explores the semi-active implementation of the ideal CID model. This paper begins with a comparative study of the ideal and passive analytical models of CID, providing insight into the performance differences and limitations of the two models. Subsequently, an electromechanical clutching inerter damper (ECID) scheme is proposed, which includes energy harvesting and variable inertance. The implementation of the electrical inertance, flywheel speed reset, and energy recovery functions are also discussed, and an electromechanical hybrid simulation model of the ECID is established. This paper thoroughly examines the control and energy recovery performance of the ECID through theoretical and simulation analyses. It explores the effects of resistance and capacitance in the ECID circuit on system performance and demonstrates that the ECID has significant vibration control and energy recovery capabilities. This study presents a comprehensive scheme for the implementation of CID, variable inertance, and energy recovery, which has theoretical reference significance for the development of self-powered semi-active variable inertance devices.

In order to limit the excessive relative displacement between pier and beam, a latticed long-stroke restrainer(LLSR) based on shape memory alloy (SMA) bar is proposed on the basis of single long-stroke shape memory alloy restrainer (LSR). The device consists of SMA alloy bar with excellent superelasticity and re-centering performance, MC nylon, steel pipes and strips or plates. SMA bars can consume ground motion energy and provide re-centering capability. The MC nylon and steel pipe form an anti-buckling system to prevent the SMA bar from buckling under pressure. Firstly, the structure and working mechanism of single long-stroke shape memory alloy damper and lattice long-stroke shape memory alloy damper are described. Secondly, the tensile test of SMA bars under different heat treatment temperature was carried out to determine the SMA bar with the best superelasticity, which was then used as the inner core of the LSR. Then, the axial tension and compression experiment of a single LSR was conducted to further study its mechanical properties. Finally, based on the experimental data of the LSR and the finite element software of ABAQUS, the numerical analysis and parameter analysis of the LLSR were carried out, and the corresponding design method was proposed according to the results of numerical analysis and parameter analysis. The research shows that LLSR not only has stable energy dissipation capacity but also has good re-centering ability.

Reducing the seismic acceleration response of nuclear containment and ensuring the safety of nuclear power equipment under strong earthquakes is of practical significance for improving the seismic toughness of nuclear containment. Tuned mass damper (TMD) can effectively reduce the wind vibration response, but it has the disadvantages of narrow frequency band and low damping efficiency for seismic response control. By combining TMD with inertial volume, a tuned mass damper inerter (TMDI) is proposed to reduce the seismic acceleration of nuclear containment. Based on the performance requirement design idea and H_∞ optimization criterion, an optimal parameter design method for TMDI was established. On this basis, a numerical simulation method is developed by using the substructure idea combined with ABAQUS and Matlab, and the finite element simulation of the seismic response of nuclear containment under TMDI control is realized. The validity of the theoretical analysis is verified by the TMDI seismic control example of a finite element model of a nuclear containment. The results show that the peak acceleration absorption rate of the top of the nuclear containment is 46.1% when TMDI is used, and the tuning mass required when TMDI reaches the same damping index is reduced by 28.2%.

Proton and heavy ion therapy facilities have garnered significant attention and widespread application in recent years due to their high-precision treatment capabilities. Hospitals are often located in urban areas with busy traffic, raising concerns about the potential impact of the road traffic environment on the normal operation of these planned high-precision devices. It necessitates a detailed feasibility assessment of the construction proposal for the project. This paper focuses on an actual engineering project, employing on-site real measurements to study the frequency characteristics of site vibrations induced by road traffic loads and the decay pattern of peak accelerations. A three-dimensional finite element model of the actual structure was developed to analyze the dynamic response of the proton and heavy ion therapy platform influenced by traffic conditions. The findings indicate that the vibrations generated by road traffic are primarily concentrated in the 5 Hz to 20 Hz range. High-frequency vibrations decay rapidly with distance. Peak accelerations of traffic loads at various distances from the road's centerline exhibit a multi-level amplification phenomenon, and in some areas, the peak acceleration may exceed that of the vibration source itself. Through 1/3 octave band analysis, the environmental vibration frequencies mainly affecting the central area of the proton and heavy ion facility range between 5 Hz to 20 Hz and 40 Hz to 60 Hz. Z-vibration level analysis shows that the platform's environmental vibration dynamic response meets the predefined standards for dynamic response design. This study provides a reference for the feasibility demonstration of construction plans considering the impact of traffic environments on facilities requiring high-precision equipment platform stability.

The demountable reinforced concrete column-steel beam (RCS) combined frame consists of reinforced concrete columns, steel beams and demountable connectors. The beam-column joints are connected by bolted shear-resistant connectors, which can realize the disassembly of components for recycling and ensure the effective transfer of forces. However, the seismic performance of demountable RCS frame structure is still unclear, and there is an urgent need to conduct out research on the seismic performance of demountable RCS frame structure. To this end, for the proposed static test of non-demountable conventional RCS frame structure carried out by the team in the early stage, this paper adopts the finite element software ABAQUS to establish a finite element model, and compares the finite element calculation results with the test results through the damage modes, hysteresis curves, skeleton curves, and the cumulative energy dissipation, etc., to effectively verify the accuracy of the numerical simulation. With the help of the same finite element analysis method, a finite element model of the RCS frame with the new demountable connection was established, and the seismic performance of the RCS frame specimens under different node connections was studied in depth, including the force transfer paths, stress maps, hysteresis curves, skeleton curves, stiffness degradation, ductility, and energy dissipation, etc., and the feasibility of realizing the demountability of the frame structure is also analyzed. The results show that: the new demountable joints connection can control the plastic hinge in the region of the distal beam section, effectively protect the joints core area, and improve the ultimate load carrying capacity and stiffness. The hysteresis curve is fuller, slowing down the degradation rate of the load carrying capacity and stiffness, and greatly improving the frame's energy consumption capacity. The specimens with the new demountable joints connection can effectively ensure the continuity of the force transmission path, and its seismic performance indexes are significantly better than the traditional RCS frame structure. The research results and conclusions of this paper can provide a powerful design reference and data support for the seismic design of demountable RCS frame structures.

The failure of porcelain cylindrical electrical equipment during earthquakes is a key factor contributing to power supply outages. The meticulous assessment of the seismic resistance of these devices is a foundational requirement for accurately gauging the overall seismic robustness of power systems. The judicious choice of the support dynamic magnification coefficient plays a crucial role in precisely appraising the seismic behavior of porcelain cylindrical electrical equipment. In this research, to derive the support dynamic magnification coefficients for these devices, vibration tests were carried out on three main types of porcelain cylindrical electrical installations: in cluding disconnect switches, voltage transformers, and current transformers, all of which were evaluated as integrated units with their respective support structures under various seismic excitations and different peak ground acceleration levels. Based on these empirical results, finite element analysis was used to examine the effect of parameters such as the stiffness of supports on the natural frequencies of the equipment-to-support system configurations. This analysis also included a discussion on how the support dynamic magnification coefficients vary with different periodic characteristics of the equipment-support assembly systems. The study findings indicate that, within the scope of this study, the support dynamic magnification coefficient tends to increase as the combined or overall period of the equipment-support system increases. Notably, when the total system period exceeds T_g, the seismic response of the system remains at a relatively high level, significantly exceeding the reference values set by design spectra and clearly surpassing the conservative 1.2 limit established by present guidelines, thus implying a potential underestimate of safety margins. Therefore, it is proposed that the support dynamic magnification coefficient for porcelain cylindrical electrical equipment should optimally not be less than 2.0, and concurrently, the frequency of the supports should not be belower than 30 Hz to ensure enhanced seismic safety measures.

To identify an efficient and accurate feature selection algorithm for filtering seismic intensity indicators, the performance of four common feature selection algorithms, MIC, ReliefF, XGBoost and Lasso, was compared and analyzed. Based on the incremental dynamic analysis results of single-degree-of-freedom structures and the ground motion features, the feature selection regression model was established, the ground motion features was sorted and screened according to the Euclidean distance, the performance of the feature selection algorithm was evaluated according to the screening results, and the least squares regression model was established based on the incremental dynamic analysis results of the 2-storey, 4-storey, 8-storey and 12-storey reinforced concrete frame structures, and the standard deviation change of residual was used to measure the prediction ability of ground motion intensity measure selected by different feature selection algorithms for structural collapse. The results show that the accuracy of the ground motion features screened by the Lasso regression algorithm is 31% higher than that of other algorithms when used for structural collapse prediction. The results can be used as a feature selection algorithm reference for the selection of ground motion intensity measures in the uncertainty analysis of ground motion in the structural vulnerability analysis under the performance-based earthquake engineering (PBEE) framework, and can also be used as an effective feature selection algorithm reference for the selection of ground motion intensity measure s suitable for structural collapse prediction.

Due to process limitation, the laying accuracy of the traditional subway track bed is low, and the construction speed is slow, while the construction accuracy and efficiency of the prefabricated track bed are relatively high. In addition, many subway lines often require the addition of vibration reduction measures or an upgrade in the vibration reduction levels after a period of operation. Therefore, it is urgent to develop the prefabricated damping pad floating slab track (PDPFST) with various vibration reduction grades and convenient upgrade options for vibration reduction. Therefore, the PDPFST was developed and applied to three new metro lines in Qingdao. In this paper, the coupled simulation analysis and field tests were conducted on the dynamic performance and vibration reduction performance of the vehicle passing through the PDPFST. Firstly, the structure and construction technology of the PDPFST were introduced. Then, the requirements and evaluation methods for the simulation and test of dynamic performance analysis and vibration reduction effect analysis were presented. Then, a vehicle-floating slab track-tunnel coupled dynamic analysis model was established. Finally, the coupled simulation results were compared with the field test results. Through the above research, the following conclusions are drawn: Compared to the traditional track slabs, the construction progress of the PDPFST is increased by 3 times (approximately 110 meters per day). The simulation results of the dynamic performance and vibration reduction performance of the vehicle passing through the PDPFST are in good agreement with the measured values, and the dynamic performance of the vehicle meets the requirements. When the vibration frequency is greater than times the natural frequency, the floating slab track can exhibit a good vibration reduction effect. The vibration reduction effect of the PDPFST is remarkable. The high vibration reduction effect is approximately 13 dB and the medium vibration reduction effect is approximately 8 dB. The research results can provide a certain theoretical and practical reference for the design and implementation of the PDPFST.

To study the comfort level of human-induced vibration of a variable section steel-truss pedestrian bridge and the vibration reduction effect of tuned mass damper (TMD), a steel truss girder pedestrian bridge on the Beijing Hangzhou Grand Canal was taken as the research object. Finite element simulation and on-site measurement were used to study the human-induced vibration response of the steel truss pedestrian bridge. Based on the finite element model, the vibration response of the bridge before installation of TMD was analyzed, the pedestrian comfort level was determined, and the influence of pedestrian density, damping ratio and crowd excitation frequency on the bridge was discussed. In this way, the TMD design parameters were given, and the influence of TMD mass ratio on the vibration reduction effect was analyzed. On site measurements were conducted on the pedestrian bridge after the installation of TMD, and based on which acceleration time history and frequency spectrum analysis were used to study the human-induced vibration response of the bridge under corresponding operating conditions. Comparison of the results shows that before installing the TMD, the acceleration response of the bridge exceeds the specification limit, and the effect of human-induced vibration should be considered. In a certain range, the acceleration response increases with the increase of pedestrian density and decreases with the increase of damping ratio. The vibration response increases significantly when the pedestrian step frequency is close to a certain order of the vibration frequency of the bridge. After the installation of TMD, the measured human-induced vibration response of the bridge is reduced, and its response is consistent with the simulation results. The research results in this paper can provide theoretical support for the study of human-induced vibration of variable section steel truss bridge.

On December 18, 2023, a M_s6.2 earthquake occurred in Jishishan County, Gansu Province, affecting 118 towns including Dahejia Town, Liuji Town and Shiyuan Town. The areas have a relatively low level of economic development, with widespread and severely damaged brick (earth) and wood structures, resulting a significant number of casualties. In view of the large stock of brick-wood buildings in the region and their local characteristics, this study summarizes the architectural and structural characteristics of double-slope brick-wood structures and single-slope high wall brick-wood structures based on the on-site research, analyzes the typical earthquake damage phenomena and mechanisms, discusses the seismic vulnerabilities of existing brick-wood structures, and proposes the corresponding improvement measures in combination with the actual needs of rural construction. The findings indicate that in the epicentral area, most of the brick-wood structures are moderately damaged or severely damaged, and a few are destroyed. Structures with a mix of brick column and earth wall load-bearing and single-slope high-wall structures suffered more severe damage compared to double-slope brick-wood structures. The damage can be classified into four categories including overall or partial collapse, roof damage, wall damage, and other damage. The primary causes of the damage are identified as irrational structural systems, low mortar strength, poor overall integrity, and the absence of effective seismic construction measures. Consequently, this paper suggests targeted improvement measures to enhance the overall integrity, increase the collapse resistance of the walls, and prevent the collapse of roof components. These measures aim to provide a scientific basis and practical guidance for improving the seismic resilience of rural dwellings and optimizing disaster prevention and mitigation strategies.