Seismic Control Research Articles

Research on the effectiveness of a new-type bearing for structural seismic and vibration dual control

The burgeoning expansion of subway systems has heightened the significance of subway-induced vibrations and their impact on nearby structures. Addressing the dual challenges of mitigating subway-induced vibrations and ensuring structural seismic safety is garnering increasing attention. This study introduces a new-type seismic and vibration dual control isolation bearing that leverages the deformability of rubber. This bearing consists of a thick rubber bearing and a traditional horizontal rubber bearing, which are decoupled in motion and responsible for vertical vibration isolation and horizontal seismic isolation, respectively. A scaled model was constructed of an actual structure to assess the effectiveness of this bearing, conducting shaking table tests with inputs simulating typical subway-induced vibrations and seismic motions. Our findings reveal that the bearing successfully meets predefined isolation and vibration control objectives. Regarding subway-induced vibration loads, it markedly diminishes peak vertical acceleration responses. Frequency-wise, it effectively attenuates high-frequency responses while amplifying low-frequency ones. Notably, increasing damping does not significantly improve vertical vibration isolation. Regarding seismic loads, by aptly configuring the horizontal seismic isolation parameters, the bearing achieves targeted seismic isolation objectives. Furthermore, this new bearing demonstrates certain vertical isolation capabilities, distinguishing it from traditional horizontal rubber isolation bearings.

A new constitutive model of shape memory alloy and its seismic mitigation capacity compared with existing models

The existing constitutive models of shape memory alloy (SMA) cannot accurately describe the mechanical behavior in martensitic strengthening segment since their loading and unloading paths in strengthening segment completely overlap. This study proposes a multi-segment linear mathematical model for SMA, which realizes the separation of loading path and unloading path in strengthening segment. A four-story steel frame structure and corresponding braced structures with various SMA constitutive models are designed, and seismic control effects of SMA braces with these models are analyzed and compared through time history analysis. The results show that the sub-cycle unloading mode of SMA constitutive model affects the seismic mitigation capacity of SMA brace in a certain extent. The position of the inflection point of unloading path has very little influence on the structural control ability of SMA braces. The SMA brace using the SMA constitutive model with a single linear sub-cyclic unloading path has the minimal seismic response and the highest seismic reduction ratio. For most evaluation indexes, the seismic mitigation ability calculated by the proposed path separation constitutive model is in the middle of the results calculated by the existing models. SMA models without considering the mechanical behavior of strengthening segment may lead to an erroneous estimation of the energy consumption of SMA brace and the structural damage. The difference of simulation results among various SMA constitutive models is almost independent with ground motion.

Seismic Control of Adjacent Liquid Storage Tanks Based on Vibration Barrier Considering Structure-Soil-Structure Interaction

ABSTRACT A new damping control method for the adjacent liquid storage tanks (LSTs) based on vibration barrier (ViBa) is proposed. Considering liquid-solid-soil coupling and structure-soil-structure interaction, a three-dimensional numerical calculation model is established by ADINA. The seismic control effect of ViBa is investigated, and parametric analysis is carried out. The results show that ViBa has a significant control effect on seismic responses and wave height, and the reduction factor of base shear force reaches the maximum value of 49.26%. The larger the seismic intensity, the liquid storage height and the height-radius ratio, the larger the reduction factor of the ViBa.

Shaking table test study on the seismic control of concrete-filled steel tube arch bridges based on dampers

Shaking table test study on the seismic control of concrete-filled steel tube arch bridges based on dampers

Nonlinear ground acceleration tracking mechanism for seismic control of high-rise buildings considering soil-structure interaction

In this paper, a novel two-step nonlinear ground acceleration feedback mechanism is proposed for vibration mitigation of building structures considering soil-structure interaction. Hence, an observer based receding horizon control (RHC) scheme is presented for active control of the structures. Afterward, a nonlinear two-step auto-regressive framework is appended to the RHC formulations to consider the adaptive seismic term in the resulted control law. Soil-structure interaction (SSI) is also considered in the controller structure regarding soft, medium, and dense soil conditions. A data-driven approach is then introduced for lessening the complexity of the proposed framework for practical applications. A forty-story building equipped with active mass damper (AMD) subjected to earthquake excitations is selected as the numerical study. The superiority of the proposed method is evaluated compared to other control strategies including conventional RHC, ideal RHC, and linear version of the proposed controllers. The outcomes indicate the remarkable accuracy of the proposed method against mentioned control approaches.

Study on Seismic Response Control Methods for Continuous Beam Bridges with Plate Rubber Bearings in Near-Fault Regions

Study on Seismic Response Control Methods for Continuous Beam Bridges with Plate Rubber Bearings in Near-Fault Regions

A Novel Dual Self-Centering Friction Damper for Seismic Responses Control of Steel Frame

Due to their weight, the seismic response control of buildings needs a large-scale damper. To reduce the consumption of shape memory alloys (SMAs), this study proposed a dual self-centering pattern accomplished by the coil springs and SMA, which could drive the energy dissipation device to recenter. Combined with the friction energy dissipation device (FD), the dual self-centering friction damper (D-SCFD) was designed, and the motivation and parameters were described. The mechanical properties of D-SCFD, including the simplified D-SCFD mechanical model, theoretical index calculations of recentering, and energy dissipation performance, were then investigated. The seismic response mitigation of the steel frame adopting the D-SCFDs under consecutive strong earthquakes was finally analyzed. The results showed that a decrease in the consumption of SMA by the dual self-centering pattern was feasible, especially in the case of low demand for the recentering performance. Reducing the D-SCFD’s recentering performance hardly affected the steel frame’s residual inter-story drift ratios when the residual deformation rate was less than 50%, which can help strengthen the controls on the steel frame’s peak seismic responses. It is recommended to utilize the D-SCFD with not too high a recentering performance to mitigate the seismic response of the structure.

Geostatistical seismic inversion and 3D modelling of metric flow units, porosity and permeability in Brazilian presalt reservoir

Flow units (FU) rock typing is a common technique for characterizing reservoir flow behavior, producing reliable porosity and permeability estimation even in complex geological settings. However, the lateral extrapolation of FU away from the well into the whole reservoir grid is commonly a difficult task and using the seismic data as constraints is rarely a subject of study. This paper proposes a workflow to generate numerous possible 3D volumes of flow units, porosity and permeability below the seismic resolution limit, respecting the available seismic data at larger scales. The methodology is used in the Mero Field, a Brazilian presalt carbonate reservoir located in the Santos Basin, who presents a complex and heterogenic geological setting with different sedimentological processes and diagenetic history. We generated metric flow units using the conventional core analysis and transposed to the well log data. Then, given a Markov chain Monte Carlo algorithm, the seismic data and the well log statistics, we simulated acoustic impedance, decametric flow units (DFU), metric flow units (MFU), porosity and permeability volumes in the metric scale. The aim is to estimate a minimum amount of MFU able to calculate realistic scenarios porosity and permeability scenarios, without losing the seismic lateral control. In other words, every porosity and permeability volume simulated produces a synthetic seismic that match the real seismic of the area, even in the metric scale. The achieved 3D results represent a high-resolution fluid flow reservoir modelling considering the lateral control of the seismic during the process and can be directly incorporated in the dynamic characterization workflow.

Negative stiffness and inerter-based dampers: Novel seismic response control approach for base isolated liquid storage tanks

Liquid storage tanks (LSTs) have become indispensable to civil engineering infrastructure. LSTs are used not only for storing harmless fluids but also explosive, toxic, and hazardous substances. Thus, the ability of LSTs to withstand significant seismic activity without damage is a major worry. Strong pulse-type characteristics in near fault (NF) type of ground motions have shown significant base and sloshing displacements for a commonly adopted structural control measure: base isolation (BI). The current study introduces negative stiffness and inerter dampers (NSIDs) as supplemental response control measures to LSTs with BI (BILSTs). Conventional supplemental damping applications in the isolation system are helpful in displacement reduction at the isolator level, but the upper structure response gets severely affected. This study presents NSIDs, characterised by the damping magnification effect, as supplemental dampers to BILSTs. The continuous liquid mass within the tank is represented by discrete lumped masses referred to as sloshing, impulsive, and rigid mass. The stiffness constants of these lumped masses are derived by considering the tank wall and stored liquid physical parameters. The optimal supplemental damping parameters are deduced by developing contour plots describing the sloshing and base displacement response reduction (mitigation) ratios. Through analytical studies conducted using real earthquake records, it has been demonstrated that appropriately designed Negative Stiffness and Inerter Devices (NSIDs) yield enhanced performance for Base Isolated Liquid Storage Tanks (BILSTs). These optimised combinations of NSIDs effectively mitigate isolator displacement, base shear, lumped sloshing mass displacement, and sloshing mass height in response to both near-field (NF) and far-field (FF) base excitations.

Prototype silicone rubber based passive seismic damper: Development, characterization and implementation

Passive damping devices are mostly preferred owing to their relatively lower cost, low maintenance, and stability over a wide range of frequencies during seismic events. Currently, these devices with temperature in-sensitive viscoelastic material are being explored. The paper aims to develop a prototype piston-cylinder based passive damper with silicone rubber particles and characterize it with varied amplitude and frequency of sinusoidal input. The device Silicone Rubber Particle Packed Damper, so developed, was then implemented in the benchmark building for seismic response control. Silicone rubber particles with lower hardness were produced through compressed molding technology to improve the damping efficiency of the device. The device was later converted to an Air Damping Device by removing silicone rubber particles for a natural comparison of efficacy. Hysteresis curves of devices, elliptical in shape, obtained through characterization were mathematically modelled using the Kelvin-Voigt model, and parameters were identified using multivariable linear regression to implement them with the benchmark building. Uncontrolled and controlled responses of benchmark building fitted with, both, damping devices were determined under strong motion (El Centro, Hachinohe) and pulse-type (Kobe, Northridge) seismic excitations. Seismic response parameters; peak displacement, peak interstorey drift, peak acceleration, and peak damper force was estimated. Each seismic response parameter yields substantial reduction for controlled benchmark building with Silicone Rubber Particle Packed Damper. The efficacy of damping devices was established by Performance Indices in terms of peak interstorey ratio, level acceleration, base shear, and control force. Though both passive damping devices were found effective in seismic response control of benchmark building, Silicone Rubber Particle Packed Damper outperforms Air Damping Device. The developed prototype damping devices are a low cost and easy to maintain.

Experimental verification of seismic vibration control of high-rise buildings with friction-type multiple tuned mass dampers

In recent decades, tuned mass damper (TMD) devices have been implemented in numerous high-rise buildings in the world. The vibration of tall buildings caused by natural or man-made dynamic loading poses a challenge. In this study, to ensure structural safety and resident comfort, a friction-type multiple TMD (FT-MTMD) system was investigated and its ability to reduce the seismic response of high-rise buildings was evaluated. The proposed FT-MTMD system comprises multiple TMD units in a parallel arrangement and has a greater frequency bandwidth than a conventional TMD system. To address practical issues, a prototype FT-MTMD system was designed and fabricated to control a scale-down test model which has similar fundamental modal properties to a real 36-story building. Because of the nonlinearity of friction, the parameters of the FT-MTMD system were determined using a proposed optimal design method. First, a component test was conducted to ensure that the parameters of the FT-MTMD agreed with the designed values. Then, the FT-MTMD was installed on the long-period test model and its control performance was experimentally evaluated. Shaking table test results indicated that the FT-MTMD system favorably reduced the seismic response in the test model, indicating that the proposed optimal design method is reliable. A theoretical structure–MTMD model was also developed to simulate the system response with unsynchronized stick-slip motion of the FT-MTMD system. The predicted system response agreed well with the measured response. In addition, to avoid damage to the FT-MTMD system during a severe earthquake, a fail-safe device was employed to lock the TMD when its stroke reached the maximum allowable value.

Seismic performance and damage control of large-span prestressed concrete rigid-frame bridges with high piers crossing strike-slip faults

Post-earthquake surveys show that fault-crossing simply supported beam bridges or continuous beam bridges suffer from severe seismic damage, such as falling beams and even collapse. Currently, there is a lack of understanding of the seismic performance of fault-crossing prestressed concrete rigid-frame bridges (PCRFBs). In this study, a representative PCRFB was used as a case study, and typical strike-slip fault cases were discussed, including fault-crossing angles and permanent displacement. The results revealed that different from other bridge structure types, the mid-span section was prone to yield failure because of the significant plastic deformation demands when the fault crossed the middle span. Positive and negative moment failures of the mid-span girder occurred when the fault-crossing angle was greater than or less than 90°, respectively. The fault-crossing angle is an important factor that affects the seismic performance of PCRFBs. A value of 90° is a favorable fault-crossing angle with minimal damage. The deformation demands of the mid-span were larger than the internal force effects when there was an increase in the permanent ground displacement of the fault. The proposed shock-absorbing hinge system (SAHS) can effectively reduce the vertical displacement of the girder and can significantly avoid the occurrence of plastic hinges, so the main girder is protected.

Совершенствование методов и средств геомеханического мониторинга на основе цифровых технологий

The article discusses methods and technical means of instrumental assessment and control of rockburst hazard and technogenic seismicity during underground mining of ore. It is shown that in conditions of rockburst manifestation and anthropogenic seismicity, complex geomechanical monitoring with the use of a number of complementary methods and technical means is of key importance. The principles of measuring and computing complex construction and organization of integrated monitoring are disclosed using the case of a system created at the geodynamic testing sites of the area of the Streltsovsky and Dalnegorsky ore fields. The features and technical characteristics of measuring as well as software tools included in the monitoring system are listed. Algorithms and software have been developed to filter man-made interference and isolate useful signals, improve the accuracy of location and determination of parameters of acoustically active zones, processing and presentation of monitoring data using modern digital technologies. The scientific and methodological approaches to the study of extremely stressed complex-structured geological environment and the prediction of the hazardous dynamic manifestations of rock pressure in them, including those based on the isolation and parametrization of geomechanical fields and foci of destruction formed in a rockburst hazardous rock mass, are described. The results of complex geomechanical monitoring at a number of rockburst hazardous mines in Russia are presented and the possibility of effective management of rock pressure in rockburst hazardous conditions is shown.

Seismic Behavior of Demountable Reinforced Concrete (RC) Beam-to-Column Joints with Damage-Control Fuses

In this paper, a new type of assembled RC beam–column joint with a beam-end steel cover-plate connection is proposed to achieve seismic toughness and damage control of the joint. Energy-dissipation plates with different structural forms are proposed, and a series of seismic performance indexes of the joints are calculated and analyzed by using the finite element method. The energy-dissipation plate with an arc notch can reach the yield condition faster, and the ultimate bearing capacity of the joint reaches the maximum. The bending design of energy-dissipation plates is carried out by calculating the demand bending moment, and energy-dissipation plates of different structural forms are simulated and verified. The results show that the proposed design formula can ensure that the bending moment at the beam end still maintains elastic deformation when the energy-dissipation plate yields. The important parameters affecting the bending moment of the weakened part in the middle of the energy-dissipation plate are analyzed. Finally, this paper also analyzes the important parameters affecting the seismic performance of the joints. The results show that the seismic performance of the newly assembled RC beam–column joints proposed in this paper is better than that of cast-in-place joints. Increasing the longitudinal reinforcement ratio appropriately can greatly improve the ultimate bearing capacity and ductility of the joints. Increasing the thickness of the energy-dissipation plate, increasing the strength of the energy-dissipation plate, increasing the axial compression ratio of the column, increasing the strength of the concrete, and increasing the strength of the shear web can improve the ultimate bearing capacity of the joints but also reduce their ductility. Under different axial compression ratios, the strain in the core area of the joints is low, and the compressive damage of the concrete is zero, which verifies the effectiveness of the damage-control design of the proposed model.

Автоматизация классификации сейсмических событий при сейсмомониторинге угольной шахты с использованием машинного обучения

The paper is dedicated to the development of an algorithm for automatic classification of geodynamic processes in the context of monitoring seismic activity in mines using machine learning methods. The importance of classifying geodynamic processes is noted in terms of understanding the nature of seismic phenomena, identifying their sources, assessing the potential hazard as well as their impact on the environment and the infrastructure of underground structures. The paper describes an algorithm for analyzing seismic activity based on the data obtained as the result of recording seismic events using the hardware complex and the GITS2 seismic monitoring software in a coal mine. The paper briefly examines the key artificial intelligence methods used to control and predict hazardous geodynamic phenomena. Particular attention is paid to the development of a machine learning model based on decision trees that demonstrates high accuracy in classifying seismic events. The classification accuracy of the developed model is 98,39% on the training set and 98,41% on the test set. This result indicates the high generalization ability of the model on new data and the absence of overfitting. Testing the algorithm on new data entering the system also confirms the high accuracy in classification of seismic event types with the level of 83–93%. This highlights the efficiency of machine learning methods in mine seismic control. After its trial operation, the developed machine learning model will be implemented in the GITS2 monitoring system, that will allow classification of the incoming seismic events in automatic mode.

Research Developments of Eddy Current Dampers for Seismic Vibration Control of Structures

Research Developments of Eddy Current Dampers for Seismic Vibration Control of Structures

Seismic Performance Evaluation of Reinforced Concrete Buildings Retrofitted with a New Concrete Filled Tube Composite Strengthening System

This study proposes a concrete-filled tube composite strengthening system (CCSS), which is a new concept that can improve and supplement the vulnerability of existing CFT seismic strengthening methods. The CCSS seismic reinforcement method is easy to construct and integrates with the existing frame and reinforcement. It is one of the seismic strengthening methods that allows the simple calculation of the required amount of seismic reinforcement and can efficiently increase the strength when applied to existing reinforced concrete (R/C) buildings with non-seismic details dominated by shear failure. To examine the seismic safety of the proposed CCSS, two framework specimens were prepared based on an existing R/C building with non-seismic details. A pseudo-dynamic test was conducted on the unreinforced framework specimen and the framework specimen reinforced with CCSS to verify the seismic strengthening effect of applying CCSS to the existing R/C framework, i.e., in terms of the load–displacement characteristics and seismic response control capability. Based on the pseudo-dynamic test results, restoration of the force characteristics was proposed for the nonlinear dynamic analysis of the building reinforced with CCSS. Nonlinear dynamic analysis was conducted based on the proposed restoration of the force characteristics, and the results were compared with the pseudo-dynamic test results. Finally, for the commercialization of CCSS, nonlinear dynamic analysis was conducted on the existing whole R/C building with non-seismic details that was reinforced with CCSS. The seismic strengthening effect was then verified by examining the seismic response load, displacement characteristics, and the degree of seismic damage to the members based on the ductility ratio before and after seismic strengthening. The study results show that under a design basis earthquake with a magnitude of 200 cm/s2, the unreinforced R/C building exhibits shear failure, and light seismic damage is expected on the CCSS-reinforced building.

Seismic Capacity of R/C Buildings Retrofitted with a V-Bracing System Equipped with a Novel Laterally Layered Friction Damper

This study proposed a novel V-bracing system equipped with a laterally layered friction damper (LLFD), which can supplement the shortcomings of conventional vibration control systems and is applicable to existing reinforced concrete (R/C) buildings. A material test was used to evaluate the material performance and energy dissipation capacity of this LLFD. Pseudo-dynamic testing was conducted on two-story frame specimens based on an existing R/C building with non-seismic details to verify the seismic retrofitting effects of applying the LLFD V-bracing system to existing R/C frames, i.e., the restoring force characteristics, energy dissipation capacity, and seismic response control capacity. Based on the results of the material and pseudo-dynamic tests, restoring characteristics were proposed for the non-linear dynamic analysis of a building (frame specimen) retrofitted with the LLFD V-bracing system. A non-linear dynamic analysis was conducted based on the proposed restoring force characteristics, and the results obtained were compared with the pseudo-dynamic test results. Finally, for evaluating the commercialization potential of the LLFD V-bracing system, a non-linear dynamic analysis was conducted on an existing R/C building with non-seismic details retrofitted with the system. The seismic retrofitting effect was verified by examining the seismic response load and displacement characteristics, energy dissipation capacity, and damper load and displacement response before and after seismic retrofitting. The study results showed that the R/C frame (building) with non-seismic details exhibited shear failure at a design basis earthquake scale of 200 cm/s2; however, light seismic damage could be expected for a frame (building) retrofitted with the LLFD V-bracing system. At a maximum considered earthquake scale of 300 cm/s2, insignificant seismic damage was also anticipated, thereby verifying the validity of the newly developed LLFD V-bracing system.

Seismic isolation effect of tunable friction pendulum system in bridge

ABSTRACT A Tunable Friction Pendulum System (TFPS) was proposed to investigate its seismic isolation control performance in bridge structures. First, the structural design and theoretical model of TFPS are given. Second, the mechanical properties of TFPS are studied through finite element simulation. Then, the above TFPS is introduced into the bridge structure, and the analysis model is established based on SAP2000. Finally, a nonlinear time-history analysis is carried out on the bridge structure, and the seismic isolation performance of TFPS is evaluated by using the dynamic characteristic response index of the bridge structure. Theoretical derivation and finite element analysis results show that TFPS can adjust the dynamic characteristics in real time according to the spectral characteristics of the ground motion input and the response of the structure itself, so that the friction force can be continuously adjusted and energy consumption can be adjusted.

Cyclic loading tests and numerical simulations of an assembled X-shaped flexural steel damper

This paper proposes an assembled X-shaped flexural steel damper. Welding is waived for the novel damper. As the kernel element of the damper, the X-shaped flexural steel plates have the advantages of ease of installation and replacement if necessary. In the analytical part, the effective height of the flexural steel plate was suggested, and then, the yield displacement, yield load and initial stiffness of the damper were derived. The proof-of-concept cyclic loading test was conducted using one reduced-scale specimen within a four-bar linkage experimental setup. The hysteretic performance indexes, including strength, stiffness and energy dissipation, were quantified. The high-fidelity finite element (FE) models were established by ABAQUS. The parametric study was further conducted based on the verified FE model. The considered parameters were the height and thickness of the steel plates. The testing results indicate that the proposed damper has plump hysteretic curve with good energy dissipation capacity and excellent ductility, although slight slip behavior can be found due to the gap caused by the assembling process. The results obtained from analytical method and numerical model are in good agreement with the experimental data. The results of parametric analysis show that the numerical results well agree with analytical predictions, indicating the numerical model can reflect the mechanical behavior of AXSFD. A benchmark frame building was selected to demonstrate the seismic control efficacy of the damper. The nonlinear time history analysis results indicate that the damper reduced both peak and residual interstory drift ratios for the protected structure.