Resettable Device Research Articles

Vibration control of structures against near‐field earthquakes by using a novel hydro‐pneumatic semi‐active resettable device

Vibration control of structures against near‐field earthquakes by using a novel hydro‐pneumatic semi‐active resettable device

Resettable‐inertance inerter: A semiactive control device for energy absorption

Semiactive control systems are based on formerly passive mechanical devices whose characteristics are adjusted in real time by active means. They can be classified into variable-damping dampers, variable-stiffness springs, and variable-inertance inerters. Similarly to the case of “variable-stiffness,” two possibilities are devised for inerters: “independently-variable inertance,” where inertance can increase or decrease continuously at any instant of time, and “resettable-inertance,” where it can increase only at instants where relative velocity is zero. By duality with resettable-stiffness springs, a resettable-inertance inerter (RII) is composed of an inerter that can suddenly be disconnected from the vibrating system and blocked in order to eliminate kinetic energy. Studies on “independently-variable inertance” have been carried out recently, but there are still no studies on “resettable inertance.” This paper presents an analytical numerical study on RII, for an energy-based control law, through the mathematical model of a mechanical implementation. By simulation of a numerical example that considers a SDOF system with three different devices, the performance is demonstrated for energy absorption and vibration reduction. Moreover, closed-form expressions for the equivalent-linear inertance, stiffness, and damping are found for the resettable devices and validated through the numerical example. Main conclusion is that RII adds equivalent damping without dynamically stiffening the structure. Besides, the absorbed energy can be dissipated and/or harvested in time intervals in which the RII is uncoupled from the structure.

烟箱盖板支撑复位装置

烟箱盖板支撑复位装置

Analog active valve control design for non-linear semi-active resetable devices

Semi-active devices use the building's own motion to produce resistive forces and are thus strictly dissipative and require little power. Devices that independently control the binary open/closed valve state can enable novel device hysteresis loops that were not previously possible. However, some device hysteresis loops cannot be obtained without active analog valve control allowing slower, controlled release of stored energy, and is presents an ongoing limitation in obtaining the full range of possibilities offered by these devices. This in silico study develops a proportional-derivative feedback control law using a validated nonlinear device model to track an ideal diamond-shaped force-displacement response profile using active analog valve control. It is validated by comparison to the ideal shape for both sinusoidal and random seismic input motions. Structural application specific spectral analysis compares the performance for the non-linear, actively controlled case to those obtained with an ideal, linear model to validate that the potential performance will be retained when considering realistic nonlinear behaviour and the designed valve control approach. Results show tracking of the device force-displacement loop to within 3-5% of the desired ideal curve. Valve delay, rather than control law design, is the primary limiting factor, and analysis indicates a ratio of valve delay to structural period must be 1/10 or smaller to ensure adequate tracking, relating valve performance to structural period and overall device performance under control. Overall, the results show that active analog feedback control of energy release in these devices can significantly increase the range of resetable, valve-controlled semi-active device performance and hysteresis loops, in turn increasing their performance envelop and application space.

Effectiveness of resettable energy dissipating devices in seismic response modification of elastic SDoF systems

SummarySemi‐active variable stiffness resettable devices can reduce seismic demands and damages in structures. Despite their advantages, variable stiffness resettable devices are under‐utilized mainly because of the shortage of fundamental research in quantifying the sensitivity of key seismic response parameters, and losses, in structures that use such systems for seismic hazard mitigation. Within this setting, the research summarized herein measures the effectiveness of semi‐active resettable energy dissipating devices in the Single‐Degree‐of‐Freedom domain aiming at quantifying the sensitivity of their seismic response to variation in control parameters and generating the required knowledge to utilize such semi‐active devices in the Multi‐Degree‐of‐Freedom domain. The performance (i.e. maximum relative displacement and peak absolute acceleration demands) of Single‐Degree‐of‐Freedom systems with an array of semi‐active control logics under various dynamic excitation regimes is studied. Two sets of 40 ground motions representing various seismic loading conditions (i.e. pulse‐like and rock‐site ground motions) are used, and an efficient control logic for mitigating these seismic demands is proposed. Numerical results show that proposed control logic enables a decrease of 40–60% for both maximum relative displacement and seismic base shear and 15–25% decrease for peak absolute acceleration. Copyright © 2016 John Wiley & Sons, Ltd.

Aseismic smart building isolation systems under multi-level earthquake excitations: Part I, conceptual design and nonlinear analysis

As a novel structural control strategy, tuned mass damper (TMD) inspired passive and semi-active smart building isolation systems are suggested to reduce structural response and thus mitigate structural damage due to earthquake excitations. The isolated structure’s upper stories can be utilized as a large scaled TMD, and the isolation layer, as a core design point, between the separated upper and lower stories entails the insertion of rubber bearings and (i) viscous dampers (passive) or (ii) resettable devices (semi-active). The seismic performance of the suggested isolation systems are investigated for 12-story reinforced concrete moment resisting frames modeled as “10 + 2” stories and “8 + 4” stories. Passive viscous damper or semi-active resettable devices are parametrically evaluated through the optimal design principle of a large mass ratio TMD. Statistical performance metrics are presented for 30 earthquake records from the three suites of the SAC project. Based on nonlinear structural models, including P-delta effects and modified Takeda hysteresis, the inelastic time history analyses are conducted to compute the seismic performances across a wide range of seismic hazard intensities. Results show that semi-active smart building isolation systems can effectively manage seismic response for multi-degree-of freedom (MDOF) systems across a broader range of ground motions in comparison to uncontrolled case and passive solution.

Aseismic smart building isolation systems under multi-level earthquake excitations: Part II, energy-dissipation and damage reduction

Based on the performance results of the previously suggested smart building isolation systems (1st companion paper), this following study verifies the control effects of the systems from the view point of energy dissipation and damage level metrics. Several different model cases of the strategically isolated multi-story building structures utilizing passive dampers and semi-active resettable devices are analyzed and the energy-based target indices are compared. Performance comparisons are conducted on statistically calculated story/structural hysteretic energy and story/structural damage demands over realistic suites of earthquake ground motion records, representing seismic excitations of specific return period probability. Again, the semi-active solutions show significant promise for applications of resettable device, offering advantages over passive systems in the consistent damage reductions. The specific results of this study include the identification of differences in the mechanisms by which smart building isolation systems remove energy, based on the differences in the devices used. Less variability is also seen for the semi-active isolation systems, indicating an increased robustness.

English

An intelligent device advanced Vigilance control device in train loco is used to check the alertness of the loco pilot. It is the Microcontroller based multi -resettable device which is used to monitor the loco pilot’s action. This device is used to apply the emergency brake automatically by cyclically generating the warning signals. It reduces the error caused by the loco pilot if the driver is unconscious, dead or fast asleep and ensures the safety to the passengers by automatically stopping the train. It stores the actions carried out by the loco pilot periodically which can be used as the reference to find out the courses of action done by the pilot. The information during the events can be used for future analysis. This paper also informs the position of the loco mob to the higher authorities and tracks the position of the train where it is stopped by using Global System for Mobile communication (GSM) and Global Positioning System (GPS) technologies.

The Application of Resettable Device to Semi-Active Tuned Mass Damper Building Systems for Multi-level Seismic Hazard Mitigation

An innovative multi-story Semi-Active Tuned Mass Damper (SATMD) building system is proposed to control seismic response of existing structures. The application of adding new stories as large tuned mass and semi-active (SA) resettable actuators as central features of the control scheme is derived. For the effective control of the structures, the optimal tuning parameters are considered for the large mass ratio, for which a previously proposed equation is used and the practical optimal stiffness is allocated to the actuator stiffness and rubber bearing stiffness. A two-degree-of freedom (2-DOF) model is adopted to verify the principal efficiency of the suggested structural control concept. The simulations for this study utilizes the three ground motions, from SAC project, having probability of exceedance of 50% in 50 years, 10% in 50 years, and 2% in 50 years for the Los Angeles region. 12-story moment resisting frames, which are modified as '12+2' and '12+4' story structures, are investigated to assess the viability and effectiveness of the system that aims to reduce the response of the buildings to earthquakes. The control ability of the SATMD scheme is compared to that of an uncontrolled and an ideal Passive Tuned Mass Damper (PTMD) building system. From the performance results of suggested '12+2' and '12+4' story retrofitting case studies, SATMD systems shows significant promise for application of structural control where extra stories might be added.

Failure Causes of a Polymer Resettable Circuit Protection Device

As a circuit protection device, failure or abnormal behavior of polymer positive-temperature-coefficient resettable devices can cause damage to circuits. Identification of failure modes and determination of failure causes are necessary to improve the reliability of resettable circuit protection devices and understand their limitations. In this study, a series of experiments was conducted to identify the failure modes of polymer positive-temperature- coefficient resettable circuit protection devices. The causes of failures of a polymer positive-temperature-coefficient resettable circuit protection device were determined by failure analyses, including analysis of the increase in surface temperature using an infrared camera, interconnection analysis using cross-sectioning and environmental scanning electron microscopy, analysis of the microstructures of carbon-black-filled polymer composite, thermal property analysis of the polymer composite, and coefficient of thermal expansion analysis of different parts of the resettable circuit protection device.

Anomaly Detection of Polymer Resettable Circuit Protection Devices

As circuit protection devices, failure or abnormal behavior of polymer positive-temperature-coefficient resettable devices can cause damage to circuits. It is necessary to detect anomalies in the resettable circuit protection devices to provide early warning of failure and avoid damage to a circuit. In this paper, a novel anomaly detection method, the cross-validation-based sequential probability ratio test, is developed and applied to the failure precursor parameters of the resettable circuit protection devices to conduct anomaly detection. The cross-validation-based sequential probability ratio test integrates the advantages of both the sequential probability ratio test for in situ anomaly detection and the cross-validation technique for model parameter selection to reduce the probability of false and missed alarms in anomaly detection. The cross-validation-based sequential probability ratio test solves the model parameter selection difficulty of the traditional sequential probability ratio test and improves its performance in anomaly detection.

Nonlinear design and sizing of semi-active resetable dampers for seismic performance

Semi-active resetable devices can be used in a wide range of structures to reduce damage due to seismic loading. The specific benefits of these devices in reducing displacement, base shear, or both have been illustrated using linear and experimentally validated nonlinear device models, as well as in a range of large to full scale experiments. However, designing the specific device dimensions to obtain a specific device force-displacement capacity and response is difficult and no set design approach exists. More importantly, there is no design approach for specifying device dimensions to both meet a desired force-displacement capacity and linear or near linear device hysteresis loop shape.In this research a design procedure is developed and presented by example that allows an device dimensions to be sized so that its response approximates the desired ideal linear responses and the desired force or stiffness (force-displacement) capacity. This method is validated by systematically by comparing device designs with equivalent ideal linear models to assess how well they meet design goals, using an experimentally validated nonlinear model. Methods are presented for the most common device control laws in terms of the basic device dimensions. Errors were generally less than 10%. The overall approach is seen to deliver the device dimensions for a highly linear device response that meets design specifications, and is the first generalised design approach presented for these semi-active resetable devices or any similar semi-active device.

Development and spectral analysis of an advanced diamond shaped resetable device control law

Passive energy dissipation has advantages such as low cost, easily predictable response, and ease of implementation, which can be offset by difficulty tuning or designing the devices for optimum behaviour over a range of inputs and responses. Recent research into semi-active energy dissipations systems has highlighted their ability to customise response and provide a control input that is adaptive to the structural response without requiring excessive energy input. In some specialised cases, specific control laws have been designed that reduce displacement and structural force, while simultaneously reducing the total base-shear transmitted to the foundation from both structural column forces and damping forces. These significant advantages can be offset by the limited energy dissipation that can arise as a result of the specific device control laws and hysteresis loops used.This research focuses on a more effective resetable device control law called the “diamond control law”, for its unique semi-actively enabled device hysteresis loop, which maximises energy dissipation while simultaneously minimising the impact on base shear forces. It achieves this affect by controlling the release of stored energy in the resetable device – smart dissipation in place of maximum or instantaneous uncontrolled release typically used in such devices. A spectral analysis shows that this new an approach enables a decrease of 30–40% for both displacement and structural force, which is equivalent to 15–20% critical viscous damping for an uncontrolled base structure. The total base shear is also decreased by 40%, which has significant potential benefits for retrofit applications. This level of displacement and base shear reductions was not available (in combination) from prior resetable device control approaches, and thus represents a significant expansion of the design space and capability for these semi-active devices.

Spectral analysis for a semi-active-passive net-zero base-shear design concept

SUMMARY Passive high force-to-volume (HF2V) dampers offer significant displacement reduction and energy dissipation, but cannot customise overall response. Semi-active resettable devices offer adaptive, custom hysteresis loops that reduce displacement and base shear, but have limited dissipation. This paper presents a new, combined concept to maximise displacement reduction without increasing base shear – a net-zero base-shear concept. HF2V devices, up to a maximum of 10% structural weight, are combined with fixed stiffness resettable devices. Spectral analyses are run for the three SAC ground motion suites that iteratively size the HF2V device at each structural period to achieve maximum displacement reductions without increasing median base shear. HF2V velocity dependence and the need to scale HF2V capacity to spectral velocity are examined in terms of their impact on the results of these analyses. The net-zero approach reduces base shear by up to 50% and displacements by 30–70% over all ground motions, exceeding reductions obtained by either device separately by 30–50% (relative). The net-zero condition is not reached within the device limits defined, except at relatively long periods (>3.5 s) because of a virtuous circle of reduced displacement from the resettable and HF2V devices outweighing the increased base shear from the HF2V devices alone. These results are independent of HF2V device scaling, design and velocity dependence. The overall net-zero concept offers a significant advantage in a combination that cannot be achieved by passive or semi-active solutions alone. Copyright © 2011 John Wiley & Sons, Ltd.

Using upper storeys as semi-active tuned mass damper building systems

This paper presents an exploratory case study based analysis of the seismic performance of multi-storey passive and semi-active tuned mass damper (PTMD and SATMD) building systems are investigated for 12-storey moment resisting frames modelled as ‘10+2’ storey and ‘8+4’ storey. Segmented upper stories of the structure are isolated as a tuned mass, and a passive viscous damper or semi-active resetable device is adopted for energy dissipation. Optimum TMD control parameters and appropriate matching SATMD configurations are adopted from a companion study on a simplified two degree of freedom (2-DOF) system. Log-normal statistical performance results are presented for 30 probabilistically scaled earthquake records. The time history analysis and normalised reduction factor results show the response reductions for all seismic hazards. Thus, large SATMD systems can effectively manage seismic response for multi degree of freedom (MDOF) systems across a broad range of ground motions in comparison to passive solutions. This research demonstrates the validity of the TMD building systems for consideration in future design and construction. It also provides a template for the design and analysis of passive or semi-active TMD buildings utilising large masses, or more efficiently, added storys, for improving seismic response performance.

Customising semi-active resetable device behaviour for abating seismic structural response

Semi-active resetable actuators have been shown to be capable of significantly improving seismic structural response and customising structural hysteresis loops to reduce both displacement and base shear demands. Hence, device behaviour and dynamics can be tailored to the application. However, the maximum forces produced, in particular with air as the working fluid, can be a limiting factor to avoid extreme device sizes. This investigation incorporates an actively controlled (stored) high-pressure air source to enhance the capabilities of such resetable devices. The devices are designed using a validated non-linear model incorporating the dynamics and non-linearities of the working fluid, valves, sensor lags and computational limitations. Initial simulations show 100-600% increases in the peak device forces, with 100% obtained when the initial pressure is doubled. In addition, the high pressure source allows greater manipulation of the device behaviour and response. This additional flexibility enables, for example, devices that are more resistant or resist differently in opposing directions. The impact of device enhancements over standard resetable devices is then demonstrated experimentally. This paper extends these novel resetable devices to create more flexible and actively controlled devices for semi-active structural control. Finally, a “net-zero base shear design” concept is presented, where the added damping reaction forces are exactly offset by structural response reductions to give large displacement reductions with no overall change to base shear forces – maximising control with no impact on the foundations.

Semi‐active tuned mass damper building systems: Application

AbstractSeismic performance attributes of multi‐story passive and semi‐active tuned mass damper (PTMD and SATMD) building systems are investigated for 12‐story moment resisting frames modeled as ‘10+2’ stories and ‘8+4’ stories. Segmented upper portion of the stories are isolated as a tuned mass, and a passive viscous damper or semi‐active resetable device is adopted as energy dissipation strategy. The semi‐active approach uses feedback control to alter or manipulate the reaction forces, effectively re‐tuning the system depending on the structural response. Optimum tuned mass damper control parameters and appropriate matching SATMD configurations are adopted from a companion study on a simplified two‐degree‐of‐freedom system. Statistical performance metrics are presented for 30 probabilistically scaled earthquake records from the SAC project. Time history analyses are used to compute response reduction factors across a wide range of seismic hazard intensities. Results show that large SATMD systems can effectively manage seismic response for multi‐degree‐of freedom systems across a broad range of ground motions in comparison to passive solutions. Specific results include the identification of differences in the mechanisms by which SATMD and PTMD systems remove energy, based on the differences in the devices used. Additionally, variability is seen to be tighter for the SATMD systems across the suites of ground motions used, indicating a more robust control system. While the overall efficacy of the concept is shown the major issues, such as isolation layer displacement, are discussed in detail not available in simplified spectral analyses, providing further insight into the dynamics of these issues for these systems. Copyright © 2009 John Wiley & Sons, Ltd.

Semi‐active tuned mass damper building systems: Design

AbstractPassive and semi‐active tuned mass damper (PTMD and SATMD) building systems are proposed to mitigate structural response due to seismic loads. The structure's upper portion self plays a role either as a tuned mass passive damper or a semi‐active resetable device is adopted as a control feature for the PTMD, creating a SATMD system. Two‐degree‐of‐freedom analytical studies are employed to design the prototype structural system, specify its element characteristics and effectiveness for seismic responses, including defining the resetable device dynamics. The optimal parameters are derived for the large mass ratio by numerical analysis. For the SATMD building system the stiffness of the resetable device design is combined with rubber bearing stiffness. From parametric studies, effective practical control schemes can be derived for the SATMD system. To verify the principal efficacy of the conceptual system, the controlled system response is compared with the response spectrum of the earthquake suites used. The control ability of the SATMD scheme is compared with that of an uncontrolled (No TMD) and an ideal PTMD building systems for multi‐level seismic intensity. Copyright © 2009 John Wiley & Sons, Ltd.

Experimental validation of semi‐active resetable actuators in a ⅕th scale test structure

AbstractThe seismic performance of a test structure fitted with semi‐active resetable devices is experimentally investigated. Shaking table tests are conducted on a ⅕th scale four‐storey building using 27 earthquake records at different intensity scalings. Different resetable device control laws result in unique hysteretic responses from the devices and thus the structure. This device adaptability enables manipulation or sculpting of the overall hysteresis response of the structure to address specific structural cases and types. The response metrics are presented as maximum 3rd floor acceleration and displacement, and the total base shear. The devices reduce all the response metrics compared with the uncontrolled case and a fail‐safe surrogate. Cumulative probability functions allow comparison between different control laws and additionally allow tradeoffs in design to be rapidly assessed. Ease of changing the control law in real‐time during an earthquake record further improves the adaptability of the system to obtain the optimum device response for the input motion and structural type. The findings are an important step to realizing full‐scale structural control with customized semi‐active hysteretic behaviour using these novel resetable device designs. Copyright © 2008 John Wiley & Sons, Ltd.

Nonlinear models and validation for resetable device design and enhanced force capacity

Resetable devices are a novel semi-active approach to managing structural response energy. Recently developed devices allow independent control of each chamber enabling unique approaches to sculpting the structural hysteresis loops and behaviour. This paper creates a nonlinear model of experimental prototypes, which is fully generalizable, and does so in a step-by-step manner adding each nonlinear affect individually. Nonlinearities that can significantly affect the performance, including valve size, mass flow rate and friction, are characterized experimentally and modelled. The results are validated against experimental data for cases of all forms of device control as well as for cases utilizing external pressurized sources to enhance the force capacity. Final model results are within 5% of nonlinear experimental data showing a strong correlation between the fundamental nonlinear dynamics of the model and the experimental devices. The overall results and approach are fully general for application to the design or analysis of these semi-active device systems using either hydraulic fluids or, as in this case, air for the working medium. Copyright © 2008 John Wiley & Sons, Ltd.