Control Of Engineering Structures Research Articles

Rapid de-stiffening of multilayer transparent structures using controlled thermoplastic softening

Thermoplastic softening is one of the most desirable de-stiffening methods because of its reversibility, scalability, and applicability in many of current multi-layered structures without compromising structural performance. Despite the advantages, long activation times and high activation power requirements are generally considered as the main drawbacks for this method which can potentially limit its application in scenarios where fast de-stiffening is required. The aim of this study is to identify the key design requirements of heating element to minimise the de-stiffening response time using thermoplastic softening while maximising transparency. The focus of this study is on multilayer transparent structures, with low heating element content. A systematic investigation, including experimental and numerical investigation, is performed to study the effect of the fill factor and the heating element’s length scale on the response time of de-stiffening. Melting of the polymer and melting or electrical breakdown of the heating element are observed as practical limitations and are introduced as constraints to the design maps. The fill factor is found to have considerable influence on improving the response time, especially at low fill factors (i.e. below 10%). For the material combinations investigated here, the design maps show that heating elements with wire diameters up to 7 μm, at maximum transparency of 2% fill factor and up to 12 μm at 20% fill factor can achieve sub-second response times for temperature increase of 30 °C. This new understanding will accelerate the technology readiness level of active structural control technology to be used in the future multi-functional and smart structures with a wide range of application in robotics, shape morphing, active damping, and active impact protection.

Seismic Response Control of a Nonlinear Tall Building Under Mainshock–Aftershock Sequences Using Semi-Active Tuned Mass Damper

Under the excitation of strong mainshock (MS), the structure will enter the nonlinear stage, whose hysteretic characteristic can be well-simulated by the Bouc–Wen (BW) model. The accompanying aftershock (AS) may increase structural damage and cause the safety problem, therefore, the advanced structural control technology is worthy of being applied to nonlinear structure under MS–AS sequences. The tuned mass damper (TMD) is a popular vibrational absorber, however, it is sensitive to the frequency deviation and may lose its effect for nonlinear dynamic response control in this issue. To protect the nonlinear tall building under MS–AS sequences effectively, a semi-active TMD (STMD) is investigated in this study, which can vary its frequency and damping in real time simultaneously. It can adapt to structural nonlinear behavior in each time segment through varying its stiffness according to the wavelet transform (WT) based algorithm, and meanwhile, enhance the energy dissipation through switching its damping coefficient in real time. A 10-story nonlinear tall building is proposed as a case study and for comparison, a passive TMD (PTMD) is used. Nine MS–AS sequences are elected and nonlinear structural control performance of STMD is highlighted. Results show that STMD can control structural displacement responses and base shear effectively and performs better than PTMD in reducing the plastic development of the structure as well. Further, energy analysis is proposed and it is verified that STMD has an excellent effect in decreasing the structural input energy from MS–AS sequences and dissipating more energy than PTMD. Especially, it is found that a strong AS may cause a larger response to the nonlinear structure than MS, while the nonlinear control effect of STMD is still significant in that case.

E-Defense Shake Table Experiments Implemented by NIED and Collaborative Research Projects in 2005–2022

The three-dimensional full-scale earthquake testing facility, “E-Defense” was constructed using the 1995 Great Hanshin-Awaji Earthquake as a lesson. Until October 2022, this facility has conducted 123 experiments as part of the research and development on earthquake engineering for various purposes (e.g., the clarification of destruction processes, evaluations of seismic structural performances, functional maintenance, collapse margins, and damage control technologies). Even after its commencement, large earthquakes that significantly affected human life and socioeconomic activities occurred such as the 2011 off the Pacific coast of Tohoku Earthquake caused the Great East Japan Earthquake Disaster. These earthquakes revealed some new challenges for disaster prevention and mitigation. Such issues have also been incorporated as subjects to be addressed by the facility. This article introduces the researches and developments using E-Defense, chronologically linking them with the major earthquakes occurred in Japan after 1995. By summarizing the activities, its near-future direction is also briefly indicated.

Shaking table test study on seismic performance of RC frame structure with NES

A new type of nonlinear vibration absorber NES (Nonlinear Energy Sink) studied in this paper belongs to the structural passive control technology, which consists of a horizontal track and an additional mass block. Acting as a damper absorb and dissipate energy, the NES completes the target energy transfer by generating a horizontal nonlinear restoring force and reduces the response of the main structure. In this paper theoretical analysis of the new NES was analyzed by the expression of the restoring force of the NES and the equation of motion of the additional NES system are deduced. Shaking table test was carried out on the 1:4 scale RC frame structure model installed with the new NES shock absorber, focusing on the research on the energy dissipation and shock absorption effect of the NES shock absorber, and whether it can improve the seismic performance of the RC frame structure damaged in the earthquake. The results show that the NES installed in the RC frame structure has sufficient nonlinear displacement and energy dissipation capacity under the moderate and strong earthquakes, showing a very good energy dissipation and shock absorption effect. The NES can reduce the top story displacement and acceleration response of the main structure under the action of earthquake; the top story displacement and absolute acceleration response are related to the natural frequency of the frame and the spectral characteristics of seismic waves, so that the vibration control effect is affected by the frequency spectrum of seismic waves. In the frequency domain analysis of the frame dynamic response, the nonlinear energy well exhibits the characteristics of broadband control. This type of NES significantly reduces the seismic response of damaged structures, improves the seismic performance of damaged structures under moderate to strong earthquakes, and decreases the risk of potential collapse and construction costs during earthquake aftershocks.

Experimental validation, analytical investigation, and design method of tuned mass damper‐clutching inerter for robust control of structures

AbstractInerters have significantly uplifted the cost‐effectiveness of structural control technologies. A recently proposed tuned mass damper‐clutching inerter (TMDCI) takes advantage of both mass amplification effect and energy absorption capacity of inerter which is more effective and practical than its predecessors. However, the existing study only provided numerical demonstrations while experimental evidence and analytical explanation are still lacking for in‐depth understanding of the dynamic properties and working principles of TMDCIs. In this study, the mathematical descriptions of TMDCIs are first developed and experimentally validated on a three‐story structure. The validated model is then used to analyze the influences of inerter arrangement and total inertance in inerter‐enhanced devices. With an appropriate inerter arrangement and inertance, the TMDCI shows excellent control performance regardless of the changes in the structural frequency. The reason for the strong robustness of TMDCIs is then revealed via analytical investigation of standalone TMDCIs; the harmonically forced steady‐state responses manifest that the TMDCI can be linearized as equivalent tuned mass damper‐inerters with variable parameters whose natural frequency increases with the increase of excitation frequency. Based on the analytical findings, a design method with robustness consideration is subsequently proposed and draws satisfactory TMDCI designs for both single‐degree‐of‐freedom and multi‐degree‐of‐freedom structures. The designed TMDCI outperforms the comparable devices for both impulsive and seismic response mitigation. The study provides analytical insight into the control capacity of TMDCIs and lays the groundwork for practical design of TMDCIs as an effective and robust control strategy for engineering structures.

Analysis on the Mechanical Properties of Viscoelastic Damper and Its Application in Construction Engineering

With the deepening of the structural vibration control technology and theory, all kinds of energy dissipation and vibration reduction equipment have been more and more used in engineering. Using SAP2000 software, the elastic-plastic time period before and after the installation of viscoelastic damper is calculated, and it is compared, which provides a useful example for the future application in high-rise buildings.

Quasihexagonal Platinum Nanodendrites Decorated over CoS2 -N-Doped Reduced Graphene Oxide for Electro-Oxidation of C1-, C2-, and C3-Type Alcohols.

The development of efficient and highly durable materials for renewable energy conversion devices is crucial to the future of clean energy demand. Herein, cage‐like quasihexagonal structured platinum nanodendrites decorated over the transition metal chalcogenide core (CoS2)‐N‐doped graphene oxide (PtNDs@CoS2‐NrGO) through optimized shape engineering and structural control technology are fabricated. The prepared electrocatalyst of PtNDs@CoS2‐NrGO is effectively used as anodic catalyst for alcohol oxidation in direct liquid alcohol fuel cells. Notably, the prepared PtNDs@CoS2‐NrGO exhibits superior electrocatalytic performance toward alcohol oxidation with higher oxidation peak current densities of 491.31, 440.25, and 438.12 mA mgpt –1 for (methanol) C1, (ethylene glycol) C2, and (glycerol) C3 fuel electrolytes, respectively, as compared to state‐of‐the‐art Pt‐C in acidic medium. The electro‐oxidation durability of PtNDs@CoS2‐NrGO is investigated through cyclic voltammetry and chronoamperometry tests, which demonstrate excellent stability of the electrocatalyst toward various alcohols. Furthermore, the surface and adsorption energies of PtNDs and CoS2 are calculated using density functional theory along with the detailed bonding analysis. Overall, the obtained results emphasize the advances in effective precious material utilization and fabricating techniques of active electrocatalysts for direct alcohol oxidation fuel cell applications.

Fixed and Base Isolated Framed Structures: A Comparative Study

Necessity of constructing multi-storied buildings is increasing these days. But they are more prone to severe damage due to earthquakes. Base isolation is one of the most powerful tools pertaining to the passive structural vibration control technologies. The structure above the ground, is separated from the effects of earthquake forces by introducing a mechanism that helps the structure to hover. This project deals with analysis of 10 storey RCC, Steel and Composite structures of different shapes with and without base isolation in various seismic zones by Response Spectrum Method using ETABS software. Lead rubber bearings designed as per UBC97 was used for base isolation. Plus shape was found to be most suitable for base isolation for RC structure, whereas for steel and composite structures rectangular and hollow shapes were found suitable. It was also observed that concrete structure performs best when base isolated, compared to other structures.

Integrating structural control, health monitoring, and energy harvesting for smart cities

AbstractCities that are adopting innovative and technology‐driven solutions to improve the city's efficiency are considered smart cities. With the increased attention on smart cities with self‐driving vehicles, drones, and robots, designing smart infrastructure is only a natural extension. Smart infrastructures aim to self‐diagnose, self‐power, self‐adapt, and self‐heal during normal and extreme operating conditions. Structural vibration control (SVC) and structural health monitoring (SHM) technologies, in particular, are expected to play pivotal roles in the development of modern smart and resilient structures. SVC methodologies intend to provide supplemental damping and reduce the structural dynamic responses during normal and extreme events. SHM methodologies offer valuable information about the structure's condition that is useful for maintenance purposes and rapid damage detection in post‐hazard events. The collapse of the 12‐story Champlain Towers South, a beachfront condominium in the Miami suburb of Surfside, Florida, could have been known in advance with an embedded SHM technology. More recently, the integrated structural control and health monitoring (ISCHM) systems have shown promise in the development of smart cities of the future. The integrated architecture incorporates the control and health monitoring components as complementary technologies and simultaneously takes advantage of both technologies. This article provides a state‐of‐the‐art review of ISCHM ideas and systems. It presents recent significant developments in structural control, SHM, and energy harvesting that are paving the way towards the advent of integrated ISCHM systems, including damage‐tolerant control systems. This article also identifies future promising research areas for designing the next generation of autonomous ISCHM systems for smart cities.

PERFORMANCE OF SEISMICALLY ISOLATED BUILDINGS USING SFP BEARING: AN APPLICATION IN VIETNAM

At present, the use of structural vibration control technology in the design of earthquake resistant in Vietnam is very limited. In this paper, a performance evaluation of using single friction pendulum bearing (SFP) for earthquake resistant buildings with earthquake conditions in Vietnam is presented. A one-dimensional (1-D) model of a 5-storey building subjected to earthquakes was developed for time history analysis. Accordingly, the model is analyzed in two configurations: with and without SFP bearing. The ground acceleration data was selected and scaled to fit the design acceleration in Hanoi determined from TCVN 9386:2012. The dynamic responses of the two configurations was evaluated in detail. It is shown that the seismically isolated configuration can reduce the base shear up to 90%. A significant decrease in the inter-story drift and absolute floor acceleration was also observed.

A comparative study on the effectiveness of bidirectional and tridirectional isolation systems used in large-scale single-layer lattice domes during earthquakes

To improve the structural seismic performance, structural vibration control technology is widely introduced into building structures. In terms of base isolation, both bidirectional and tridirectional isolation systems are usually used in large-scale domes. However, the difference in the isolation performance between the two systems needs to be evaluated and further understood. In this paper, large-scale single-layer lattice domes with bidirectional and tridirectional isolation systems are investigated and compared under near-field and far-field ground motions. The dynamic demands of isolated structures are quantified, and the isolation effectiveness of different isolation systems is evaluated. The effects of the near-field and far-field ground motions on isolated structures are compared. The seismic performance of isolated structures is analyzed based on incremental dynamic analysis (IDA). In addition, a parametric study is performed to discuss the effect of the damping coefficient of the damper in the tridirectional isolation system on the isolation effectiveness. It is found that from a statistical point of view, both the bidirectional and tridirectional isolation systems are able to reduce the dynamic demands of domes during earthquakes, while the tridirectional isolation system has better suppression effectiveness for dynamic demands; the near-field earthquake ground motions have a more obvious influence on isolated structures than the far-field earthquake ground motions. For the tridirectional isolation system, a larger damping coefficient may not necessarily be able to obtain better isolation effectiveness in structures. This study provides a basis for improving the understanding of the isolation effectiveness of different isolation systems used in large-scale domes.

Mechanism and control of the long-term performance evolution of structures

It is well known that structural properties degrade under long-term environmental exposure and loading and that the degradation rate is controlled by inherent physical and chemical degradation mechanisms. The elucidation of the degradation mechanisms and the realization of effective long-term performance degradation control have been a research frontier in the field of civil engineering in recent years. Currently, the major topics that concern this research frontier include revealing the physical and chemical mechanisms of structural performance evolution under long-term environmental exposure and loading and developing structural performance degradation control technologies based on fiber-reinforced materials, for example, fiber-reinforced polymers (FRPs) and fabric-reinforced cementitious matrix (FRCM). In addition, there are novel structural performance control technologies, such as using a shape memory alloy (SMA) and self-healing concrete. This paper presents a brief state-of-the-art review of this topic, and it is expected to provide a reference for subsequent research.

Numerical Simulation of Reinforced Soil Slope in Subgrade Widening of Expressway

The finite difference element software FLAC3D was used to simulate the reconstruction and expansion project of Xinle-Yuanshi expressway. The model of reinforced soil slope widening subgrade was established. Based on the comparison of the simulation data of the sections with different heights and structural forms, the structural behavior of reinforced soil structure in subgrade widening project was analyzed. The law of structural deformation and construction control technology were summarized.

Research on Structural Seismic and Vibration Control Technology of Modern Buildings

In recent years, the overall development of China’s construction industry has been relatively good, but due to the continuous improvement of people’s daily life quality, the requirements for building structures have become higher and higher. This paper analyzes the structural earthquake resistance of modern buildings and the application of corresponding vibration control technology, and analyzes the specific application of vibration isolation and control technology to provide effective guarantee for the stability of modern building structures.

Revealing the Linear and Nonlinear Dynamic Behaviors of Metabeams With a Dynamic Homogenization Model

Abstract Metastructures can be designed to exhibit extraordinary properties and thus are widely applicable in various fields, such as vibration suppression, wave control, and energy harvesting. In the present work, a dynamic homogenization model is strictly derived for a metabeam (a beam with periodic resonators) by using the asymptotic homogenization method. The homogenization model is validated via comparing the vibration frequencies and associated vibration modes of the metabeam predicted by the present model with exact ones, and it is then used to analyze the linear (or nonlinear) vibration responses of the metabeam subject to a harmonic excitation with a small- (or large-) amplitude. Furthermore, the effect of periodic resonators on the vibration suppression performance of the metabeam is discussed. It is demonstrated that such kind of dynamic homogenization model is of great convenience to predict the vibration responses of metastructures besides the widely studied dispersion relation. Thus, it is expected to be useful for the vibration suppression and control of engineering structures.

Recent research and development of structural control in Japan

AbstractIn Japan, structural control is widely recognized as a fundamental technology for exceeding the performance limitations of conventional earthquake/wind‐resistant buildings. Over the last three decades, research and development (R & D) has been implemented in construction, mechanical industries, and universities. Additionally, many types of control strategies have been proposed through theoretical, experimental, and numerical investigations. In comparison with other countries, Japan has successfully and rapidly developed remarkable engineering applications for actual buildings using advanced structural control technologies, because Japanese construction companies promote R & D in cooperation with mechanical industries, structural design offices, and universities. This review paper introduces the recent structural control advances in Japan. The state‐of‐the‐art report is based on papers published by the Architectural Institute of Japan, the Proceedings of the 16th World Conference on Earthquake Engineering, articles published in a structural engineering magazine, the special theme sessions at the 7th World Conference on Structural Control and Monitoring, and other relevant information. The key research directions are the simplification of control laws and mechanical devices, high performance with either little or no energy supply, device magnification, use of structural frames and substructures, new materials, adaptability, and cautious uses serving various purposes.

Vibration Control Performance Analysis and Shake‐Table Test of a Pounding Tuned Rotary Mass Damper under the Earthquake

The voided biaxial concrete slab has been widely used in the engineering field. The slab has become a popular choice for designers and architects looking to reduce slab thickness and overall structure weight recently. Utilizing the empty space in the voided slab and introducing the structural control technology of mass damper into it, a new pounding tuned rotary mass damper (PTRMD) is proposed in this paper. This damper is designed to locate in the prefabricated hollow module to mitigate response of structure subject to disastrous excitations. The damper combines the characteristics of pounding mechanisms (PMDs) and tuned rotary mass dampers (TRMDs). This is achieved by a ball rolling on a curved orbit and a fixed stroke‐limiting plate. The structural control performance of the PTRMD is studied numerically and verified experimentally. Specifically, first, the motion equations for a single‐degree‐of‐freedom (SDOF) and multiple‐degree‐of‐freedom (MDOF) system with PTRMDs are derived. Furthermore, numerical results show that the PTRMD provides significant energy dissipation, and thus, is quite effective in reducing the structure response. Besides, the PTRMD generally exhibits better control performance and robustness in terms of vibration suppression compared with the TRMD proposed by the authors before. Finally, a shake‐table test is conducted to verify the damping effect of a PTRMD‐controlled SDOF system. Pertinent results confirm the effectiveness and robustness of PTRMDs for structural control.

Multistorey Residential Building with Base Isolation Method Using SAP

Residential homes are of exceptional significance after any natural calamity which encompass earthquake. The structural and non-structural additives need to stay operational and secure after earthquake. So you can mitigate the impact of earthquake at the structure the bottom isolation method is the splendid opportunity as a seismic protecting system. The primary concept of base isolation gadget is to lessen the earthquake brought on inertia forces by using growing the fundamental length of the structure. Base isolation is one of the most effective tools of engineering concerning the passive structural vibration control technologies. It is supposed to allow a building or non-building shape to continue to exist a probably devastating seismic impact thru a right preliminary design or next changes. In some instances, software of base isolation can improve each a structure's performance and its seismic sustainability notably. he behaviour of multi-storey building of ordinary and abnormal configuration beneath earth quake is complex and it varies of wind masses are assumed to behave concurrently with earth quake loads. On this paper a residential of multi-storey constructing is studied for earth quake with base isolation approach using SAP 2000.

Performance of Single Friction Pendulum bearing for isolated buildings subjected to seismic actions in Vietnam

Using structural control technology in earthquake resistant design of buildings in Vietnam is very limited. In this paper, a performance evaluation of using Single Friction Pendulum (SFP) bearing for seismically isolated buildings with earthquake conditions in Vietnam is presented. A two-dimensional (2-D) model of the 5-storey building subjected to earthquakes is analyzed in time domain. Accordingly, the model is analyzed for 2 cases: with and without SFP bearing. The ground acceleration data is selected and scaled to suit the design acceleration in Hanoi followed by the Standard TCVN 9386:2012. It is shown that the seismically isolated buildings gets the performance objectives while achieving an 91% reduction in the base shear, a significant decrease in the inter-story drift and absolute acceleration of each story. A post-publication change was made to this article on 9 Jul 2020 to remove an author.

Partial pole assignment with time delays for asymmetric systems

Considering both single and multiple time delays, partial pole assignment for stabilising asymmetric systems is exemplified by friction-induced vibration and aerodynamic flutter. The control strategy is a single-input state feedback including constant time delays in the feedback loop. An unobservability condition is considered to assign some poles while keeping others unchanged. The receptance method is applied to avoid modelling errors from evaluating mass, damping and stiffness matrices by the finite element method. The solution is formulated in linear equations which allow determination of control gains. The stability of the closed-loop system is analysed by evaluating the first few dominant poles and determining a critical time delay. The numerical study shows that the proposed method is capable of making partial pole assignment with time delays. Since many structures and systems with non-conservative forces can be represented by asymmetric systems, this approach is widely applicable for vibration control of engineering structures.