Agathoklis Giaralis

• Dipl.-Eng, MSc, PhD, FHEA, CEng, M.ASCE
• Associate Professor at Khalifa University

The increase in the intensity and frequency of extreme events have underscored the critical need for resilient structures that can sustain minimal damage and can be quickly recovered. This Mini symposium aims to consolidate and disseminate innovative research and practical approaches to for damage assesment, control and rapid recovery to enhance th...

This paper addresses the optimal tuning and numerical performance assessment of regenerative tuned mass damper inerters (RE-TMDIs) in three different configurations with non-grounded inerters attached to cantilevered primary structures under Gaussian white noise base excitation. The studied RE-TMDI configurations behave linearly and differ in the p...

Irwin surface wind sensor is widely used in the wind tunnel testing for the studies of urban and environmental aerodynamics. However, conventional physics-based calibration of this sensor leads to decreased measurement accuracy in regions with low flow velocities and high turbulence intensity. To address this issue, this study proposes a novel phys...

This paper examines the vibration response of the steel-concrete composite Ultra Shallow Floor Beam (USFB ® ) flooring system which incorporates asymmetric steel perforated beams to accommodate the concrete floor slab within the depth of the flanges while allowing reinforcement and/or service ducts to pass through the web openings. This is a lightw...

8 This paper conceptualizes a novel passive vibration control system comprising a tuned mass damper inerter 9 (TMDI) contained within a seismically isolated rooftop and investigates numerically its effectiveness for seismic 10 response mitigation of building structures. The working principle of the proposed isolated rooftop tuned mass 11 damper ine...

The tuned inerter damper (TID) has recently emerged in the literature as a bona fide resonant vibration absorber for the seismic protection of building structures by relaxing the requirement for large secondary mass employed by conventional tuned mass dampers (TMDs). This is achieved by leveraging the inertia property of lightweight inerter devices...

The increasing rate of urbanization in recent decades has resulted in a global surge in the construction of slender high-rise buildings. These structures are prone to excessive wind-induced lateral vibrations in the crosswind direction owing to vortex shedding effects, causing occupant discomfort and, ultimately, dynamic serviceability failure. To...

The design of seismic protective devices (SPDs), such as fluid viscous dampers (VDs), and inertial vibration absorbers (IVAs), requires the adoption of appropriate models for: (i) the earthquake excitation description (e.g. stochastic stationary/non-stationary versus recorded ground motions); (ii) the seismic structural response estimation (e.g. li...

Preface for the special issue on Advances on Inerter-based Seismic Protection of Structures. Bulletin of Earthquake Engineering

In recent years, the tuned mass damper inerter (TMDI) has been demonstrated in several theoretical studies to be an effective vibration absorber for the seismic protection of non-isolated buildings. Its effectiveness relies on careful tuning of the TMDI stiffness and damping properties, while its performance improves with the increase of the inerta...

Recently, the passive tuned mass damper inerter (TMDI) has been widely considered in the literature to protect structures from earthquakes. Its effectiveness relies on careful design/tuning of the TMDI stiffness and damping properties, while its performance improves with the increase of the inertance property which is readily scalable. Nevertheless...

In recent years, the passive tuned mass damper inerter (TMDI) has been widely considered in the literature for the seismic demand mitigation of building structures. Its effectiveness relies on careful design/tuning of the TMDI stiffness and damping properties, while its performance improves with the increase of the inertance property, which is read...

In recent years, the potential of various lightweight inerter-based dynamic vibration absorbers, including tuned inerter dampers (TIDs), for improving the serviceability occupant comfort in wind-excited slender/tall buildings under aerodynamic vortex shedding (VS) effects has been demonstrated in the literature. This is achieved through efficient m...

In recent years, the passive tuned mass damper inerter (TMDI) has been widely considered for mitigating crosswind floor accelerations causing occupant discomfort in tall slender buildings. Its effectiveness relies on careful design/tuning of the TMDI stiffness and damping properties which entails large number of floor acceleration evaluations for w...

In recent decades, the increasing rate of urbanisation has seen an upturn in the construction of tall slender buildings in all major cities worldwide. These structures have low resonant frequencies and inherent damping, which make them particularly susceptible to wind-borne vibrations in the crosswind direction due to vortex shedding (VS) effects....

In recent decades, active vibration control of buildings for earthquake-induced damage mitigation has been widely considered in the scientific literature. Fuzzy logic control (FLC) has been shown to be an effective approach to regulate control forces exerted by actuators to building structures to reduce earthquake-borne oscillations. In many cases,...

Inerter-based vibration absorbers (IVAs), such as the tuned-mass-damper-inerter (TMDI), have become popular in recent years for the earthquake protection of building structures. Previous studies using linear structural models have shown that IVAs can achieve enhanced vibration suppression, but at the expense of increased control forces exerted from...

In this paper, optimum design of engineering problems is considered by means of the Atomic Orbital Search (AOS), a recently proposed metaheuristic optimization algorithm. The algorithm is inspired by the quantum-based atomic model. In particular, the mathematical development of the algorithm is based on principles of quantum mechanics focusing on t...

In recent years, inerter vibration absorbers (IVAs), such as the tuned mass damper inerter (TMDI), attracted much attention in the literature for reducing seismic displacement demands of base isolated structures (BISs). Several theoretical studies reported reduced BIS seismic demands with increasing inertance endowed by a grounded inerter element b...

The Sendai Framework for Disaster Risk Reduction 2015-2030 (SFDRR) highlights the importance of scientific research, supporting the ‘availability and application of science and technology to decision making’ in disaster risk reduction (DRR). Science and technology can play a crucial role in the world’s ability to reduce casualties, physical damage,...

The tuned mass-damper-inerter (TMDI) is a linear passive dynamic vibration absorber widely considered in the literature to mitigate the motion of dynamically excited primary structures. Previous studies focused on optimal TMDI tuning approaches and connectivity arrangements to improve motion control efficiency for some given primary structure. This...

This special issue of the ASCE-ASME Journal of Risk and Uncertainty in Engineering Systems: Part B comprises 10 papers related to recent advances and emerging approaches on response analysis and optimization of energy harvesting dynamic systems in presence of uncertainties. A concerted effort was made to achieve broad geographic representation, whi...

A local structural modification, namely top-storey softening, is herein considered in conjunction with optimally tuned top-floor tuned mass damper inerter (TMDI) for improved serviceability performance in mid-to-high rise buildings (host structures). The focus is to reduce floor accelerations on typical core-frame host structures with rectangular f...

The tuned mass‐damper‐inerter (TMDI) is a linear passive dynamic vibration absorber for motion control of dynamically excited building (primary) structures. It couples the classical tuned mass damper (TMD), comprising a secondary mass attached to the top building floor via a spring and dashpot, with an inerter, a mechanical element resisting relati...

This paper examines the performance of a regenerative dynamic vibration absorber, dubbed energy harvesting-enabled tuned mass-damper-inerter (EH-TMDI), for simultaneous vibration suppression and energy harvesting in white noise excited damped linear primary structures. Single-degree-of-freedom (SDOF) structures under force and base excitations are...

An innovative structural modification, top-storey softening, is herein proposed in conjunction with optimally tuned top-floor tuned mass damper inerter (TMDI) for improved serviceability performance in typical core-frame slender buildings with rectangular floor plan susceptible to wind-induced vortex shedding (VS) effects causing occupant discomfor...

This paper considers a novel shaking table testing campaign to assess the tuned mass-damper-inerter (TMDI) vibrations suppression attributes in harmonically excited structures under the combined effect of nonlinear structural response and nonlinear inerter device behavior deviating from the ideal linear inerter element developing acceleration-depen...

This paper presents preliminary experimental results from a novel shaking table testing campaign investigating the dynamic response of a two-degree-of-freedom (2DOF) physical specimen with a grounded inerter under harmonic base excitation and contributes a nonlinear dynamic model capturing the behavior of the test specimen. The latter consists of a...

Motivated by practical needs to reduce data transmission payloads in wireless sensors for vibration-based monitoring of engineering structures, this paper proposes a novel approach for identifying resonant frequencies of white-noise excited structures using acceleration measurements acquired at rates significantly below the Nyquist rate. The approa...

The tuned mass-damper-inerter (TMDI) couples the classical tuned mass-damper (TMD), with an inerter device developing a resisting force proportional to the relative acceleration of its ends by the "inertance" constant. Previous works demonstrated that the inclusion of the TMDI leads to more efficient broadband vibration control for a range of diffe...

The Vibrating Barrier (ViBa) is a large-scale oscillating mass-spring-damper unit contained in the ground and tuned to mitigate the motion of surrounding structures under earthquake-induced ground shaking, without being directly in contact to them, through a structure-soil-structure interaction mechanism. Previous research showed that ViBa achieves...

The tuned-mass-damper-inerter (TMDI) is a linear passive dynamic vibration absorber for the seismic protection of buildings. It couples the tuned-mass-damper (TMD), comprising an oscillatory secondary mass installed at top building floor via a spring and a damper, with an inerter device developing acceleration-dependent resisting force. In the TMDI...

Seismically excited adjacent buildings with equal floor heights and with inadequate clearance may interact/collide due to out of phase response developing slab-to-slab pounding forces which, although do not induce local damage to structural members, they do influence the overall seismic structural response. Herein, a numerical study is undertaken t...

The consideration of wireless acceleration sensors is highly promising for cost-effective output-only system identification in the context of operational modal analysis (OMA) of large-scale civil structures as they alleviate the need for wiring. However, practical monitoring implementations for OMA using wireless units suffer a number of drawbacks...

The data file contains peak factor spectra compatible with Eurocode 8 response spectrum for different damping ratios as plotted in Figure 5 of the paper: "Giaralis A and Spanos PD. (2012). Derivation of response spectrum compatible non-stationary stochastic processes relying on Monte Carlo peak factor estimation. Earthquakes and Structures, 3: 581-...

This paper investigates numerically the potential of ground floor linear tuned inerter damper (TID) to mitigate floor acceleration causing occupants' discomfort in wind-excited multi-storey buildings due to vortex shedding (VS) effects while generating electric energy. To this aim, TID stiffness and damping properties were optimally designed to min...

This is an extended abstract of the work reported in: Taflanidis A.A., A. Giaralis, D. Patsialis. (2019). Multi-objective optimal design of inerter-based vibration absorbers for earthquake protection of multi-storey building structures. Journal of the Franklin Institute, https://doi.org/10.1016/j.jfranklin.2019.02.022

This is an extended abstract of the work: Savvidis R., D. Pachakis, A. Giaralis. (2019). A real options approach to facilitate decisions on the timing of seismic retrofit/upgrade in seaports with increasing throughput demand. ASCE-ASME Journal of Risk and Uncertainty in Engineering systems, Part A: Civil Engineering, 5: 04018048.

In this paper, the concept of an ideal grounded linear inerter, endowing supplemental inertia to passive linear tuned mass-dampers (TMDs) through its inertance property without increasing the TMD mass, is considered to reduce lateral displacement demands in base isolated structural systems (BISs). Optimal tuned mass-damper-inerter (TMDI) design par...

In recent years different inerter-based vibration absorbers (IVAs) emerged for the earthquake protection of building structures coupling viscous and tuned-mass dampers with an inerter device. In the three most popular IVAs the inerter is functioning either as a motion amplifier [tuned-viscous-mass-damper (TVMD) configuration], mass amplifier [tuned...

A novel multi-sensor power spectrum blind sampling (PSBS) approach is proposed supporting low-power wireless sensor networks (WSN) for Operational Modal Analysis (OMA) applications. The developed approach relies on arrays of wireless sensors, employing deterministic non-uniform in time multi-coset sampling to acquire structural response acceleratio...

9 A real options (RO) formulation is proposed for decision-making on the timing to upgrade the seismic performance of 10 existing seaports with increasing throughput demand in earthquake prone areas. The pay-off of the seismic upgrade 11 investment option is estimated based on projected net earnings, repair cost, and downtime for a damaging referen...

This paper investigates the potential of tuned mass dampers (TMDs) coupled with inerter devices in different tuned mass dampers inerter (TMDI) topologies to dissipate oscillations in tall buildings due to vortex shedding in the across wind direction while generating electric energy. The TMDI is first optimized for minimizing peak accelerations for...

The tuned mass-damper-inerter (TMDI) is a recently proposed passive vibration suppression device that couples the classical tuned mass-damper (TMD), comprising a secondary mass attached to the structure via a spring and dashpot, with an inerter. The latter is a two-terminal mechanical device developing a resisting force proportional to the relative...

This paper contributes a pioneering numerical study to assess statistically, within the performance based earthquake engineering framework, the effect of the evolutionary frequency content observed in field recorded earthquake induced ground motions (GMs) to peak seismic structural response of yielding multi-degree-of-freedom structures. To this ai...

The recently proposed by the first two authors Vibrating Barrier (ViBa) can be interpreted as a large-scale linear mass-damper unit buried in the ground and tuned/designed to protect surrounding structures without being directly in contact to them through a structure-soil-structure interaction mechanism. Previous research demonstrated that ViBa ach...

This paper contributes a novel numerical study to assess the potential of the two most widely used modal-strain based damage indices for damage detection in structural components under flexure for post-earthquake damage characterization of reinforced concrete multi-storey planar frame buildings. To this aim, buildings are treated as transversely vi...

Motivated by practical needs to reduce data transmission payloads in wireless sensors for vibration-based monitoring of civil engineering structures, this paper proposes a novel approach for identifying resonant frequencies of white-noise excited structures using acceleration measurements acquired at rates significantly below the Nyquist rate. The...

A probabilistic framework for the cost-effective design of supplemental seismic protective devices considering multiple criteria related to their life-cycle performance is reviewed in this contribution. The framework relies on time-history analysis for describing structural behavior, on an assembly-based vulnerability approach for quantifying earth...

A robust control technique is proposed to regulate the current and angular velocity in typical brushless direct current (BLDC) motors. The proposed technique relies on two degree-of-freedom (2-DOF) H infinity control with loop shaping in which the structure of the two controllers and the loop shaping function are pre-specified parametrically (i.e.,...

This is an invited keynote presentation. Vibration-based health monitoring (VHM) techniques are commonly considered for non-destructive condition assessment, design verification, and damage detection in civil engineering structures. They rely on acquiring and processing response acceleration signals from vibrating structures excited by ambient (e....

This paper proposes a novel computationally economical stochastic dynamics framework to estimate the peak inelastic response of yielding structures modelled as nonlinear multi degree-of-freedom (DOF) systems subject to a given linear response spectrum defined for different damping ratios. This is accomplished without undertaking nonlinear response...

This paper assesses two different approaches for efficient output-only Vibration-based Structural Health Monitoring (V-SHM) in large-scale civil engineering structures, promoting the use of dense arrays of low-power wireless sensors. Firstly, a non-uniform deterministic sub-Nyquist multi-coset sampling scheme is considered to acquire ambient statio...

The tuned mass-damper-inerter (TMDI) is a recently proposed linear passive dynamic vibration absorber for the seismic protection of buildings. It couples the classical tuned mass damper (TMD) with an inerter, a two-terminal device resisting the relative acceleration of its terminals, in judicial topologies, achieving mass-amplification and higher-m...

In this paper, the classical linear tuned mass damper (TMD) is coupled with an inerter, a two-terminal device resisting the relative acceleration of its terminals, in various tuned mass-damper-inerter (TMDI) topologies to suppress excessive wind-induced oscillations in tall buildings causing occupant discomfort. A parametric numerical study is unde...

This article assesses numerically the potential of two different spectral estimation approaches supporting non-uniform-in-time data sampling at sub-Nyquist average rates (i.e. below the Nyquist frequency) to reduce data transmission payloads in wireless sensor networks for operational modal analysis of civil engineering structures. This considerati...

An efficient nonlinear stochastic dynamics methodology has been developed for estimating the peak inelastic response of hysteretic multi-degree-of-freedom (MDOF) structural systems subject to seismic excitations specified via a given uniform hazard spectrum (UHS), without the need of undertaking computationally demanding non-linear response time-hi...

In this paper the tuned mass-damper-inerter(TMDI)is considered for passive vibration control and energy harvesting in harmonically excited structures. The TMDI couples the classical tuned mass-damper (TMD) with a grounded inerter: a two-terminal linear device resisting the relative acceleration of its terminalsby a constant of proportionality terme...

Motivated by a need to reduce energy consumption in wireless sensors used for Vibration-based Structural Health Monitoring (V-SHM) in seismically prone areas, this paper explores the potential of a recently established sampling scheme, termed co-prime sampling, in conjunction with the multiple signal classification (MUSIC) pseudo-spectrum for earth...

A non-stationary stochastic averaging/linearization formulation is considered in conjunction with a phenomenological stochastic model for pulse-like ground motions (PLGMs) to probe into the response of bilinear hysteretic strain hardening oscillators to typical near-source accelerograms with forward-directivity signatures without resorting to non-l...

In recent decades, the concept of the passive linear tuned mass-damper (TMD) has been considered as a valid option for vibration suppression of dynamically excited building structures due to its relatively simple design and practical implementation. Conceptually, the TMD comprises a mass attached to the structure whose vibration motion is to be con...

Optimally designed tuned mass-damper-inerters (TMDIs) are considered to meet code-prescribed serviceability criteria in typical wind-excited tall buildings subject to vortex shedding effects in a performance-based design context. The TMDI, couples the classical tuned-mass-damper (TMD) with an inerter, a two-terminal device resisting the relative ac...

This chapter provides a concise qualitative overview of the philosophy for earthquake resistant design of ordinary structures adopted by relevant international codes of practice, including Eurocode 8. The aim is to facilitate practicing engineers with the interpretation of the code-prescribed design objectives and requirements for the seismic desig...

This chapter delineates all the required computational and logical steps involved in the analysis stage of seismic design of ordinary reinforced concrete (r/c) buildings according to Eurocode 8 (EC8) by means of detailed self-contained flowcharts and pertinent comments. Special focus is given to verification checks for structural regularity in plan...

A novel dynamic vibration absorber (DVA) configuration is introduced for simultaneous vibration suppression and energy harvesting from oscillations typically exhibited by large-scale low-frequency engineering structures and structural components. The proposed configuration, termed energy harvesting-enabled tuned mass-damper-inerter (EH-TMDI) compri...

In this paper, the effectiveness of the tuned mass-damper-inerter (TMDI) vis-à-vis the classical tuned mass-damper (TMD) is assessed to suppress vortex shedding induced vibrations to tall building structures in the across-wind direction. The TMDI, previously proposed in the literature to mitigate earthquake-induced vibrations in multi-storey buildi...

This paper considers a reliability-based approach for the optimal design of the tuned mass-damper-inerter (TMDI) in linear building frames with uncertain structural properties subject to seismic excitations defined as stationary colored random processes with uncertain parameters. The TMDI is a recently introduced generalization of the classical lin...

In this paper the potential of a novel dynamic vibration absorber termed energy harvesting-enabled tuned mass-damper-inerter (EH-TMDI) is assessed for simultaneous vibration suppression and power generation in white-noise force-and base acceleration-excited structures modelled as damped single-degree-of-freedom (SDOF) oscillators. The considered EH...

In this paper the performance of a compressive sensing (CS)-based vis-à-vis a power spectrum blind sampling (PSBS)-based spectral estimation approach is numerically assessed in undertaking operational modal analysis (OMA) using the frequency domain decomposition algorithm. The examined approaches consider response acceleration measurements sampled...

This paper explores the practical benefits of the recently proposed by the authors tuned mass-damper-inerter (TMDI) visà- vis the classical tuned mass-damper (TMD) for the passive vibration control of seismically excited linearly building structures assumed to respond linearly. Special attention is focused on showcasing that the TMDI requires consi...

Motivated by a need to reduce energy consumption in wireless sensors for vibration-based structural health monitoring (SHM) associated with data acquisition and transmission, this paper puts forth a novel approach for undertaking operational modal analysis (OMA) and damage localization relying on compressed vibrations measurements sampled at rates...

A novel numerical study is undertaken to assess the influence of the frequency domain (FD) attributes of wavelet analysis filter banks for vibration-based structural damage detection and localization using the relative wavelet entropy (RWE): a damage-sensitive index derived by wavelet transforming linear response acceleration signals from a healthy...

This chapter presents three numerical benchmark example problems considering three different structures to illustrate the implementation of various clauses of Eurocode 8 (EC8) for the seismic design of ordinary reinforced concrete (r/c) buildings. Pertinent numerical input data and selected output data are reported in tabular form to facilitate the...

This chapter provides practical recommendations for the preliminary seismic design and the finite element modeling of reinforced concrete (r/c) building structures assumed to behave linearly. It also discusses and provides commentary on structural seismic analysis methods adopted by Eurocode 8 (EC8). Specifically, the main principles of conceptual...

This book aims to serve as an essential reference to facilitate civil engineers involved in the design of new conventional (ordinary) reinforced concrete (R/C) buildings regulated by the current European EC8 (EN 1998-1:2004) and EC2 (EN 1992-1-1:2004) codes of practice. The book provides unique step-by-step flowcharts which take the reader through...

This book aims to serve as an essential reference to facilitate civil engineers involved in the design of new conventional (ordinary) reinforced concrete (R/C) buildings regulated by the current European EC8 (EN 1998-1:2004) and EC2 (EN 1992-1-1:2004) codes of practice. The book provides unique step-by-step flowcharts which take the reader through...

A real options approach is proposed to facilitate decision-making on the appropriate time to upgrade the seismic performance of existing seaports in earthquake prone areas within a time frame of 10 to 15 years. The considered time frame is dictated by commonly required investments for expanding the capacity of contemporary seaports to meet the ever...

Operational modal analysis (OMA) is a widely used construction verification and structural health monitoring technique aiming to obtain the modal properties of vibrating civil engineering structures subject to ambient dynamic loads by collecting and processing structural response acceleration signals. Motivated by the need for cost-efficient OMA us...

The time-dependent wavelet-based mean instantaneous period (MIP) is used as a numerical tool to characterize the time-varying frequency content of typical far-field recorded earthquake ground motions (GMs) and to probe into the hysteretic response of reinforced concrete (r/c) yielding structures. It is shown that the MIP captures well the temporal...

The reliability based optimal design is considered of tuned mass-damper-inerter (TMDI) equipped linear building frames subject to seismic excitations modeled as stationary colored random processes. The TMDI is a recently introduced generalization of the classical linear tuned mass-damper (TMD) benefitting from the mass amplification property, the s...

A stochastic averaging approach is used in conjunction with non-stationary response spectrum compatible random processes to derive time-varying effective linear properties (ELPs), namely damping ratio and natural frequency, for bilinear hysteretic oscillators subject to seismic excitation specified by an elastic response spectrum. It is shown numer...

The presentation reviews briefly standard compressive sensing based techniques for operational modal analysis available at the time of the presentation and introduces the power spectral blind sampling technique providing some preliminary numerical results. More details on the method and comprehensive numerical results are found in: Gkoktsi K and G...

An overview and discussion of the latest, at that time, developments on intensity measures (IMs) and scaling procedures for recorded ground motions used in performance-based seismic assessment of structures is provided.

Motivated by the need to reduce monetary and energy consumption costs of wireless sensor networks in undertaking output-only/operational modal analysis of engineering structures, this paper considers a multi-coset analog-Toinformation converter for structural system identification from acceleration response signals of white noise excited linear dam...

This special issue of the International Journal of Sustainable Materials and Structural Systems (IJSMSS) aims to present recent advances and emerging cross-disciplinary approaches in the broad field of structural health monitoring (SHM) with a focus on novel techniques and applications for data acquisition and processing, uncertainty modelling and...

Wavelet analysis of vibration signals measured by sensors placed on dynamically excited linear structures has proved to be an effective tool for detection and localization of structural damage. Recently, it has been shown that the relative wavelet entropy (RWE) computed from signal energy-preserving wavelet coefficients of vibration signals from "h...

Recently, the so-called tuned mass-damper-inerter (TMDI) system has been introduced by the authors for the passive vibration suppression of multi degree-of-freedom structures exposed to broadband and to narrowband stochastic base-excitations. The TMDI is a generalization of the well-known and widely used in various passive vibration control applica...

A novel scaling algorithm for ground motion accelerograms (GMs) is proposed in support of incremental dynamic analysis used to establish dependable statistical relationships between scalable intensity measures (IMs) and engineering demand parameters (EDPs) within a performance-based earthquake engineering framework. Specifically, an iterative harmo...

In this paper a compressive sensing (CS), sub-Nyquist, non-uniform deterministic sampling technique is considered in conjunction with a computationally efficient power spectrum estimation approach for frequency domain output-only system identification of linear white noise excited structural systems. The adopted CS sensing spectral estimation appro...

This paper proposes a novel passive vibration control configuration, namely the tuned mass-damper-inerter (TMDI), introduced as a generalization of the classical tuned mass-damper (TMD), to suppress the oscillatory motion of stochastically support excited mechanical cascaded (chain-like) systems. The TMDI takes advantage of the “mass amplification...