Time History Response Research Articles

NON-STATIONARY RESPONSE ANALYSIS OF A HIGH-RISE BUILDING IN HAIKOU DURING TYPHOONS

From 2014 to 2016, several wind resistant field measurements were conducted to the high-rise building in Haikou. Based on these measurements, the present paper disclosed the characteristics of the time-history responses of axial acceleration on different floors during four typhoons, including the Rammasun, Kalmaegi, Mujigae and Sarika typhoons. The modal parameters of the measured building were identified by Morlet time-frequency wavelet transform methods, and the amplitude-dependent modal damping ratios and frequencies along translational directions were investigated. The results show that the variation trend of modal frequency with acceleration amplitude identified by the Morlet wavelet is the same as that recognized by time-domain method, while it is scattered with the interval bar (min-average-max) due to the nonstationary response of typhoon. Meanwhile, the larger the amplitude of acceleration response of high-rise buildings under strong wind, the greater the time-varying fluctuation of modal parameters identified by wavelet transform, and the bigger the difference between the interval bar (min-average-max). The full-scale study is expected to provide useful information on the wind-resistant design of high-rise buildings in typhoon-prone regions.

Nanoscale flow-induced nonlinear vibration of multilayer graphene based-resonators: Slip and transition flow regimes

This paper presents a nanoscale fluid-structure interaction (FSI) model for flow-induced nonlinear vibration of multilayer graphene based-resonators in the slip and transition regimes. Based on the multibeam interlayer shear model with von Kármán geometric nonlinearity and nonlocal modified couple stress theory, the size-dependent equations of motion are obtained for beam resonators laminated of NG-graphene layer and (NG−1) interlayer crosslinks. The small-scale effect on effective viscosity and slip boundary conditions of nanoscale flow is formulated by introducing the average velocity correction factor. For unbounded and bounded (by a rigid wall) nanoflows, the closed-form expressions of velocity correction factor in terms of Knudsen number, as a dimensionless discriminant parameter, are developed to correct the pressure distribution predicted by the potential theory. The present FSI model considers the size effects through the length scale parameter for microstructure local rotation, the nonlocal parameter for long-range interatomic interactions, and Knudsen number for slip condition of nanoscale flow. The Galerkin's method in conjunction with the multiple-scale perturbation technique is used to obtain closed-form solutions of frequency ratio and time-history response. The natural frequencies of cantilever multilayer graphene nanostrips are validated with the ones existing in the literature. Parametric studies are carried out to investigate the influences of small-scale, number of layers, interlayer shear modulus, and fluid characteristics on the linear and nonlinear natural frequencies. Findings show that the critical upstream speed for dynamic instability of the coupled system can change considerably by taking into account the size effects of nanoflow and nanostructures. Therefore, the classical FSI model is inadequate for analyzing nanoscale flow-induced vibration of nanoresonators. Also, it is seen that the effect of geometric nonlinearity becomes very significant for multilayer graphene beams with small interlayer shear modulus.

Free and Forced Vibration Behaviors of Magnetodielectric Effect in Magnetorheological Elastomers

This paper is concerned with the free and forced vibration responses of a magneto/electroactive dielectric elastomer, emphasizing the chaotic phenomena. The dielectric elastomers under external magnetic and electrical excitations undergo large elastic deformation. The magnetodielectric elastomer is modeled based on the Gent–Gent strain energy function to incorporate the influence of the second invariant and the strain stiffening. The viscoelasticity of the active polymer is also considered in the form of Rayleigh’s dissipation function. The equation of motion is governed with the aid of the Lagrangian equation in terms of a physical quantity, namely, the stretch of the elastomer. An energy-based approach is utilized to re-evaluate the static and DC voltage instabilities of the resonator. Time-stretch response (time history behavior), phase plane diagram, Poincaré map, and fast Fourier transform are numerically obtained and presented to explore the chaotic oscillation behavior of the active polymer actuators. The results reveal that the magnetic field may tune the stability and instability regions of the active polymeric membrane. It has also been shown that the applied magnetic field may lead to chaotic vibration responses when a sinusoidal voltage is applied simultaneously to the system. The results presented in this paper can be effectively used to design magnetic and electrical soft robotic actuators and elastomer membranes under electrical and magnetic stimulants.

Dynamic stability of single-layer spherical reticulated shell structures under earthquake action

In past decade, earthquake disasters have seriously damaged nonstructural components, so it is very important to study their dynamic stability. However, the existing researches mainly focus on the dynamic stability of multistory and high-rise buildings, and there are still deficiencies in the analysis of dynamic stability of reticulated shell structures under earthquake action. This paper takes the 40 m span K8 single-layer spherical reticulated shell structure with practical engineering significance as the research object, we study its dynamic instability characteristics under earthquake action, and propose a dynamic stability judgment method. The influence of various parameters on the critical loads of emotional stability of reticulated shell structures is systematically analyzed, including the impact of horizontal seismic action, the vertical seismic activity, and the three-dimensional seismic movement, considering the influence of material elastoplasticity; the result of different seismic inputs, the effects of initial geometric imperfections; the effects of varying rise span-ratio. In this paper, to investigate the nonlinear time-history response analysis, we uses the finite-element package ABAQUS. We first analyze the rise-span ratio as the dynamic stability of 1/3 single-layer reticulated shell structure under the action of the El Centro (1940) earthquake to reveal the dynamic loss of reticulated shell structure under earthquake action stable feature. The practical method for determining the proposed dynamic stability has a clear physical meaning and a range of applications. Our findings highlight that the critical load for dynamic stability under horizontal earthquake action is significantly lower than vertical earthquake action, and the critical load is the lowest under three-dimensional earthquake action. Material elastoplasticity influences the critical loads for dynamic stability of reticulated shell structures under different ground motions. The critical load of dynamic stability of single-layer structures with a larger rise-span ratio is lower, while those with a smaller one is higher. The initial geometric defects of the structure should be considered in practical engineering applications. The reticulated shell structure with a larger rise-span ratio needs to consider the dynamic stability problem in the strong earthquake area.

RELIABILITY-BASED ROBUST DESIGN OPTIMIZATION FOR BUILDING-CONNECTING INERTIAL-MASS DAMPER

In this paper, we propose an accurate and efficient reliability evaluation method for robust design optimization using a probabilistic approach. First, we verify the validity of this method using two benchmark functions. Then, we apply this method to the robust design optimization problem of building-connecting damper parameters and verify the effect of robust design. We consider the variation of the natural period and structural damping ratio of buildings, and directly evaluate the criteria satisfaction rate (CSR) using the response value calculated by time-history response analysis.

Viscoelastic Effects on the Nonlinear Oscillations of Hard-Magnetic Soft Actuators

AbstractThe hard-magnetic soft materials (HMSMs) belong to the magnetoactive category of smart polymers that undergo large actuation strain under an externally applied magnetic field and can sustain a high residual magnetic flux density. Because of these remarkable characteristics, HMSMs are promising candidates for the remotely controlled actuators. The magnetic actuation behavior of the hard-magnetic soft actuators (HMSAs) is considerably affected by the viscoelastic material behavior of HMSMs. In this article, we aim at developing an analytical dynamic model of a typical planar model of HMSAs concerning the viscoelasticity of HMSMs. A Zener rheological model in conjunction with an incompressible neo-Hookean model of hyperelasticity and Rayleigh dissipation function is employed for defining the constitutive behavior of the viscoelastic HMSA. The governing equations of dynamic motion are deduced by implementing the nonconservative form of the Euler–Lagrange equation. The established dynamic model is utilized for providing preliminary insights pertaining to the effect of the viscoelasticity on the nonlinear oscillations of the actuator. The phase–plane portraits, Poincaré maps, and the time–history response are plotted to investigate the stability, resonant behavior, and periodicity of the actuator. The results and inferences reported here should provide the initial step toward the design and the development of modern actuators for diverse futuristic applications in the medical and engineering fields.

Simplified BEM-based mathematical model for bottom-hinged oscillating wave surge converters under large-amplitude regular waves

The linear relationship between wave amplitude and wave torque based on the boundary element method (BEM) is widely employed for small-amplitude waves. However, linear relationships are unsuitable for bottom-hinged oscillating wave surge converters (OWSCs) under high waves owing to nonlinearities, such as wave overtopping. This paper presents an improved BEM introducing an incident wave amplitude correcting factor to simplify the complex nonlinearities under high regular waves. The correcting factors were calibrated with computational fluid dynamics (CFD) using OpenFOAM. An Oyster 800-like OWSC was adopted as the study model. A quadratic fitting curve of correcting factor vs. wave height is applicable because the calibrated correcting factors significantly correlate with wave heights but are almost irrelevant to wave periods. Though the time–history responses differ in BEM and CFD under high waves, BEM-based time-averaged results show good accuracy and high computational efficiency, such as equivalent pitch amplitude and capture width ratio (CWR). At mid-low periods, simultaneously varying power take-off (PTO) stiffness and damping than solely varying PTO damping, significantly increases CWR, especially under low waves. The capturing power under high waves substantially increases because of pitch motion amplification. At long periods, adjusting PTO inertia produces negligible efficiency improvement even with amplified oscillation.

Study on Phase Characteristics of Wind Pressure Fields around a Prism Using Complex Proper Orthogonal Decomposition

Wind loads for the design of wind-resistant high-rise buildings are generally evaluated based on spectral modal analysis or time-history response analysis using wind pressure data obtained from wind tunnel experiments with rigid models. The characteristics of the fluctuating wind pressures around vibrating buildings must be evaluated for relevant wind-resistant designs because the wind pressures around buildings are affected by their vibrations. One of the methods to investigate fluctuating fields is complex proper orthogonal decomposition (CPOD), which can express complicated pressure fields, including advection phenomena, as coherent structures. This paper presents the phase characteristics of fluctuating wind pressures around rigid and elastic models of a square-sectioned prism evaluated via CPOD analysis using the results of wind tunnel experiments. The evaluation procedure for the symmetricity of the fluctuating wind pressure modes obtained via CPOD is presented. The similarity of fluctuating wind pressure fields is evaluated as the congruency of the planes formed by the 1st- and 2nd-eigenmodes. With symmetricity and similarity, the fluctuating wind pressure fields are classified into three types: resonant and non-resonant states in smooth flow, and in gradient flow. The characteristics of the three types of wind pressure fields are shown, respectively, in the symmetric and anti-symmetric modes.

Utilizing Kriging Metamodeling to Provide Practical and Effective Bridge Weigh-in-Motion

Emerging technologies are a strategic ally in the efficient management and preservation of pavements and bridges. Toward this end, different methodologies, such as weigh-in-motion (WIM), have been developed for the detection of overweight vehicles and traffic monitoring. Bridge weigh-in-motion (BWIM) systems can be installed and serviced without interrupting traffic flow. This paper presents a new approach for processing traditional strain response data. This proposal extends the BWIM concept of influence area from response time-histories. The dimensionality of the strain response waves is reduced by the calculation of the centroid and the area under the curve. Subsequently, these two dimensions are used as inputs to an ordinary Kriging (OK) metamodel to predict the gross vehicle weight (GVW) of the passing traffic. The OK methodology allows for the strategic selection of vehicles to train the BWIM metamodel. An example of the application of Kriging metamodeling (KM) to BWIM through the instrumentation of an in-service highway bridge located in Costa Rica is presented. Experimental horizontal strain data along with corresponding weight measurements from a static permanent weigh station were available for 90 trucks to validate the proposed enhanced BWIM methodology.

Upgrading framed structure seismic performance using steel Lever-Armed dampers in the Braces

This study evaluated the performance of frames equipped with novel lever-armed dampers in the braces (LAD-Brace). Cyclic loading tests and time-history response simulations using various earthquake ground motions were conducted on framed structures with and without LAD-Braces. The experimental results confirmed that the LAD-Braces effectively enhanced the strength of the structures. Significant achievements in elastic and inelastic stiffness of LAD-Braced frames over the SMRF justified the adequacy of the proposed design in deformation control and stability assurance. Simultaneous yielding on entire energy dissipation plate length incurred effective energy dissipation mechanism and efficient damping characteristics of the LAD-braced frames. LAD-Brace structural applicability was further evaluated by multi-bay-multi-story framed structural simulations using 11 different earthquake excitations. The simulation included the comparison of LAD-Braced frames to SMRFs and CBFs structure. The time-history structural responses revealed that the maximum story drifts and residual drifts of LAD-Braced frames were significantly reduced when compared with the corresponding SMRFs. In contrast to CBFs, analytical results showed that the LAD-Braced frame base shears were maintained at magnitudes equal to or less than the values of the corresponding SMRFs. This phenomenon combined with the effective reductions in story drifts and residual drifts validated the applicability of LAD-Brace in framed structural performance upgrading.

Safety Monitor Symmetry Concerning Beam Bridge Damage Utilizing the Instantaneous Amplitude Square Method

It is critical for the safety monitoring of highway bridges that beam bridge damage can be identified from the dynamic response of passing vehicles. Numerical simulations of passing vehicles were conducted utilizing the vehicle–bridge coupling vibration theory and the indirect measurement method. Fast Fourier transform was performed on the time history response of vehicle acceleration, and the driving frequency component response and its instantaneous amplitude square value (IAS value) were obtained by band-pass filtering and Hilbert transform processing. The identified IAS value detected the damage location of the bridge. The identification method of IAS value is used to analyze the applicability of a simply supported beam bridge, a continuous beam bridge, and an irregular skew beam bridge. The effects of vehicle speed, vehicle damping, bridge damping, and a social vehicle on damage identification are discussed. The results show that the effect of damage location is better when the vehicle speed is less than 4 m/s. In the presence of social vehicles, the excitation on the bridge increases, and the damage location can still be accurately determined by the IAS method. Vehicle damping and bridge damping have little effect on the results of damage identification. In structural health monitoring for bridges, this paper can provide a theoretical reference for the application of IAS motion sensing to identify the damage location indirectly.

Model updating and damage detection of jacket type platform using explicit and exact time domain sensitivity equation

In this paper, a new sensitivity equation is formulated for structural parameter estimation based on the time-history response. There are three methods for calculating the structural response variation with respect to changes in structural parameters in the time domain: Finite Difference Method (FDM), Direct Differentiation Method (DDM), and Adjoint variable Method (AVM). These methods are gradient-based, and they cannot compute the actual sensitivity. The proposed sensitivity equation explicitly calculates the sensitivity (closed-form sensitivity) in an exact manner and provides a linear relationship between the time history response and the variation of structural parameters. The efficiency and accuracy of the proposed method are examined for the finite element model updating of a jacket-type platform. Moreover, the effectiveness of the proposed method is evaluated in the presence of measurement and environmental errors. The performance of the proposed sensitivity equation is compared with the mentioned direct differentiation method.

Forced Vibration Analysis of Bimodular Microbeams Based on the Modified Couple Stress Theory

The forced vibration model of bimodular microbeams is studied in this paper based on the modified couple stress theory. The effects of the bimodular characteristic and the size effect are considered in this model. The forced vibration governing equation, boundary conditions, and initial conditions are obtained by Hamilton’s principle. The influence of the bimodular ratio and the material length scale parameters on the time history response are investigated based on the analytical method. Results show that the larger the two parameters, the higher the frequency and the smaller amplitude.

Safety action over oscillations of a beam excited by moving load via a new active vibration controller.

This paper presents a mixed active controller (NNPDCVF) that combines cubic velocity feedback with a negative nonlinear proportional derivative to reduce the nonlinear vibrating behavior of a nonlinear dynamic beam system. Multiple time-scales method treatment is produced to get the mathematical solution of the equations for the dynamical modeling with NNPDCVF controller. This research focuses on two resonance cases which are the primary and 1/2 subharmonic resonances. Time histories of the primary system and the controller are shown to demonstrate the reaction with and without control. The time-history response, as well as the impacts of the parameters on the system and controller, are simulated numerically using the MATLAB program. Routh-Hurwitz criterion is used to examine the stability of the system under primary resonance. A numerical simulation, using the MATLAB program software, is obtained to show the time-history response, the effect of the parameters on the system and the controller. An investigation is done into how different significant effective coefficients affect the resonance's steady-state response. The results demonstrate that the main resonance response is occasionally impacted by the new active feedback control's ability to effectively attenuate amplitude. Choosing an appropriate control Gaining quantity can enhance the effectiveness of vibration control by avoiding the primary resonance zone and unstable multi-solutions. Optimum control parameter values are calculated. Validation curves are provided to show how closely the perturbation and numerical solutions are related.

FORM-FINDING ANALYSIS FOR CABLE-REINFORCED MEMBRANE STRUCTURE BASED ON MINIMAL SURFACE

This paper applies a discretization formulation of the finite element method using the minimal surface for membrane structures and denotes an initial shape analysis procedure for a cable-reinforced HP-type suspension membrane structure and a cable-reinforced pneumatic membrane structure as numerical analysis model. In the computation process of cable introduction, moving boundaries are set and the cable is introduced step by step to denote a stable numerical computation procedure. In addition, finite elements of the initial shape obtained assuming a time history response analysis by wind are subdivided to compute the minimal surface again. To verify the equally tension property of the initial shape obtained based on minimal surface, a stress deformation analysis using the finite element method with the coordinate assumption is performed. For the pneumatic membrane structure, an example of stress deformation analysis due to an increase in internal pressure assuming strong winds is shown. The above clarifies the validity of this numerical procedure.

Reliability‐based robust design optimization for building‐connecting inertial mass damper

AbstractThis paper proposes an accurate and efficient reliability evaluation method for robust design optimization using a probabilistic approach. First, the validity of this method is verified using two benchmark functions. This method is then applied to the robust design optimization problem of building‐connecting damper parameters, and the effect of robust design is verified. The variation in the natural period and structural damping ratio of buildings is considered, and the criteria satisfaction rate (CSR) are directly evaluated using the response value calculated by time history response analysis.

THE EFFECT OF STIFFNESS AND STRENGTH OF COLUMN BASES IN FIRST STORY ON DAMAGE DISTRIBUTION OF WEAK-BEAM TYPE RIGID STEEL FRAMES

Exposed-type column bases are classified by two yield types, i.e., anchor-bolt type, and base-plate type. Restoring force characteristics are slip-type and maximum point orientation type respectively. The characteristics of damage distribution in steel frames with exposed-type column bases have been clarified by many past studies. However, the literature concerning quantitative evaluation and prediction formulas is limited. The prediction formulas are needed to design such structures avoiding damage concentration as much as possible. In this paper, the damage to column bases, the upper beam of the first story, and inside the first story in steel frames with column bases that have elastic perfectly plastic restoring force characteristics are evaluated quantitatively based on the comparison with "Basic Frame". After that, the proposed prediction formula is contrasted with the time-history response analyses.

Probabilistic seismic fragility assessment of vertical storage tank with a floating roof

Vertical storage tank is an important facility of oil depot, which may cause catastrophic accidents during strong earthquake, resulting in serious economic and environment consequences. The manuscript studies the seismic fragility of tank with a floating roof. A refined finite element model of the tank with three height-to-diameter ratios is developed. Time-history responses of sloshing wave height, base shear force and base bending moment of tank with and without a floating roof are analyzed. Then, time-history analysis of 55 ground motions is performed to establish seismic demand models for various responses and the most proper intensity measure is determined based on the dispersion and determination coefficient. Appropriate component-level and system-level damage states are defined by identifying possible failure modes during strong earthquake. Seismic fragility curves for different responses are derived for four damage states by cloud analysis. The results indicate that combined spectral acceleration is the most effective and sufficient IM and using only one component fragility to evaluate seismic performance may underestimate the tank system fragility. The results can provide practical advice for seismic risk assessment of individual tank or entire tank farm.

Dynamic analysis of beams vibrating on nonlinear poroelastic multi‐layered continuum

AbstractThe paper presents a framework for analysis of beams interacting with nonlinear‐poroelastic, layered continuums (e.g., clayey soils) when subjected to time‐dependent loads. The poroelastic layered continuum is characterized by a nonlinear‐elastic constitutive relationship that relates the secant shear modulus to the induced shear strain. The Biot's theory of consolidation is combined with a dynamic beam‐continuum interaction model to develop the analysis. The vertical consolidation settlement of the beam and the excess pore pressure in the porous continuum are assumed to be products of separable functions, and the extended Hamilton's principle of least action is applied to obtain the differential equations governing the inertial consolidation motion of the beam‐continuum system and the dissipation of excess pore pressure. An iterative numerical algorithm is used to solve these coupled differential equations following one‐dimensional finite element analysis in which the implicit Wilson‐Θ time integration scheme is used to obtain the time history of beam and continuum responses. The novelty of the framework is that it rigorously takes into account the nonlinear poroelastic soil‐structure interaction within a dynamic time‐integration framework with minimal computational resources. The characteristics of this newly developed model are illustrated through examples.

Size-dependent nonlinear vibration and instability of a damped microplate subjected to in-plane parametric excitation

The semi-analytical framework for nonlinear vibration and dynamic instability of a damped microplate under periodic parametric excitation is presented. The microplate is modeled using the higher-order shear deformation theory (HSDT) in conjugation with the modified strain gradient theory (MSGT). The governing partial differential equations of motion are obtained using Hamilton’s principle and further solved using Galerkin’s method. The ordinary differential equations without the nonlinear terms are solved using Bolotin’s method to obtain the dynamic instability region. A combination of the incremental harmonic balance (IHB) and the arc-length continuation methods is used to obtain the nonlinear forced vibration response. The effect of initial displacements on the steady-state response of the microplate is discussed. The Newmark-β method is used to obtain the time-history response plots. A comparison of results with those obtained from modified couple stress theory (MCST) and classical continuum theory (CCT) are examined. The effect of various parameters, such as the size of a plate, damping coefficient, static and dynamic loading factors, different boundary conditions, and different loading profiles, on the width of linear and nonlinear instability regions, are also studied.