Support Excitation Research Articles

Experimental Seismic Performance of a Hybrid Sliding–Rocking Bridge for Various Specimen Configurations and Seismic Loading Conditions

AbstractThis paper presents the major findings of a shake table testing program on a large-scale (1:2.39) novel segmental concrete single-span bridge specimen. Emphasis is given on various specimen configurations and seismic loading conditions. The bridge specimen, termed hybrid sliding–rocking bridge, incorporated a box-girder superstructure with rocking joints and internal unbonded posttensioning (PT), and two single-column piers with internal unbonded PT. The pier columns included end rocking joints and intermediate sliding joints along the column height. Various configurations of the bridge specimen were considered with respect to the seismic mass and the superstructure-to-substructure connectivity. These configurations were subjected to far-field (F-F) and near-fault (N-F) ground motion ensembles scaled to various seismic hazard intensities. Asynchronous support excitation was also considered. The testing program included approximately 145 seismic tests. The dynamic response of the specimen was found...

Novel Design, Analytical and Experimental Studies of Spring Comprised Piezo Electric Energy Harvester

In this paper investigated a design of Spring-comprised Piezoelectric Energy Generator (SPEG) for random vibration, modelled and analyzed. The work basically focuses a novel spring comprised piezoelectric energy harvester with hitting masses, which is capable of harvesting energy from the ambient vibration. By properly designing the parameters, such as the length, diameter and mass of the shell and hitting masses, we can increase energy generated. For finding these parameters we carried out parametric analysis in SIMULINK. The main aim of the research is to get maximum voltage & power output. Analysis is carried out by varying the stiffness of spring and support excitation. Based on the analysis design of SPEG have been done and conducted experiments on the vibration shaker with a resonance frequency of 50Hz at support displacement is 50mm and developed a voltage of 18 volts as a output.

다중지점 지진하중을 받는 돔 구조물의 지진응답 제어

Spatial structures as like dome structure have the different dynamic characteristics from general rahmen structures. Therefore, it is necessary to accurately analyze dynamic characteristics and effectively control of seismic response of spatial structure subjected to multi-supported excitation. In this study, star dome structure that is subjected to multi-supported excitation was used as an example spatial structure. The response of the star dome structure under multiple support excitation are analyzed by means of the pseudo excitation method. Pseudo excitation method shows that the structural response is divided into two parts, ground displacement and structural dynamic response due to ground motion excitation. And the application of passive tuned mass damper(TMD) to seismic response control of star dome structures has been investigated. From this numerical analysis, it is shown that the seismic response of spatial structure under multiple support seismic excitation are different from those of spatial structure under unique excitation. And it is reasonable to install TMD to the dominant points of each mode. And it is found that the passive TMD could effectively reduce the seismic responses of dome structure subjected to multi-supported excitation.

Virtual Realization of Shaking Table Test of Structure in Sine-Swept Vibration by Multi-Support Excitation

In order to establish the virtual design method of shaking table test of structure in sine-swept vibration, the accurate sine-swept function in logarithmic variety is proposed by theoretic derivation. According to the numerical simulation, the dynamic response of structure in sine-swept vibration by multi-support excitation is acquired. And the maximum amplitude is less than that of structure in sine-swept vibration by single-support excitation based on the comparison with each other. However, several orders vibration mode are excited by the sine-swept vibration in multi-support excitation, and the structure resonates many times, which will increase the damage probability of structure. In other words, the load case of sine-swept vibration by multi-support excitation is worse than the case of sine-swept vibration by single support excitation. The conclusions above can provide basis for design and dynamic time-domain analysis of aerospace products of shaking table test in sine-swept excitation.

Potential Application in Energy Harvesting of Intermodal Energy Exchange in a Frame: FEM Analysis

This paper presents a Finite Element Analysis (FEA) of modal energy exchange and harvesting in a simple portal frame structure. We consider both horizontal and vertical support excitations resonant first with the first mode (sway mode) and latter with the second mode (the first symmetrical mode). As 2:1 internal resonance is present between these two modes, the phenomena of mode saturation and energy exchange (modal coupling) may occur. Thus, energy pumped into the system through one of the modes, is partially transferred to the other mode, not directly excited. An evaluation of the energy available for harvesting in each of the considered mode is computed.

Analytical study on the dynamic response of a beam with axial force subjected to generalized support excitations

Analytical solutions for the vibration of a beam with axial force subjected to generalized support motion are obtained in this paper. The finite element method (FEM) is introduced to validate the analytical solution obtained by an analytical approach. The dynamic responses of clamped–clamped, pinned–pinned and clamped–pinned beams with axial tension or compression are obtained via analytical approach and FEM. Comparing results show that the analytical approach is effective. The analytical analysis shows that the resonance will occur in general when the oscillatory frequency of transverse motion or rotation of any support end is equal to the natural frequency of the beam. Moreover, several cases in which the resonance disappears even if the frequencies of support excitations are equal to the natural frequencies of the beam are detected and are validated by the FEM solution.

Seismic response of nonstructural components attached on multistorey buildings

SUMMARYThe maintenance of integrity and functionality of nonstructural components during earthquake excitations is of paramount importance since mechanical failure of those systems can have dramatic consequences in terms of property damage and life safety of the buildings' occupants. This paper explores the dynamic response of nonstructural elements attached on multistory buildings with well‐established floor diaphragm action. Depending on the type of support conditions, seismic response of nonstructural components may be controlled either by acceleration or displacement: Nonstructural components that are subjected to uniform support excitation are controlled primarily by the absolute spectral acceleration developing at their point of attachment on the supporting building. On the contrary, seismic response of multiply supported nonstructural components depends primarily on the relative displacements between successive support points that are imposed by the supporting building during lateral sway. These findings are illustrated from the analytical formulation and its solution through time history analysis of the governing dynamic equation of motion of the primary and secondary components of a system modeled using finite elements. The model encompasses the assembly of a multistory building along with a multiply supported gas pipeline network. It is shown that the dependence of the seismic response of nonstructural components may be linked to the deformed shape of the supporting building at the state of its maximum lateral roof displacement, thereby enabling the definition of design procedures for these systems. Copyright © 2014 John Wiley & Sons, Ltd.

A weak energy–momentum method for stochastic instability induced by dissipation and random excitations

This paper focuses on the problem of stochastic instability resulting from the action of dissipation and random excitations. The energy–momentum theorem is extended from deterministic Hamiltonian systems to stochastic Hamiltonian systems, and then a weak energy–momentum method is presented for stochastic instability analysis of random systems suffering destabilizing effects of dissipation and random excitations. The presented method combines the stochastic averaging procedure to formulate the equivalent systems of random systems for obtaining the stochastic instability criteria in probability, and can be applied to a class of systems including random gyroscopic systems with positive or negative definite potential energy. As an example, the stochastic instability conditions of a Lagrange top subjected to random vertical support excitations are formulated to express the stochastic instability induced by dissipation and random excitations.

Drop Test and Finite Element Analysis of Test Board

Most electronic components have high precision and expensive features and people used the drop test to determine the reliability of these electronic components effectively. This study focused on the drop test of FR-4 test board according to the JEDEC standard, to understand the test board's basic mechanical properties and variations of stress and strain on test board. This study used finite element analysis software ANSYS/LS-DYNA to perform a drop test simulation of test board under JESD22-B111 standard, with 0.5ms pulse duration time and 1500G peak acceleration as test conditions. The support excitation method was used to predict the test board response during impact. The results between full model and quarter model were compared to verify the accuracy and efficiency of finite element analysis.

다중지점 지진하중에 대한 아치구조물의 지진응답 분석

Spatial structures have the different dynamic characteristics from general rahmen structures. Therefore, it is necessary to accurately analyze dynamic characteristics and seismic response for seismic design of spatial structure. Keel arch structure is used as an example structure because it has primary characteristics of spatial structures. In case of spatial structures with different ground condition and time lag, multiple support excitation may be subjected to supports of a keel arch structure. In this study, the response of the keel arch structure under multiple support excitation and with time lag are analyzed by means of the pseudo excitation method. Pseudo excitation method shows that the structural response is divided into two parts, ground displacement and structural dynamic response due to ground motion excitation. It is known that the seismic responses of spatial structure under multiple support excitation are different from those of spatial structure under simple excitation. And the seismic response of spatial structure with time lag are different from those of spatial structure without time lag. Therefore, it has to be necessary to analyze the seismic response of spatial structure under multiple support excitation and time lag because the spatial structure supports may be different and very long span. It is shown that the seismic response of spatial structure under multiple support seismic excitation are different from those of spatial structure under unique excitation.

The identification of a dam's modal parameters under random support excitation based on the Hankel matrix joint approximate diagonalization technique

Modal analysis is an effective method for monitoring a dam's health. Modal parameters can be identified from the measured vibration response of a dam under ambient excitation, such as that from an earthquake. In this paper, we first use the state space model to analyze the vibration of a dam under ambient support excitation and conclude that the nature excitation technique (NExT) can be used to the measured absolute acceleration response of the dam under band-limited stochastic support excitation to obtain its impulse response. To overcome some of the limitations of the traditional modal identification method for a structure under ambient excitation, we propose a modal parameter identification method based on the Hankel matrix joint approximate diagonalization (HJAD) technique. In this method, the Hankel matrix is defined as the covariance matrix of a vector, which is composed of measured acceleration responses, and their time-lagged data. This modal parameter identification method can be regarded as an improvement to the traditional time domain method because it introduces the joint approximate diagonalization (JAD) technique into the original method. On the other hand, the method can be regarded as an improvement to the SOBI-based modal identification method because it uses the Hankel matrix instead of the covariance matrix of response to perform the JAD. Therefore, this method combines the advantages of the two existing modal identification methods and overcomes some of their limitations. Compared with the SOBI-based modal parameter identification method, the implementation of the method presented in this paper is very convenient because we need only to add time-lagged response data to the analysis. The numerical analysis results show that the proposed modal parameter identification method based on HJAD technology not only has the advantage of a traditional blind modal parameter identification algorithm, but can also overcome the limitation of not being able to estimate more active modes than the number of available sensors. According to the satisfactory performance of this method in the analysis of strong-motion earthquake observation data for a gravity dam, the modal parameter identification method proposed in this paper has the potential for application in water conservancy engineering.

Seismic Performance Analysis of Tower Lines System under Multiple Support Excitation

In order to determine the calculational model of long span transmission tower structure under the multiple support excitation, tower-lines system are adopted. Seismic Performance of long span transmission tower lines system under Multiple Support Excitation were studied by time history analysis method. The seismic response difference of two kinds of excitation is analyzed from Dynamic Characteristics and the number of dangerous bar. It will offer the theory data for the seismic design of the kind of structure. Through analysis, the seismic response difference of the two kinds excitation is correlative to the apparent velocity; Therefore long span transmission tower structure should be considered the effect of multiple support excitation, otherwise the conclusion will be inclined to conservative or risk. Key words: tower lines system; seismic response; time history analysis,multiple support excitation

Neural network-based generation of artificial spatially variable earthquakes ground motions

In this paper, learning capabilities of two types of Arterial Neural Networks, namely hierarchical neural networks and Generalized Regression Neural Network were used in a two-stage approach to develop a method for generating spatial varying accelerograms from acceleration response spectra and a distance parameter in which generated accelerogram is desired. Data collected from closely spaced arrays of seismographs in SMART-1 array were used to train neural networks. The generated accelerograms from the proposed method can be used for multiple support excitations analysis of structures that their supports undergo different motions during an earthquake.

상이한 지반조건을 갖는 아치구조물의 지진응답 분석

Spatial structures have the different dynamic characteristics from general rahmen structures. Therefore, it is necessary to accurately analyze dynamic characteristics and seismic response of spatial structure for seismic design of spatial structure. An arch structure is used as an example structure because it has primary characteristics of spatial structures. Multiple support excitation may be subjected to supports of a spatial structure because ground condition of spatial structures is different. In this study, the response analysis of the arch structure under multiple support excitation and simple support excitation is studied. By means of the pseudo excitation method, the seismic response is analyzed for long span spatial structure. It shows that the structural response is divided into two parts, ground displacement and structural dynamic response due to ground motion excitation. It is known that the seismic response of spatial structure under multiple support excitation and simple support excitation are the different in some case. Therefore, it has to be necessary to analyze the seismic response of spatial structure under multiple support excitation because the spatial structure supports may be different.

The Seismic Response Analysis of the Jacket under Multiple Support Excitation

The effect of incoherency of seismic waves and wave travel on the displacement and force response of jacket structure are investigated from the maximum force, reaction force, the displacement, and so on. The conclusions illustrate it is necessary to consider the effect of multiple support excitation. The research of the differences of seismic response under multiple support excitation from uniform excitation presents the theoretical foundation on aseismatic projects for long span space structures such as jacket.

Some Comments on the Nonlinear Dynamics of a Portal Frame under Base Excitation

This paper presents a nonlinear dynamic analysis of a flexible portal frame subjected to support excitation, which is provided by an electro-dynamical shaker. The main goal of this study is to investigate the dynamic interactions between a flexible portal frame and a nonlinear electrical support excitation. The numerical analysis shows a complex behavior of the system, which can be observed by phase spaces, Poincare sections and bifurcation diagrams.

Some Comments on the Nonlinear Dynamics of a Portal Frame under Base Excitation

This paper presents a nonlinear dynamic analysis of a flexible portal frame subjected to support excitation, which is provided by an electro-dynamical shaker. The main goal of this study is to investigate the dynamic interactions between a flexible portal frame and a nonlinear electrical support excitation. The numerical analysis shows a complex behavior of the system, which can be observed by phase spaces, Poincaré sections and bifurcation diagrams.

Seismic Response of Spatial Structure Subjected to Multi-Support Earthquake Load

장경간의 대공간구조물은 지진하중에 의하여 일반구조물과는 다른 응답특성이 나타나고 있으므로 대공간구조물에 대한 내진설계를 위해서는 대공간구조물의 동적특성 및 지진응답특성에 대한 정확한 분석이 필요하다. 본 논문에서는 예제 구조물로 대공간구조물의 동적특성을 기본적으로 내재하고 있는 장견간의 아치구조물로 선정하여 다중지점 지진하중이 가진되는 대공간구조물의 진동응답 특성을 분석하였다. 다중지점 지진하중은 대공간구조물의 지점 지반조건이 다른 경우 그리고 시간지연을 갖는 지진하중이 가진되는 경우로 하여 수치해석을 수행하였다. 다중지점 지진하중 적용한 경우의 지진응답이 단일 지진하중 적용에 의한 지진응답과 비교하여 경우에 따라서 상이한 지진응답을 나타내고 있다. 따라서 대공간구조물의 경우에 정확한 지진응답 분석 및 적절한 내진설계를 위해서는 다중지점 지진하중을 적용하여 지진응답을 분석하는 것 바람직하다. Spatial structures have the different dynamic characteristics from general rahmen structures. Therefore, it is necessary to accurately analyze dynamic characteristics and seismic response for seismic design of spatial structure. Keel arch structure is used as an example structure because it has primary characteristics of spatial structures. In case of spatial structures with different ground condition and time lag, multiple support excitation may be subjected to supports of a keel arch structure. In this study, the response of the keel arch structure under multiple support excitation and with time lag are analyzed by means of the pseudo excitation method. Pseudo excitation method shows that the structural response is divided into two parts, ground displacement and structural dynamic response due to ground motion excitation. It is known that the seismic responses of spatial structure under multiple support excitation are different from those of spatial structure under simple excitation. And the seismic response of spatial structure with time lag are different from those of spatial structure without time lag. Therefore, it has to be necessary to analyze the seismic response of spatial structure under multiple support excitation and time lag because the spatial structure supports may be different and very long span. It is shown that the seismic response of spatial structure under multiple support seismic excitation are different from those of spatial structure under unique excitation.

The Seismic Response Analysis Method of the Jacket under Multiple Support Excitation

With the development of demand of exploiting offshore oil reserves, the Jacket platform structure’ span and depth is more and more large, so the seismic analysis of the jacket structure will become more and more complicated. In the dynamic analysis of long-span structures, multiple support excitation may be accounted is necessary. For big jacket structure, it is more accurate and reasonable by multiple support excitation than by uniform excitation. The objective of the research described herein is to develop a simplified method to investigate the effect of multiple support excitation on the jacket structure.

On the response spectrum of Euler–Bernoulli beams with a moving mass and horizontal support excitation

In this study, the response spectrum of a time-varying system such as a beam subjected to moving masses under a harmonic and earthquake support excitations is explored. The excitations are supposed to act on the horizontal directions of the beam axis. The inertial effect of the moving masses on the natural frequencies of the beam for different cases of loading is investigated and a critical value of a so called parameter “mass staying time” is presented to avoid dynamic instability of the system. Finally, some 3D response spectra for different supports excitations as well as the beam natural frequencies are depicted.