• Title, Summary, Keyword: acceleration response

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Study on Improvement of Response Spectrum Analysis of Pile-supported Structure: Focusing on the Natural Periods and Input Ground Acceleration (잔교식 구조물의 응답스펙트럼 해석법 개선사항 도출 연구: 고유주기 및 입력지반가속도를 중점으로)

  • Yun, Jung-Won;Han, Jin-Tae;Kim, Jong-Kwan
    • Journal of the Korean Geotechnical Society
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    • v.36 no.6
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    • pp.17-34
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    • 2020
  • In response spectrum analysis of pile-supported structure, an amplified seismic wave should be used as the input ground acceleration through the site-response analysis. However, each design standard uses different input ground acceleration criteria, which leads to confusion in determining the appropriate input ground acceleration. In this study, the ground accelerations were calculated through dynamic centrifuge model test, and the response spectrum analysis was performed using the calculated ground acceleration. Then, the moments derived from the test and analysis were compared, and a method for determining the appropriate input ground acceleration in response spectrum analysis was presented. Comparison of the experimental and simulated results reveals that modeling of the ground using elastic springs allows proper simulation of the natural period of the structure, and the use of a seismic wave that is amplified at the ground surface as the input ground acceleration provided the most accurate results for the response analysis of pile-supported structures in sands.

Criteria for processing response-spectrum-compatible seismic accelerations simulated via spectral representation

  • Zerva, A.;Morikawa, H.;Sawada, S.
    • Earthquakes and Structures
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    • v.3 no.3_4
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    • pp.341-363
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    • 2012
  • The spectral representation method is a quick and versatile tool for the generation of spatially variable, response-spectrum-compatible simulations to be used in the nonlinear seismic response evaluation of extended structures, such as bridges. However, just as recorded data, these simulated accelerations require processing, but, unlike recorded data, the reasons for their processing are purely numerical. Hence, the criteria for the processing of acceleration simulations need to be tied to the effect of processing on the structural response. This paper presents a framework for processing acceleration simulations that is based on seismological approaches for processing recorded data, but establishes the corner frequency of the high-pass filter by minimizing the effect of processing on the response of the structural system, for the response evaluation of which the ground motions were generated. The proposed two-step criterion selects the filter corner frequency by considering both the dynamic and the pseudo-static response of the systems. First, it ensures that the linear/nonlinear dynamic structural response induced by the processed simulations captures the characteristics of the system's dynamic response caused by the unprocessed simulations, the frequency content of which is fully compatible with the target response spectrum. Second, it examines the adequacy of the selected estimate for the filter corner frequency by evaluating the pseudo-static response of the system subjected to spatially variable excitations. It is noted that the first step of this two-fold criterion suffices for the establishment of the corner frequency for the processing of acceleration time series generated at a single ground-surface location to be used in the seismic response evaluation of, e.g. a building structure. Furthermore, the concept also applies for the processing of acceleration time series generated by means of any approach that does not provide physical considerations for the selection of the corner frequency of the high-pass filter.

Effect on Transient Performance of Driver's Acceleration Type in MPI Gasoline Engine (운전자의 가속타입이 MPI 가솔린엔진의 과도성능에 미치는 영향)

  • 곽지현;전충환;장영준
    • Journal of the Korean Society of Marine Engineering
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    • v.24 no.1
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    • pp.75-81
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    • 2000
  • To provide the appropriate direction for development of transient control in a gasoline engine, transient performance analysis and evalution under four accelerating types based on typical driver's acceleration type were implemented by experimental study. In order to evaluate the characteristics of transient performance quanititatively, the concept and method by transient response specifications were introduced. Several performance parameters in terms of engine speed(RPM), manifold absolute pressure(MAP), fuel injection duration($\DeltatI_{nj}$) and air excess ratio($\lambda$) were emasured simultaneously during the four types of the throttle valve opening with the step motor controlled by PC. The result showed that transient response specifications in terms of delay time, rising time and settling time characterized the transient performance for four acceleration types quantitatively. Intensified acceleration type was most economical and linear acceleration type revealed the best emission performance.

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Firing Shock Measurement and Shock Response Spectrum Analysis of Small Arms (소구경 화기의 사격충격 측정 및 충격응답스펙트럼 분석)

  • Lee, Joon-Ho;Choe, Eui-Jung;Yoon, Joo-Hong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.588-593
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    • 2012
  • Nowadays, various forms of electro-optical rifle scope have been developed and used in order to enhance the accuracy of small arms. However, firing shock acceleration has characteristics of pyroshock having a big acceleration value with very short duration time, which the electro-optical scopes should be designed to sustain. In this paper, the firing shock acceleration, which is transmitted to the electro-optical scope, was measured and SRS (Shock Response Spectrum) analysis was performed by using the measured firing shock acceleration. Furthermore, a shock test condition using a drop-table shock tester, which can simulate the actual firing shock acceleration, was devised. The devised shock test condition will be utilized to test the electro-optical scope itself before attaching it to the small arms.

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Integrated Engine-CVT Control Considering Powertrain Response Lag in Acceleration

  • Kim, Tal-Chol;Kim, Hyun-Soo
    • Journal of Mechanical Science and Technology
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    • v.14 no.7
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    • pp.764-772
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    • 2000
  • In this paper, an engine-CVT integrated control algorithm is suggested by considering the inertia torque and the CVT ratio change response lag in acceleration. In order to compensate for drive torque time delay due to CVT response lag, two algorithms are presented: (1) an optimal engine torque compensation algorithm, and (2) an optimal engine speed compensation algorithm. Simulation results show that the optimal engine speed compensation algorithm gives better engine operation around the optimal operation point compared to the optimal torque compensation while showing nearly the same acceleration response. The performance of the proposed engine-CVT integrated control algorithms are compared with those of conventional CVT control, and It is found that optimal engine operation can be achieved by using integrated control during acceleration, and improved fuel economy can be expected while also satisfying the driver's demands.

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Elastic floor response spectra of nonlinear frame structures subjected to forward-directivity pulses of near-fault records

  • Kanee, Ali Reza Taghavee;Kani, Iradj Mahmood Zadeh;Noorzad, Assadollah
    • Earthquakes and Structures
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    • v.5 no.1
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    • pp.49-65
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    • 2013
  • This article presents the statistical characteristics of elastic floor acceleration spectra that represent the peak response demand of non-structural components attached to a nonlinear supporting frame. For this purpose, a set of stiff and flexible general moment resisting frames with periods of 0.3-3.6 sec. are analyzed using forty-nine near-field strong ground motion records. Peak accelerations are derived for each single degree of freedom non-structural component, supported by the above mentioned frames, through a direct-integration time-history analysis. These accelerations are obtained by Floor Acceleration Response Spectrum (FARS) method. They are statistically analyzed in the next step to achieve a better understanding of their height-wise distributions. The factors that affect FARS values are found in the relevant state of the art. Here, they are summarized to evaluate the amplification and/or reduction of FARS values especially when the supporting structures undergo inelastic behavior. The properties of FARS values are studied in three regions: long-period, fundamental-period and short-period. Maximum elastic acceleration response of non-structural component, mounted on inelastic frames, depends on the following factors: inelasticity intensity and modal periods of supporting structure; natural period, damping ratio and location of non-structural component. The FARS values, corresponded to the modal periods of supporting structure, are strongly reduced beyond elastic domain. However, they could be amplified in the transferring period domain between the mentioned modal periods. In the next step, the amplification and/or reduction of FARS values, caused by inelastic behavior of supporting structure, are calculated. A parameter called the response acceleration reduction factor ($R_{acc}$), has been previously used for far-field earthquakes. The feasibility of extending this parameter for near-field motions is focused here, suggested repeatedly in the relevant sources. The nonlinearity of supporting structure is included in ($R_{acc}$) for better estimation of maximum non-structural component absolute acceleration demand, which is ordinarily neglected in the seismic design provisions.

Study on Structural Safety of Car Securing Equipment for Coastal Carferry: Part I Estimation of Hull Acceleration using Direct Load Approach (국내 연안 카페리 차량 고박 장치 안전성에 관한 연구: 제I부 직접하중계산법을 이용한 선체 운동 가속도 산정)

  • Choung, Joonmo;Jo, Huisang;Lee, Kyunghoon;Lee, Young Woo
    • Journal of Ocean Engineering and Technology
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    • v.30 no.6
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    • pp.440-450
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    • 2016
  • The capsizing and consequent sinking of a coastal car ferry was recently reported, with numerous human casualties. The primary cause was determined to be a sudden turn with improperly stowed and secured cargo. Part I of this study introduces how long term acceleration components are determined from seakeeping analyses. A carferry with a displacement of 1,633 tonf was selected as the target vessel. Sea data that included the significant wave heights and periods were collected at four observation buoys, some of which were far away from two main voyage routes: Incheon-Jeju and Pusan-Jeju. Frequency response analyses were performed to obtain the linearized radiation force coefficients, hydrostatic stiffnesses, and wave excitation forces. Time response analyses were sequentially performed to produce the motion-induced acceleration processes. The probabilistic distributions of the acceleration components were determined using a peak and valley counting method. Long term extreme acceleration components were proposed as a final result.

Aeroelastic model test of a 610 m-high TV tower with complex shape and structure

  • Ding, Quanshun;Zhu, Ledong
    • Wind and Structures
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    • v.25 no.4
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    • pp.361-379
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    • 2017
  • In view of the importance of the wind-structure interaction for tall and slender structures, an aeroelastic model test of the 610m-high TV tower with a complex and unique structural configuration and appearance carried out successfully. The assembled aeroelastic model of the TV tower with complex shape and structure was designed and made to ensure the similarities of the major natural frequencies and the corresponding mode shapes. The simulation of the atmospheric boundary layer with higher turbulent intensity is presented. Since the displacement and acceleration responses at several measurement sections were directly measured in the wind tunnel test, a multi-mode approach was presented to indirectly estimate the displacement and acceleration responses at arbitrary structural floors based on the measured ones. It can be seen that it is remarkable for the displacement and acceleration responses of the TV tower in the two horizontal directions under wind loads and is small for the dynamic response of the torsional displacement and acceleration.

Estimation of amplification of slope via 1-D site response analysis (1차원 지반응답해석을 통한 사면의 증폭특성 규명)

  • Yun, Se-Ung;Park, Du-Hee
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.620-625
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    • 2009
  • The seismic slope stability is most often evaluated by the pseudo-static limit analysis, in which the earthquake loading is simplified as static inertial loads acting in horizontal and/or vertical directions. The transient loading is represented by constant acceleration via the pseudostatic coefficients. The result of a pseudostatic analysis is governed by the selection of the value of the pseudostatic coefficient. However, selection of the value is very difficult and often done in an ad hoc manner without a sound physical reasoning. In addition, the maximum acceleration is commonly estimated from the design guideline, which cannot accurately estimate the dynamic response of a slope. There is a need to perform a 2D dynamic analysis to properly define the dynamic response characteristics. This paper develops the modified one-dimensional seismic site response analysis. The modified site response analysis adjusts the density of the layers to simulate the change in mass and weight of the layers of the slope with depth. Multiple analyses are performed at various locations within the slope to estimate the change in seismic response of the slope. The calculated peak acceleration profiles with depth from the developed procedure are compared to those by the two-dimensional analyses. Comparisons show that the two methods result in remarkable match.

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CVT Ratio Control for Improvement of Fuel Economy by Considering Powertrain Response Lag

  • Lee, Heera;Kim, Hyunsoo
    • Journal of Mechanical Science and Technology
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    • v.17 no.11
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    • pp.1725-1731
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    • 2003
  • A high level CVT ratio control algorithm is proposed to improve the engine performance by considering the powertrain response lag. In this algorithm, the desired CVT speed ratio is modified from the vehicle velocity, which is estimated after the time delay due to the powertrain response lag. In addition, the acceleration map is constructed to estimate the vehicle acceleration from the throttle pedal position and the CVT ratio. Using the CVT ratio control algorithm and the acceleration map, vehicle performance simulations are performed to evaluate the engine performance and fuel economy. It is found that the fuel economy can be improved about 3.6% for FUDS by the ratio control algorithm for the target vehicle. In selecting the appropriate time delay, compromise between the fuel economy and the acceleration performance is required.