• 제목/요약/키워드: Structural response velocity

검색결과 219건 처리시간 0.027초

Quantitative impact response analysis of reinforced concrete beam using the Smoothed Particle Hydrodynamics (SPH) method

  • Mokhatar, S.N.;Sonoda, Y.;Kueh, A.B.H.;Jaini, Z.M.
    • Structural Engineering and Mechanics
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    • 제56권6호
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    • pp.917-938
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    • 2015
  • The nonlinear numerical analysis of the impact response of reinforced concrete/mortar beam incorporated with the updated Lagrangian method, namely the Smoothed Particle Hydrodynamics (SPH) is carried out in this study. The analysis includes the simulation of the effects of high mass low velocity impact load falling on beam structures. Three material models to describe the localized failure of structural elements are: (1) linear pressure-sensitive yield criteria (Drucker-Prager type) in the pre-peak regime for the concrete/mortar meanwhile, the shear strain energy criterion (Von Mises) is applied for the steel reinforcement (2) nonlinear hardening law by means of modified linear Drucker-Prager envelope by employing the plane cap surface to simulate the irreversible plastic behavior of concrete/mortar (3) implementation of linear and nonlinear softening in tension and compression regions, respectively, to express the complex behavior of concrete material during short time loading condition. Validation upon existing experimental test results is conducted, from which the impact behavior of concrete beams are best described using the SPH model adopting an average velocity and erosion algorithm, where instability in terms of numerical fragmentation is reduced considerably.

Wind power spectra for coastal area of East Jiangsu Province based on SHMS

  • Wang, Hao;Tao, Tianyou;Wu, Teng
    • Wind and Structures
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    • 제22권2호
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    • pp.235-252
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    • 2016
  • A wind velocity power spectrum (WVPS) with high fidelity is extremely important for accurate prediction of structural buffeting response. WVPS heavily depends on the geographical locations, local terrains and topographies. Hence, field measurement of wind characteristics may be the unique way to obtain the accurate WVPS for a specific region. In this paper, a systematic analysis and discussions of existing WVPSs were performed. Six recorded strong wind data from the structural health monitoring systems (SHMS) of Runyang Suspension Bridge (RSB) and Sutong Cable-stayed Bridge (SCB) in Jiangsu Province of China were selected for analysis. The measured and pre-processed wind velocity data was first transformed from time domain to frequency domain to obtain the measured spectrum. The spectrum for each strong wind was then fitted using the nonlinear least square method and compared with both the fitted spectrum from statistical analysis and the recommended spectrum in specifications. The modified Kaimal spectrum was proved to be the "best" choice for the coastal area of East Jiangsu Province. Finally, a suitable WVPS formula fit for the coastal area of East Jiangsu Province was presented based on the modified Kaimal spectrum. Results in this study provide a more accurate and reliable WVPS for wind-resistant design of engineering structures in the coastal area of East Jiangsu Province.

EQPS를 이용한 복합장갑의 해석 및 최적설계 (The analysis and optimization of dual armor plate considering EQPS)

  • 박명수;유정훈;정동택
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 2004년도 봄 학술발표회 논문집
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    • pp.111-118
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    • 2004
  • For the precise analysis of high velocity impact problem though FEM with element erosive method, the adequate mesh size and critical equivalent plastic strain(EQPS) is chosen prior to the simulation. In this research, it is strongly required from a standpoint that critical EQPS is used to decide whether perforation occurs or not. The optimization of dual armor plate consisting of 4340 steel and 2024 aluminium against a die steel sphere with high-velocity has been suggested using Lagrangian explicit time-integration code, NET2D. The response surface method based on the design of experiment is utilized for the size optimization. The optimized thickness of each layer, in which perforation does not occur, the strength of multi-layer is maximized and total weight is minimized, is obtained at a constant velocity of a pellet with a designated total thickness.

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재하차량 속도에 따른 PSC-I 거더 교량의 거동분석 (Response Analysis of PSC-I Girder Bridges for Vehicle's Velocity)

  • 박문호;김기욱
    • 한국구조물진단유지관리공학회 논문집
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    • 제12권3호
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    • pp.127-134
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    • 2008
  • 교량의 거동은 교량의 지간 및 노면조도, 주행차량의 중량, 주행속도등 여러 요인들에 의해 달라지므로 교량의 동적거동을 정확히 예측하여 반영하기는 매우 어렵다. 우리나라 표준 시방 기준은 이러한 동적효과를 충격계수로 정의하고, 활하중에 충격계수를 곱하여 설계하중을 증가시키는 방법으로 동적효과를 고려하고 있다. 그러나 각 나라별로 충격계수를 적용하는 방법이 다르고, 아직까지도 명확하게 규명하지 못하고 있다. 그러므로 본 연구에서는 현재 사용 중인 PSC-I 거더교에 대하여 주행차량에 의한 동적 특성을 규명하기 위하여 동적재하, 정적재하, 의사정적재하시험을 이용하였다. 현장 재하시험에서 얻어진 결과를 통해 재하 속도에 따른 변위와 Strain관계를 찾을 수 있었으며, 이를 바탕으로 현재 논란이 있는 국내의 충격계수에 관한 경험식에 대하여 보다 합리적이고 실제적인 거동이 포함되도록 일조하는데 본 연구의 목적이 있다.

Quantification of nonlinear seismic response of rectangular liquid tank

  • Nayak, Santosh Kumar;Biswal, Kishore Chandra
    • Structural Engineering and Mechanics
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    • 제47권5호
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    • pp.599-622
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    • 2013
  • Seismic response of two dimensional liquid tanks is numerically simulated using fully nonlinear velocity potential theory. Galerkin-weighted-residual based finite element method is used for solving the governing Laplace equation with fully nonlinear free surface boundary conditions and also for velocity recovery. Based on mixed Eulerian-Lagrangian (MEL) method, fourth order explicit Runge-Kutta scheme is used for time integration of free surface boundary conditions. A cubic-spline fitted regridding technique is used at every time step to eliminate possible numerical instabilities on account of Lagrangian node induced mesh distortion. An artificial surface damping term is used which mimics the viscosity induced damping and brings in numerical stability. Four earthquake motions have been suitably selected to study the effect of frequency content on the dynamic response of tank-liquid system. The nonlinear seismic response vis-a-vis linear response of rectangular liquid tank has been studied. The impulsive and convective components of hydrodynamic forces, e.g., base shear, overturning base moment and pressure distribution on tank-wall are quantified. It is observed that the convective response of tank-liquid system is very much sensitive to the frequency content of the ground motion. Such sensitivity is more pronounced in shallow tanks.

음향을 이용한 복합 적층판의 층간분리 예측 (Prediction of Delamination for Composite Laminates Using Sound Radiation)

  • 김성준;채동철
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2005년도 춘계학술대회논문집
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    • pp.800-804
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    • 2005
  • In this paper, the radiated sound pressure induced by low velocity impact is obtained by solving the Rayleigh integral equation. For structurally radiated noise, the sound field is directly coupled to the structural motion. Therefore the impact response should be analyzed. It is well known that the presence of the delamination in a composite laminate introduces a local flexibility which changes the dynamic characteristic of the structure. The 2-D simplified delamination model is used to analyze the impact response. And the 3-D non-linear finite element model is developed using gap element to avoid the overlap and penetration between the upper and lower sub-laminates at delamination region. Predicted impact response using 2-D equivalent delamination model are compared with the numerical ones from the 3-D non-linear finite element model.

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Numerical analysis of a long-span bridge response to tornado-like winds

  • Hao, Jianming;Wu, Teng
    • Wind and Structures
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    • 제31권5호
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    • pp.459-472
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    • 2020
  • This study focused on the non-synoptic, tornado-like wind-induced effects on flexible horizontal structures that are extremely sensitive to winds. More specifically, the nonuniform, intensive vertical wind-velocity and transient natures of tornado events and their effects on the global behavior of a long-span bridge were investigated. In addition to the static part in the modeling of tornado-like wind-induced loads, the motion-induced effects were modeled using the semi-empirical model with a two-dimensional (2-D) indicial response function. Both nonlinear wind-induced static analysis and linear aeroelastic analysis in the time domain were conducted based on a 3-D finite-element model to investigate the bridge performance under the most unfavorable tornado pattern considering wind-structure interactions. The results from the present study highlighted the important effects due to abovementioned tornado natures (i.e., nonuniform, intensive vertical wind-velocity and transient features) on the long-span bridge, and hence may facilitate more appropriate wind design of flexible horizontal structures in the tornado-prone areas.

Seismic response of nonstructural components considering the near-fault pulse-like ground motions

  • Zhai, Chang-Hai;Zheng, Zhi;Li, Shuang;Pan, Xiaolan;Xie, Li-Li
    • Earthquakes and Structures
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    • 제10권5호
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    • pp.1213-1232
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    • 2016
  • This paper investigates the response of nonstructural components in the presence of nonlinear behavior of the primary structure considering the near-fault pulse-like ground motions. A database of 81 near-fault pulse-like ground motions is used to examine the effect of these ground motions on the response of nonstructural components. For comparison, a database of 573 non-pulse-like ground motions selected from the PEER database is also employed. The effects of peak ground velocity (PGV), maximum incremental velocity (MIV), primary structural degrading behavior and damping of nonstructural components are evaluated and discussed statistically. Results are presented in terms of amplification factor which quantifies the effect of inelastic deformations of the primary structure on subsystem responses. The results indicate that the near-fault pulse-like ground motions can significantly increase the amplification factors of nonstructural components with primary structural period and the magnitude of increase can reach 17%. The effect of PGV and MIV on amplification factors tends to increase with the increase of primary structural ductility. The near-fault pulse-like ground motions are more dangerous to components supported by structures with strength and stiffness degrading behavior than ordinary ground motions. A new simplified formulation is proposed for the application of amplification factors for design of nonstructural components for near-fault pulse-like ground motions.

A study on determination of target displacement of RC frames using PSV spectrum and energy-balance concept

  • Ucar, Taner;Merter, Onur;Duzgun, Mustafa
    • Structural Engineering and Mechanics
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    • 제41권6호
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    • pp.759-773
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    • 2012
  • The objective of this paper is to present an energy-based method for calculating target displacement of RC structures. The method, which uses the Newmark-Hall pseudo-velocity spectrum, is called the "Pseudo-velocity Spectrum (PSVS) Method". The method is based on the energy balance concept that uses the equality of energy demand and energy capacity of the structure. First, nonlinear static analyses are performed for five, eight and ten-story RC frame structures and pushover curves are obtained. Then the pushover curves are converted to energy capacity diagrams. Seven strong ground motions that were recorded at different soil sites in Turkey are used to obtain the pseudo-acceleration and the pseudo-velocity response spectra. Later, the response spectra are idealised with the Newmark-Hall approximation. Afterwards, energy demands for the RC structures are calculated using the idealised pseudo-velocity spectrum. The displacements, obtained from the energy capacity diagrams that fit to the energy demand values of the RC structures, are accepted as the energy-based performance point of the structures. Consequently, the target displacement values determined from the PSVS Method are checked using the displacement-based successive approach in the Turkish Seismic Design Code. The results show that the target displacements of RC frame structures obtained from the PSVS Method are very close to the values calculated by the approach given in the Turkish Seismic Design Code.

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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    • 제3권3_4호
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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.