• Title, Summary, Keyword: near-fault ground motion

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A Study on Characteristics and Dynamic Response Spectrum of Near Fault Ground Motions (근거리지진의 특성과 동적응답스펙트럼에 관한 연구)

  • Bang, Myung-Seok;Han, Sung-Ho
    • Journal of the Korean Society of Safety
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    • v.20 no.3
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    • pp.143-151
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    • 2005
  • In this study, it is demonstrated that how the effect of the Near Fault Ground Motion affects the response of the structure. Considering the general characteristic of Near Fault Ground Motion the characteristics of Near Fault Ground Motions is analysed by elastic response spectrums, and the inelastic response spectrum is evaluated with the ductility and the yield strength to consider the inelastic behavior which couldn't be simulated through the elastic response spectrum. The result of this study shows that the effect of Near Fault Ground Motion should be considered in the long period range of long span structures but the domestic seismic design code was developed based on Far Fault Ground Motions, so the effects of Near Fault Ground Motions, which is very serious especially in large structures with a long period, are not considered. Therefore, the effect of the Near Fault Ground Motion has to be examined especially in the seismic performance evaluation of long period structure.

Fragility analysis of concrete-filled steel tube arch bridge subjected to near-fault ground motion considering the wave passage effect

  • Liu, Zhen;Zhang, Zhe
    • Smart Structures and Systems
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    • v.19 no.4
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    • pp.415-429
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    • 2017
  • This paper focuses on the impact of the wave passage effect on the long-span bridge. In order to make the wave passage effect more obvious, ground motion samples are selected from the near-fault ground motion of the 1999 Chi-Chi earthquake and an arch bridge with a 280m main span is selected as a bridge sample. The motion ground samples are divided into two groups according to the characteristics of near-fault. A sequence of fragility curves is developed. It is shown that the seismic damage is increased by the wave passage effect and the increase is more obvious in the near-fault ground motion.

Near-fault ground motion effects on the nonlinear response of dam-reservoir-foundation systems

  • Bayraktar, Alemdar;Altunisik, Ahmet Can;Sevim, Baris;Kartal, Murat Emre;Turker, Temel
    • Structural Engineering and Mechanics
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    • v.28 no.4
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    • pp.411-442
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    • 2008
  • Ground motions in near source region of large crustal earthquakes are significantly affected by rupture directivity and tectonic fling. These effects are the strongest at longer periods and they can have a significant impact on Engineering Structures. In this paper, it is aimed to determine near-fault ground motion effects on the nonlinear response of dams including dam-reservoir-foundation interaction. Four different types of dam, which are gravity, arch, concrete faced rockfill and clay core rockfill dams, are selected to investigate the near-fault ground motion effects on dam responses. The behavior of reservoir is taken into account by using Lagrangian approach. Strong ground motion records of Duzce (1999), Northridge (1994) and Erzincan (1992) earthquakes are selected for the analyses. Displacements, maximum and minimum principal stresses are determined by using the finite element method. The displacements and principal stresses obtained from the four different dam types subjected to these nearfault strong-ground motions are compared with each other. It is seen from the results that near-fault ground motions have different impacts on the dam types.

Response of the structures excited by the near fault ground motion (Near Fault Ground Motion에 의한 구조물의 거동 특성 연구)

  • Kim, Jae-Kwan;Kim, Jung-Han
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.42-46
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    • 2005
  • Ground motions with the near fault effects are studied for the seismic design and the analysis of structures. The characteristics of the velocity pulse by the forward directivity are studied and the relations between velocity pulse and earthquake magnitude are investigated. The elastic response spectra of the near fault ground motion are compared with these of the far fault ground motion. And effects on the behaviors of structures are studied by the analysis of the elastic and the inelastic single degree of freedom system in terms of the response spectrum and the ductility demand.

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Characterization and modeling of near-fault pulse-like strong ground motion via damage-based critical excitation method

  • Moustafa, Abbas;Takewaki, Izuru
    • Structural Engineering and Mechanics
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    • v.34 no.6
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    • pp.755-778
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    • 2010
  • Near-fault ground motion with directivity or fling effects is significantly influenced by the rupture mechanism and substantially different from ordinary records. This class of ground motion has large amplitude and long period, exhibits unusual response spectra shapes, possesses high PGV/PGA and PGD/PGA ratios and is best characterized in the velocity and the displacement time-histories. Such ground motion is also characterized by its energy being contained in a single or very few pulses, thus capable of causing severe damage to the structures. This paper investigates the characteristics of near-fault pulse-like ground motions and their implications on the structural responses using new proposed measures, such as, the effective frequency range, the energy rate (in time and frequency domains) and the damage indices. The paper develops also simple mathematical expressions for modeling this class of ground motion and the associated structural responses, thus eliminating numerical integration of the equations of motion. An optimization technique is also developed by using energy concepts and damage indices for modeling this class of ground motion for inelastic structures at sites having limited earthquake data.

Probabilistic sensitivity analysis of suspension bridges to near-fault ground motion

  • Cavdar, Ozlem
    • Steel and Composite Structures
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    • v.15 no.1
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    • pp.15-39
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    • 2013
  • The sensitivities of a structural response due to variation of its design parameters are prerequisite in the majority of the algorithms used for fundamental problems in engineering as system uncertainties, identification and probabilistic assessments etc. The paper presents the concept of probabilistic sensitivity of suspension bridges with respect to near-fault ground motion. In near field earthquake ground motions, large amplitude spectral accelerations can occur at long periods where many suspension bridges have significant structural response modes. Two different types of suspension bridges, which are Bosporus and Humber bridges, are selected to investigate the near-fault ground motion effects on suspension bridges random response sensitivity analysis. The modulus of elasticity is selected as random design variable. Strong ground motion records of Kocaeli, Northridge and Erzincan earthquakes are selected for the analyses. The stochastic sensitivity displacements and internal forces are determined by using the stochastic sensitivity finite element method and Monte Carlo simulation method. The stochastic sensitivity displacements and responses obtained from the two different suspension bridges subjected to these near-fault strong-ground motions are compared with each other. It is seen from the results that near-fault ground motions have different impacts stochastic sensitivity responses of suspension bridges. The stochastic sensitivity information provides a deeper insight into the structural design and it can be used as a basis for decision-making.

Dynamic Response Characteristics of the Suspension Bridge Subjected to Near Fault Ground Motions (근거리 지진에 의한 현수교의 동적응답특성)

  • 한성호;이강혁;유병률;방명석;신재철
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.484-491
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    • 2004
  • In this study, the effect of the Near Fault Ground Motion which hasn't been considered at the domestic seismic design is demonstrated through the seismic response analysis of suspension bridge. After selecting the typical Near and Far Fault Ground Motion, the response characteristics are analysed by conducting the seismic response analysis about the long period suspension bridge which is expected to suffer the effect of Near Fault Ground Motions more largely. According to the results of this study, the Near Fault Ground Motions affect the suspension bridge more considerably than the Far Fault Ground Motions.

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On the improvement of inelastic displacement demands for near-fault ground motions considering various faulting mechanisms

  • Esfahanian, A.;Aghakouchak, A.A.
    • Earthquakes and Structures
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    • v.9 no.3
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    • pp.673-698
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    • 2015
  • This paper investigates inelastic seismic demands of the normal component of near-fault pulse-like ground motions, which differ considerably from those of far-fault ground motions and also parallel component of near-fault ones. The results are utilized to improve the nonlinear static procedure (NSP) called Displacement Coefficient Method (DCM). 96 near-fault and 20 far-fault ground motions and the responses of various single degree of freedom (SDOF) systems constitute the dataset. Nonlinear Dynamic Analysis (NDA) is utilized as the benchmark for comparison with nonlinear static analysis results. Considerable influences of different faulting mechanisms are observed on inelastic seismic demands. The demands are functions of the strength ratio and also the pulse period to structural period ratio. Simple mathematical expressions are developed to consider the effects of near-fault motion and fault type on nonlinear responses. Modifications are presented for the DCM by introducing a near-fault modification factor, $C_N$. In locations, where the fault type is known, the modifications proposed in this paper help to obtain a more precise estimate of seismic demands in structures.

Seismic Performance of Bridge with Pile Bent Structures in Soft Ground against Near-Fault Ground Motions (연약지반에 건설된 단일형 현장타설말뚝 교량의 근단층지반운동에 대한 내진성능)

  • Sun, Chang-Ho;An, Sung-Min;Kim, Jung-Han;Kim, Ick-Hyun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.7
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    • pp.137-144
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    • 2019
  • For the structures near the seismogenic fault, the evaluation of seismic performance against near-fault ground motions is important as well as for design ground motions. In this study, characteristics of seismic behaviors and seismic performance of the pile-bent bridge constructed on the thick soft soil site with various weak soil layers were analyzed. The input ground motions were synthesized by the directivity pulse parameters for intra-plate regions. The ground motion acceleration histories of each layer were obtained by one-dimensional site response analysis. Each soil layer was modeled by equivalent linear springs, and multi-support excitations with different input ground motions at each soil spring were applied for nonlinear seismic analyses. The analysis result by the near-fault ground motions and ground motions matched to design spectra were compared. In case of the near fault ground motion input, the bridge behaved within the elastic range but the location of the maximum moment occurred was different from the result of design ground motion input.

The Earthquake Response Characteristics and Seismic Safety Evaluation of Steel Cable Stayed Bridges (강사장교의 지진응답특성 및 내진 안전성 평가)

  • Han, Sung Ho;Shin, Jae Chul;Choi, Jin Woo
    • Journal of Korean Society of Steel Construction
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    • v.19 no.5
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    • pp.435-454
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    • 2007
  • In this study, we demonstrated the characteristics of the near-fault ground motion thatwas not considered in the domestic seismic design code and how the effect of the near-fault ground motion affects the response of cable-stayed bridges. Afterselecting the actual measurement records of the typical near- and far-fault ground motion, the characteristics of ground motion is analyzed using the elastic and inelastic response spectrum. Analyzing the response regarding the earthquake's characteristics on cable-stayed bridges by the typical three-type cable-stayed bridges and the actual cable-stayed bridge, the characteristics of responses about main members are compared and analyzed. Moreover,reliability analysis is accomplished using the results of the seismic response analysis, and the seismic safety of the cable-stayed bridges is evaluated quantitatively as a reliability index and probability of failure. According to the results of the response spectrum, the earthquake response analysis and the reliability analysis, because the effect of the near fault ground motion against the response of cable-stayed bridges is different from the effect of the existing far-fault ground motion, it should be considered as an important factor when designing cable-stayed bridges.