• Title/Summary/Keyword: eccentricities

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Surface displacements due to tunneling in granular soils in presence and absence of geosynthetic layer under footings

  • Rebello, Nalini E.;Shivashankar, R.;Sastry, Vedala R.
    • Geomechanics and Engineering
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    • v.15 no.2
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    • pp.739-744
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    • 2018
  • This paper presents the results of numerical modeling studies on the effect of displacements of tunneling in granular soils. Presence of building loads is considered, to find displacement generated at the surface on tunnel. Effect of varying eccentricities of building is simulated, to find influence of building on vertical and horizontal displacement. Studies were carried out in two cases of with and without a geosynthetic layer installed at the bottom of the footing. Results of analysis revealed, the presence of geosynthetic layer under footing, with building placed on centre line, reduced the surface displacements compared to displacement generated without geosynthetic layer. Presence of geosynthetic layer under footing had a dominant effect in reducing displacements in high storey structures. However, when the building was shifted to greater eccentricities from centre line, presence of geosynthetic layer, led to insignificant reduction of displacements on the centre line at the surface.

SEARCH FOR PHOTOMETRIC ABUNDANCE INDICES FOR M DWARF STARS

  • Lee, Sang-Gak
    • Journal of The Korean Astronomical Society
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    • v.15 no.2
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    • pp.49-58
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    • 1982
  • The UBVRIHKL magnitudes on Johnson system and space motions of M dwarf stars have been collected. This sample of M stars have been distinguished on a purely kinematical basis; the one with e<0.15, young disk population, with 0.150.3 halo population. On the color-color diagrams and the color excess-orbital eccentricity diagrams, there is no distinction between the old disk stars and the young disk stars. However (I-H) color could be used to distinguish halo stars from young and old disk stars and the color excesses, ${\Delta}(U-B),\;{\Delta}(B-V),\;{\Delta}(V-R),\;{\Delta}(H-K),\;{\Delta}(K-L),\;and\;{\Delta}(B-R)$ can be used as abundance indicators only for the halo stars. But these color excesses which are measures of blue excesses, are positive for the halo stars with smaller eccentricities and become negative for those with larger eccentricities.

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Nonlinear Stability Analysis of Slender Concrete Columns (세장한 콘크리트 기둥의 비선형 안정 해석)

  • 김진근;양주경;김원근
    • Proceedings of the Korea Concrete Institute Conference
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    • 1992.04a
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    • pp.80-85
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    • 1992
  • A nonlinear second-order analysis program that properly describes the nonlinear behavior of concrete was developed by using the layering technique. As the slenderness ratio of column is increased, the peaks of P-M curve lie remote from the section interaction diagram for the same eccentricities. But the peaks of P-M curve lie rather close to the section interaction diagram for very large eccentricities. In this study , the effects of compressive strength of concrete, longitudinal steel ratio, and yield strength of steel on second-order moment of concrete columns were analyzed. As the compressive strength of concrete and the yield strength of steel are increased, the ratio of peak axial force to maximum axial strength for concentrically loaded short column( Pu/Po) is decreased. But as the longitudinal steel ratio is increased, the ratio , Pu/Po increases.

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A Study on the Relationship between the Eccentricity and the Level of Damage in the Seismic Response of Buildings with Plan Irregularities (지진 하중을 받는 평면 비정형 건물의 편심과 손상도의 상관관계에 대한 연구)

  • Jeong, Seoung-Hoon;Lee, Kwang-Ho
    • Journal of the Earthquake Engineering Society of Korea
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    • v.14 no.3
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    • pp.49-57
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    • 2010
  • Most previous research on the seismic response of structures with plan irregularities have focused on the relationship between the eccentricity and the amount of torsion. This approach cannot provide the direct relationship between the irregularity and the damage. Therefore, an investigation on the relationship between the eccentricities of buildings with plan irregularities and the damage index was performed. Inelastic dynamic time-history analyses were performed on one-story buildings with various eccentricities. For the damage assessment, a 3D damage index was adopted to reflect the effect of the bi-directional response and torsion. Based on the analysis results, buildings with eccentricities of 10%, 20% and 30% will suffer 3~5%, 13~18%, and 33~47% more damage than their regular counterparts, respectively.

A Study on the Static Eccentricities of Buildings Designed by Different Design Eccentricities (설계편심의 크기에 따른 비틀림 비정형 건물의 최종 정적편심 크기의 비교에 관한 연구)

  • Lee, Kwang-Ho;Jeong, Seoung-Hoon
    • Journal of the Earthquake Engineering Society of Korea
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    • v.16 no.5
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    • pp.33-40
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    • 2012
  • To reduce the vulnerability of torsional irregular buildings caused by seismic loads, the torsional amplification factor was introduced by the seismic code. This factor has been applied differently in a variety of seismic codes. In this study, the final static eccentricity, and the lateral and torsional stiffness ratios of buildings designed with different design eccentricities were compared. The increment of the torsional amplification factor resulted in a decrement of the final static eccentricity of the building. However, after reaching the maximum value of this factor, the final static eccentricity of the building increased again. The final static eccentricity of the building designed by multiplying the sum of the inherent and accidental eccentricity by the torsional amplification factor was zero or had a minus value, depending to the position of the vertical element.

Evaluation of the seismic performance of off-centre bracing system with ductile element in steel frames

  • Bazzaz, Mohammad;Kheyroddin, Ali;Kafi, Mohammad Ali;Andalib, Zahra
    • Steel and Composite Structures
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    • v.12 no.5
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    • pp.445-464
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    • 2012
  • In order to evaluate the dynamic behavior of passive energy dissipation system, two steps need to be considered for prediction of structural response in the presence of ductile element in an off-centre bracing system. The first is a detailed analysis of the proposed ductile element and the second is the effect of this ductile element on an off-centre bracing system. The use of ductile bracing system is expanding in steel structures in order to increase the force reduction factor. Therefore, regarding the nonlinear behavior of steel material used in an off-centre bracing systems and using ductile element in OBS bracing systems, the seismic evaluation of the mentioned systems seems to be necessary. This paper aims to study linear and nonlinear behavior of steel frames with off-centre bracing system and ductile element, in order to get the best position of these bracing elements. To achieve this purpose, the modeling has been done with ANSYS software. The optimum eccentricity has been obtained by modeling three steel frames with different eccentricities and evaluating the results of them. The analytical results showed that the model OBS-C with 0.3 eccentricities has higher performance among the models.

Effects of Mount Eccentricity and External Force Eccentricity on the Vibration Characteristics of Naval Shipboard Equipments Supported by Elastic Mounts (마운트편심과 기진력편심이 함정탑재장비의 진동특성에 미치는 영향)

  • Lee, Hyun Yup;Lee, Chung Hyun;Ruy, Wonsun
    • Journal of the Society of Naval Architects of Korea
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    • v.54 no.6
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    • pp.447-452
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    • 2017
  • A rigid body supported by 4 linear springs has been analyzed, to investigate the effects of eccentricities on the vibration responses for naval shipboard equipments supported by elastic mounts. Considering mount eccentricity (the location of the center of spring reaction forces relative to the mass center) and excitation force eccentricity (the location of the center of the excitation force relative to the mass center), the vibration phenomena have been formulated and discussed. Also, the effects of the eccentricities have been evaluated and discussed for the elastically mounted naval shipboard equipment. Results show that the mount eccentricity has little effects on the structure-borne noise above the natural frequency of the system, however the excitation force eccentricity has significant effects all over the frequency range.

A Study on the Relationship between Earthquake Damage and the Design Eccentricity of Building with Planar Irregularity (평면 비정형 건물의 설계편심과 지진 손상도의 상관관계에 관한 연구)

  • Lee, Kwang Ho;Jeong, Seong Hoon
    • Journal of the Earthquake Engineering Society of Korea
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    • v.17 no.5
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    • pp.237-243
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    • 2013
  • In the Korean Building Code (KBC), the Design Eccentricity involves the torsional amplification factor (TAF), and the inherent and accidental eccentricities. When a structure of less than 6-stories and assigned to seismic design category C or D is designed using equivalent static analysis method, both KBC-2006 and KBC-2009 use the TAF but apply different calculation methods for the of design eccentricity. The design eccentricity in KBC-2006 is calculated by multiplying the sum of inherent eccentricity and accidental eccentricity at each level by a TAF but that in KBC-2009 is calculated by multiplying only the accidental eccentricity by a TAF. In this paper, the damage indices of a building with planar structural irregularity designed by different design eccentricities are compared and the relationship between the earthquake damage and design eccentricity of the building is evaluated. On the basis of this study, the increment of design eccentricity results in the decrement of final eccentricity and global damage index of structure. It is observed that design eccentricity in KBC-2006 reduces the vulnerability of torsional irregular building compared to design eccentricity in KBC-2009.

Non linear seismic response of a low reinforced concrete structure : modeling by multilayered finite shell elements

  • Semblat, J.F.;Aouameur, A.;Ulm, F.J.
    • Structural Engineering and Mechanics
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    • v.18 no.2
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    • pp.211-229
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    • 2004
  • The main purpose of this paper is the numerical analysis of the non-linear seismic response of a RC building mock-up. The mock-up is subjected to different synthetic horizontal seismic excitations. The numerical approach is based on a 3D-model involving multilayered shell elements. These elements are composed of several single-layer membranes with various eccentricities. Bending effects are included through these eccentricities. Basic equations are first written for a single membrane element with its own eccentricity and then generalised to the multilayered shell element by superposition. The multilayered shell is considered as a classical shell element : all information about non-linear constitutive relations are investigated at the local scale of each layer, whereas balance and kinematics are checked afterwards at global scale. The non-linear dynamic response of the building is computed with Newmark algorithm. The numerical dynamic results (blind simulations) are considered in the linear and non linear cases and compared with experimental results from shaking table tests. Multilayered shell elements are found to be a promising tool for predictive computations of RC structures behaviour under 3D seismic loadings. This study was part of the CAMUS International Benchmark.