• 제목/요약/키워드: soil flexibility

검색결과 72건 처리시간 0.02초

Inelastic behavior of systems with flexible base

  • Fernandez-Sola, Luciano R.;Huerta-E catl, Juan E.
    • Earthquakes and Structures
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    • 제14권5호
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    • pp.411-424
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    • 2018
  • This study explores the inelastic behavior of systems with flexible base. The use of a single degree of freedom system (ESDOF) with equivalent ductility to represent the response of flexible base systems is discussed. Two different equations to compute equivalent ductility are proposed, one which includes the contribution of rigid body components, and other based on the overstrength of the structure. In order to asses the accuracy of ESDOF approach with the proposed equations, the behavior of a 10-story regular building with reinforced concrete (RC) moment resisting frames is studied. Local and global ductility capacity and demands are used to study the modifications introduced by base flexibility. Three soil types are considered with shear wave velocities of 70, 100 and 250 m/s. Soil-foundation stiffness is included with a set of springs on the base (impedance functions). Capacity curves of the building are computed with pushover analysis. In addition, non linear time history analysis are used to asses the ductility demands. Results show that ductility capacity of the soil-structure system including rigid body components is reduced. Base flexibility does not modify neither yield and maximum base shear. Equivalent ductility estimated with the proposed equations is fits better the results of the numerical model than the one considering elastoplastic behavior. Modification of beams ductility demand due to base flexibility are not constant within the structure. Some elements experience reduced ductility demands while other elements experience increments when flexible base is considered. Soil structure interaction produces changes in the relation between yield strength reduction factor and structure ductility demand. These changes are dependent on the spectral shape and the period of the system with fixed and flexible base.

Seismic response of soil-structure interaction using the support vector regression

  • Mirhosseini, Ramin Tabatabaei
    • Structural Engineering and Mechanics
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    • 제63권1호
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    • pp.115-124
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    • 2017
  • In this paper, a different technique to predict the effects of soil-structure interaction (SSI) on seismic response of building systems is investigated. The technique use a machine learning algorithm called Support Vector Regression (SVR) with technical and analytical results as input features. Normally, the effects of SSI on seismic response of existing building systems can be identified by different types of large data sets. Therefore, predicting and estimating the seismic response of building is a difficult task. It is possible to approximate a real valued function of the seismic response and make accurate investing choices regarding the design of building system and reduce the risk involved, by giving the right experimental and/or numerical data to a machine learning regression, such as SVR. The seismic response of both single-degree-of-freedom system and six-storey RC frame which can be represent of a broad range of existing structures, is estimated using proposed SVR model, while allowing flexibility of the soil-foundation system and SSI effects. The seismic response of both single-degree-of-freedom system and six-storey RC frame which can be represent of a broad range of existing structures, is estimated using proposed SVR model, while allowing flexibility of the soil-foundation system and SSI effects. The results show that the performance of the technique can be predicted by reducing the number of real data input features. Further, performance enhancement was achieved by optimizing the RBF kernel and SVR parameters through grid search.

기능성 향상을 위한 환경미화원복 설계 (Construction of Street Cleaner Uniform for the Funtional Improvement)

  • 허진경;최혜선
    • 한국의류학회지
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    • 제30권8호
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    • pp.1178-1187
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    • 2006
  • The purpose of this study is to conduct a questionnaire survey on the actual conditions of the working uniform and protective equipment put on by street cleaners, then to identify their inconvenience and problems and to draw solutions to improve them, and finally to design a spring-and-autumn street cleaner uniform which has enhanced functionalities such as motional flexibility, safety and soil proof. The questionnaire survey of this study was done by street cleaners who were in charge of street cleaning and collecting the recyclable waste. The result of this study, easily worn-out parts of the working clothing were the sleeve hems and the front part on the upper uniform, and the trouser hems and zipper on the lower uniform. Easily soiled parts were the sleeve hems, parts of arm on the upper uniform, and the trouser hems and knee parts on the lower uniform. Based on the results of the questionnaire survey, the sample uniforms were designed in consideration of material, design and pattern. A soil-proof material was used for easily soiled parts such as sleeve hems, knee parts and trouser hems. Reflective material was applied to the parts such as chest, back and the side lines of sleeves and trousers to raise visibility in working and to ensure safety. A crease was given to each side of the back. The height of sleeve cap was lowered to lift the motional flexibility of back and arm parts. Darts were applied to elbow and knee parts for a three-dimensional design. Gussets were inserted in the thigh part to give it activity. Then quantitative evaluation and a sensory evaluation, which was composed of outward appearance, motional flexibility and fitness for field operation, were conducted. According to these evaluations, the sample uniform was found to be more satisfactory than current uniform.

동적 수치해석을 통한 베이스먼트의 지진토압에 대한 매개변수 연구 (Parametric Study on Seismic Earth Pressure Through Dynamic Numerical Analyses of Basements)

  • 박두희;이충현
    • 한국지반공학회논문집
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    • 제40권4호
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    • pp.19-32
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    • 2024
  • 동적 토압 해석은 지하 구조물의 내진 설계에서 핵심적인 파라미터이다. 그러나 기존 토압식들은 지반과 구조물의 상호작용, 상대적 유연성 비율(F) 및 구조물의 래킹 비율(R), 종횡비(L/H) 등 중요한 변수들을 종합적으로 고려하지 않은 것들이 대다수이다. 본 연구의 목적은 이러한 매개변수들이 동적 토압에 미치는 영향을 확인하여 기존의 옹벽 토압식의 신뢰도를 평가하는 것이며, 이를 위해 베이스먼트에 대해 동적 수치해석을 통한 매개변수 연구를 수행하였다. 그 결과, 종횡비가 높고 유연성이 낮은 구조물이 종횡비가 낮고 유연성이 높은 구조물보다 지진 토압에 더 취약하다는 사실을 확인하였다. 따라서 베이스먼트의 지진 토압 또는 동적 토압 추정에 있어 종횡비 및 유연비를 고려하는 것이 필요하고, 기존 옹벽의 토압식 적용 시 주의가 필요하다고 판단된다.

Natural stiffness matrix for beams on Winkler foundation: exact force-based derivation

  • Limkatanyu, Suchart;Kuntiyawichai, Kittisak;Spacone, Enrico;Kwon, Minho
    • Structural Engineering and Mechanics
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    • 제42권1호
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    • pp.39-53
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    • 2012
  • This paper presents an alternative way to derive the exact element stiffness matrix for a beam on Winkler foundation and the fixed-end force vector due to a linearly distributed load. The element flexibility matrix is derived first and forms the core of the exact element stiffness matrix. The governing differential compatibility of the problem is derived using the virtual force principle and solved to obtain the exact moment interpolation functions. The matrix virtual force equation is employed to obtain the exact element flexibility matrix using the exact moment interpolation functions. The so-called "natural" element stiffness matrix is obtained by inverting the exact element flexibility matrix. Two numerical examples are used to verify the accuracy and the efficiency of the natural beam element on Winkler foundation.

지반의 상호작용을 고려한 전면기초의 해석기법 개발 (Development of Analysis Method for Mat Foundations Considering Coupled Soil Springs)

  • 이재환;정상섬;이준규
    • 한국지반공학회논문집
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    • 제30권12호
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    • pp.41-49
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    • 2014
  • 본 연구에서는 기존 근사해석 프로그램의 간편함을 유지하면서 보다 정밀성이 확보된 3차원 근사해석기법(YS-MAT)을 개발하였다. 전면기초는 6개의 자유도를 가진 평면쉘 요소로 모델링하여 기초의 연성거동을 고려할 수 있도록 하였으며, 지반스프링의 상호작용을 고려할 수 있도록 하였다. 기존의 해석기법, 유한요소해석 및 현장계측값과의 비교 분석 결과, 본 해석기법이 대단면 전면기초의 침하 거동을 비교적 정확히 산정하는 것으로 판단되며, 이러한 검증을 토대로 실제 전면기초 예비설계에 적용 가능함을 확인할 수 있었다.

현행 도로교시방서의 지반계수에 대한 공학적 영향평가 (Engineering Impact Assessment of the Site Coefficients In the Current Highway Bridge Code of Korea)

  • 조양희
    • 한국지진공학회:학술대회논문집
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    • 한국지진공학회 1998년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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    • pp.89-97
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    • 1998
  • This study is intended to investigate the seismic responses of bridge structures considering site effects. The site effects in the seismic analysis of bridge structures were classified into two parts. At first, the seismic responses of the structures on each "soil profile types" of the code were evaluated in accordance with code-specified method and compared with results of time-history analysis method. And next, as a second stage of the study, the responses of the two different soil with considerably different soil properties, even though they are classified to the same "soil profile types" of the code, were evaluated and compared each other. The first part of study is purposed to evaluate the applicability of code-specified method, while the other part is purposed to find the variance of the seismic responses from the different soil sites in the same soil profile types of the code. For the analysis, two major methods of the code, single-mode spectral anaysis and multi-mode spectral analysis, were used and the time-history analysis method which is expected to give more accurate responses was also used for the comparison purposes. For the time-history analysis, time-domain analysis technique of the lumped-mass model with frequency-independent soil springs and dampers was adopted and artificially generated spectra of the code was used as input motion. As the results of the study, the code specified methods for the seismic responses considering the site effects were verified to give the results in conservative side for the most of the cases. However, for the structures on the site with considerable flexibility, the responses of the bridge girders or deckplates by the code methods both in section forces and horizontal movement responses, may have much smaller values than the actual responses. Therefore, more detailed analysis considering the flexibility of the base soil may be required to have more reasonable results in girder responses.in girder responses.

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교대를 지지하는 군말뚝의 캡강성효과 (Effect of Pile Cap Flexibility on the Response of Pile Group Supported Column)

  • 정상섬;원진오;김영호
    • 한국지반공학회논문집
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    • 제23권9호
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    • pp.39-49
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    • 2007
  • 본 연구에서는 수치해석을 통해 말뚝캡의 강성에 따른 거동차이를 분석하였다. 따라서 강성캡과 연성캡을 선정하여 상부교각과 하부군말뚝기초를 일체화하여 일련의 해석을 수행하였다. 해석 시 캡강성에 영향을 주는 캡의 탄성계수와 두께, 상부 교각길이, 지반반력, 그리고 말뚝직경 등을 고려하였다. 본 연구결과 군말뚝내 개별말뚝에 작용하는 하중은 말뚝캡의 강성에 크게 좌우되었으며 그 결과, 연성캡 해석결과는 강성캡에 비하여 수평하중과 휨모멘트가 상대적으로 크게 발생하므로 좀 더 보수적인 설계가 가능하리라 판단된다.

지반-구조물 상호작용을 고려한 터널 구조물의 동적 해석 (Dynamic Analysis of Tunnel Structures Considering Soil-Structure Interaction)

  • 김현중;박장호;신영석
    • 한국안전학회지
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    • 제20권1호
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    • pp.101-106
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    • 2005
  • When a underground structure is constructed at the site composed of soft soil, the behavior of a underground structure Is much affected by the motion of soft soil. Therefore, the effect of soil-structure interaction is an important consideration in the design of a underground structure such as tunnel at the site composed of soft soil. This paper presents the results of the study on dynamic response of tunnel structures and soil-structure interaction effects. The computer program SASSI was used in seismic analysis of tunnel structures because it is more capable of analyzing dynamic response or structures considering soil-structure interaction. As regards the results, the flexibility of surrounding soil affects dynamic response characteristics of tunnel structures and response of tunnel structures can be amplified.

보강토의 시공중 거동 평가 (Behavior of a Reinforced Retaining Wall During Construction)

  • 노한성;최영철;백종은;김영남
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2000년도 가을 학술발표회 논문집
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    • pp.95-100
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    • 2000
  • When compared with conventional retaining wall system, there are many advantages to reinforced soil such as cost effectiveness, flexibility and so on. The use of reinforced soil have been increased in the last 17 years in Korea. In this study, a full-scale reinforced soil with rigid facing were constructed to investigate the behavior of reinforcing system. The results of soil pressure and strain of reinforcement during construction are described. The influence of compaction on soil pressure and strain of reinforcement is addressed. The results show that lateral earth pressures on the wall are active state during backfill. It is obtained that the lateral soil pressure depends on the installation condition of pressure cell and construction condition. It is also observed that maximum tensile strains of reinforcement are located on 50cm to 150cm from the wall. Long-term measurement will be followed to verify the design assumptions with respect to the distribution of lateral stress in the reinforcement

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