• Title/Summary/Keyword: vulnerable foundations

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Performance-based framework for soil-structure systems using simplified rocking foundation models

  • Smith-Pardo, J. Paul
    • Structural Engineering and Mechanics
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    • v.40 no.6
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    • pp.763-782
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    • 2011
  • Results from nonlinear time-history analyses of wall-frame structural models indicate that the condition of vulnerable foundations -for which uplifting and reaching the bearing capacity of the supporting soil can occur before yielding at the base of the shear walls- may not be necessarily detrimental to the drift response of buildings under strong ground motions. Analyses also show that a soil-foundation system can inherently have deformation capacity well in excess of the demand and thus act as a source of energy dissipation that protects the structural integrity of the shear walls.

Rotational capacity of shallow footings and its implication on SSI analyses

  • Blandon, Carlos A.;Smith-Pardo, J. Paul;Ortiz, Albert
    • Earthquakes and Structures
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    • v.8 no.3
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    • pp.591-617
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    • 2015
  • Standards for seismic assessment and retrofitting of buildings provide deformation limit states for structural members and connections. However, in order to perform fully consistent performance-based seismic analyses of soil-structure systems; deformation limit states must also be available for foundations that are vulnerable to nonlinear actions. Because such limit states have never been established in the past, a laboratory testing program was conducted to study the rotational capacity of small-scale foundation models under combined axial load and moment. Fourteen displacement-controlled monotonic and cyclic tests were performed using a cohesionless soil contained in a $2.0{\times}2.0{\times}1.2m$ container box. It was found that the foundation models exhibited a stable hysteretic behavior for imposed rotations exceeding 0.06 rad and that the measured foundation moment capacity complied well with Meyerhof's equivalent width concept. Simplified code-based soil-structure analyses of an 8-story building under an array of strong ground motions were also conducted to preliminary evaluate the implication of finite rotational capacity of vulnerable foundations. It was found that for the same soil as that of the experimental program foundations would have a deformation capacity that far exceeds the imposed rotational demands under the lateral load resisting members so yielding of the soil may constitute a reliable source of energy dissipation for the system.

Study on safety early-warning model of bridge underwater pile foundations

  • Xue-feng Zhang;Chun-xia Song
    • Structural Monitoring and Maintenance
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    • v.10 no.2
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    • pp.107-116
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    • 2023
  • The health condition of of deep water high pile foundation is vital to the safe operation of bridges. However, pier foundations are vulnerable to damage in deep water due to exposure to sea torrents and corrosive environments over an extended period. In this paper, combined with aninvestigation and analysis of the typical damage characteristics of main pier group pile foundations, we study the safety monitoring and real-time early warning technology of the deep water high pile foundations, we propose an early warning index item and early warning threshold of deep water high pile foundation by utilizing a numerical simulation analysis and referring to domestic and foreign standards and literature. First, we combine the characteristics of structures and draw on more mature evaluation theories and experience in civil engineering-related fields such as dam and bridge engineering. Then, we establish a scheme consisting of a Early Warning Index Systemand evaluation model based on the analytic hierarchy process and constant weight evaluation method and apply the research results to a project based on the Jiashao bridge in Zhejiang province, China. Finally, we verify the rationality and reliability of the Early Warning Index Systemof the Deep Water High Pile Foundations.

Development of preventive System for Accident Causing by Human Error in Small Manufacturing Industries of Chemical Products (중소화학제품 제조업의 인적오류 사고예방 시스템 개발)

  • 김두환
    • Journal of the Korean Professional Engineers Association
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    • v.34 no.3
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    • pp.22-27
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    • 2001
  • About 70% -80% of the serious injury that occure in the chemical product small manufacturing industries is caused by human error. but technical development for analysis and inspection to preestimate and exclude such human error is still insufficient. Small - to - medium sited enterprises are economically vulnerable and technical foundations for safety management is week Under such circumstances development of easy to use computerized support programs that can be operated without the help of professioanals are keenly needed.

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Seismic Design of Highway Bridges using by Bridge Bearing (교량받침을 이용한 교량구조물의 내진설계)

  • 전규식;이병진;조해진;정명호
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.04b
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    • pp.439-446
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    • 1998
  • Earthquake damage civil engineering structures every year in the world and bridges are no exception. Bridge structures have proven to be vulnerable to earthquake, sustaining damage to substructure and foundation and being totally destroys as superstructures collapse from their supporting elements. The poor seismic performance of bridge structures is surprising in view of the substantial advance made in design and construction for vertical load. Recently, bridge spans have been pushed further than before, alignment has become increasingly complex and aesthetic requirement have been become more demanding. To reduce the seismic force and to improve the safety of the advanced bridges, the bridge bearings which are the substructures and foundations and their connections to the superstructure become more important and critical elements. Therefore, the functions about seismic devices to be using as bridge bearing are discussed.

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Strengthening method against Overturn of Plain Concrete Gravity Pier for Open-Steel-Plate-Girder Railway Bridges (철도판형교 무근콘크리트 교각의 전도 보강기법)

  • Lee, Jun-S.;Choi, Eun-Soo;Rhee, In-Kuy;Lee, Joo-B.
    • Proceedings of the KSR Conference
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    • 2007.11a
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    • pp.1165-1173
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    • 2007
  • Open-Steel-Plate-Girder railway bridges, in general, have plain concrete gravity pier without piles at foundations. Such piers are vulnerable to be overturned against braking forces and ground shakings during an earthquake. Thus, this study suggests a strengthening method using earth anchors to improve the resistance of plain concrete gravity piers to the overturn of themselves. Also, a filed test was performed for the as-built and the strengthened pier and the test results were compared to assess the strengthening effect. The earth anchors increased the ultimated capacity for the pier's overturn. Finally, a FE analysis was conducted using nonlinear elements for soil to understand the distribution of the soil stresses for the as-built and the strengthened pier.

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Seismic Design and Isolation Design for Highway Bridges (교량구조물의 내진설계 및 면진설계(교량 받침을 중심으로))

  • 전규식
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 1998.04a
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    • pp.115-122
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    • 1998
  • Earthquake damage civil engineering structures every year in the world and bridges are no exception. Bridge structures have proven to be vulnerable to earthquake, sustaining damage to substructure and foundation and being totally destroys as superstructures collapse from their supporting elements. The poor seismic performance of bridge structures is surprising in view of the substantial advance made in design and construction for vertical load. Recently, bridge spans have been pushed further than before, alignment has become increasingly complex and aesthetic requirement have been become more demanding. To reduce the seismic force and to improve the safety of the advanced bridges, the bridge bearings which are the substructures and foundations and their connections to the superstructure become more important and critical elements. Therefore, the functions about seismic devices to be using as bridge bearing are discussed.

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Categorization of Hazard Chemicals Potentially Discharged into Water System (수계 유출가능성이 있는 유해화학물질 분류화)

  • An, Youn-Joo;Nam, Sun-Hwa;Lee, Jae-Kwan
    • Journal of Korean Society on Water Environment
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    • v.24 no.2
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    • pp.247-259
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    • 2008
  • The utilization of a variety of hazard chemicals bears risks to human health and ecosystem. The increasing usage of various chemicals indicates the greater emission of those chemicals to water system, and the subsequent deterioration of water quality. Water system is vulnerable to many pollutants, however, there are limitations of managing a range of hazard chemicals based on insufficient legal foundations. Therefore it is needed to select hazard chemicals that can be potentially discharged into water system, and subsequently to classify a wide range of existing chemicals for better management of those chemicals. In this study, the 259 candidate chemicals of concern were selected from the lists of the toxic released inventory chemicals (148), hazard concern candidate chemicals (106), and wastewater effluent standard candidate chemicals (116). We suggested the category 1, 2, 3 and 4 of hazard chemicals potentially discharged into water system. The assessment factors considered for the classification were hazard potential, persistence and emission to water body. This work was conducted as a part of the project entitled 'Development of integrated methodology for evaluation of water environment', and the results were used to develop the monitoring lists of hazard chemicals in four major rivers in Korea.

Health Care Communications with Diverse Ethnic Groups

  • Savitri, Singh-Carlson
    • Women's Health Nursing
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    • v.16 no.4
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    • pp.419-423
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    • 2010
  • Purpose: The concept of respect is rooted in the core value of human relations, and interpersonal relationships with others. The notion of respect in these relationships is entrenched in the broader context of the processes of relationships between professionals and clients in general, along with the philosophical and ethical foundations of respect. Although nursing principles and values, such as autonomy and dignity have built their foundation of care on the concept of respect, these concepts (ie. autonomy and dignity) are still different from respect. Respect within health professional-client relationships, indicates that respect is a fundamental concept within nursing, permeating a number of other concepts that provide purposeful nursing care within the process of nurse-client relationships and respect has been discussed as an ethical and moral concept of care that addresses the values of human dignity in the nursing discipline, however research examining the client s perspectives of respect as an ethical principle of care, especially within Canada s diverse population is non-existent. There is limited research from the client s perspective addressing challenges communicating the concept of respect in relationships between health professionals and clients, specifically research directed at immigrant or the vulnerable population.

Out-of-plane seismic failure assessment of spandrel walls in long-span masonry stone arch bridges using cohesive interface

  • Bayraktar, Alemdar;Hokelekli, Emin;Halifeoglu, Meral;Halifeoglu, Zulfikar;Ashour, Ashraf
    • Earthquakes and Structures
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    • v.18 no.1
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    • pp.83-96
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    • 2020
  • The main structural elements of historical masonry arch bridges are arches, spandrel walls, piers and foundations. The most vulnerable structural elements of masonry arch bridges under transverse seismic loads, particularly in the case of out-of-plane actions, are spandrel wall. The vulnerability of spandrel walls under transverse loads increases with the increasing of their length and height. This paper computationally investigates the out-of-plane nonlinear seismic response of spandrel walls of long-span and high masonry stone arch bridges. The Malabadi Bridge with a main arch span of 40.86m and rise of 23.45m built in 1147 in Diyarbakır, Turkey, is selected as an example. The Concrete Damage Plasticity (CDP) material model adjusted to masonry structures, and cohesive interface interaction between the infill and the spandrel walls and the arch are considered in the 3D finite element model of the selected bridge. Firstly, mode shapes with and without cohesive interfaces are evaluated, and then out-of-plane seismic failure responses of the spandrel walls with and without the cohesive interfaces are determined and compared with respect to the displacements, strains and stresses.