• 국제초고층학회논문집
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• 제1권1호
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• pp.37-51
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• 2012

New generation of tall and complex buildings systems are now introduced that are reflective of the latest development in materials, design, sustainability, construction, and IT technologies. While the complexity in design is being overcome by the availability and advances in structural analysis tools and readily advanced software, the design of these buildings are still reliant on minimum code requirements that yet to be validated in full scale. The involvement of the author in the design and construction planning of Burj Khalifa since its inception until its completion prompted the author to conceptually develop an extensive survey and real-time structural health monitoring program to validate all the fundamental assumptions mad for the design and construction planning of the tower. The Burj Khalifa Project is the tallest structure ever built by man; the tower is 828 meters tall and comprises of 162 floors above grade and 3 basement levels. Early integration of aerodynamic shaping and wind engineering played a major role in the architectural massing and design of this multi-use tower, where mitigating and taming the dynamic wind effects was one of the most important design criteria established at the onset of the project design. Understanding the structural and foundation system behaviors of the tower are the key fundamental drivers for the development and execution of a state-of-the-art survey and structural health monitoring (SHM) programs. Therefore, the focus of this paper is to discuss the execution of the survey and real-time structural health monitoring programs to confirm the structural behavioral response of the tower during construction stage and during its service life; the monitoring programs included 1) monitoring the tower's foundation system, 2) monitoring the foundation settlement, 3) measuring the strains of the tower vertical elements, 4) measuring the wall and column vertical shortening due to elastic, shrinkage and creep effects, 5) measuring the lateral displacement of the tower under its own gravity loads (including asymmetrical effects) resulting from immediate elastic and long term creep effects, 6) measuring the building lateral movements and dynamic characteristic in real time during construction, 7) measuring the building displacements, accelerations, dynamic characteristics, and structural behavior in real time under building permanent conditions, 8) and monitoring the Pinnacle dynamic behavior and fatigue characteristics. This extensive SHM program has resulted in extensive insight into the structural response of the tower, allowed control the construction process, allowed for the evaluation of the structural response in effective and immediate manner and it allowed for immediate correlation between the measured and the predicted behavior. The survey and SHM programs developed for Burj Khalifa will with no doubt pioneer the use of new survey techniques and the execution of new SHM program concepts as part of the fundamental design of building structures. Moreover, this survey and SHM programs will be benchmarked as a model for the development of future generation of SHM programs for all critical and essential facilities, however, but with much improved devices and technologies, which are now being considered by the author for another tall and complex building development, that is presently under construction.

• Geomechanics and Engineering
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• 제31권5호
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• pp.489-503
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• 2022

A 1257-m-long irregular deep foundation pit located in the central of Nanjing, China was constructed using the combined full-width and half-width top-down method. Based on the long-term field monitoring data, this study analyzed the evolution characteristics of the vertical movement of the columns, internal force of the struts, and axial force of the structural beam and slab. The relevance of the three mentioned above and their relationship with the excavation process, structural system, and geological conditions were also investigated. The results showed that the column uplift was within the range of 0.08% to 0.22% of the excavation depth, and the embedded depth ratio of the diaphragm wall and the bottom heave affected significantly on the column uplift. The differential settlement between the column and diaphragm wall remained unchanged after the base slab was cast. The final settlement of the diaphragm wall was twice the column uplift. The internal force of the struts did not varied monotonically but was related to numerous factors such as the excavation depth, number of struts, and environmental conditions. Additionally, the dynamic force and deformation of the columns, beams, and slabs were analyzed to investigate the inherent relationship and variation patterns of the responses of different parts of the structure.

• Structural Monitoring and Maintenance
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• 제9권4호
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• pp.359-371
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• 2022

Bridges are critical to the civil engineering infrastructure network as they facilitate movement of people, the transportation of goods and services. Given the aging of bridge infrastructure, federal officials mandate visual inspections biennially to identify necessary repair actions which are time, cost, and labor-intensive. Additionally, the expansion joints of bridges are rarely monitored due to cost. However, expansion joints are critical as they absorb movement from thermal effects, loadings strains, impact, abutment settlement, and vehicle motion movement. Thus, the need to monitor bridge expansion joints efficiently, at a low cost, and wirelessly is desired. This paper addresses bridge joint monitoring needs to develop a cost-effective, real-time wireless system that can be validated in a full-scale bridge structure. To this end, a wireless expansion joint monitoring was developed using commercial-off-the-shelf (COTS) sensors. An in-service bridge was selected as a testbed to validate the performance of the developed system compared with traditional displacement sensor, LVDT, temperature and humidity sensors. The short-term monitoring campaign with the wireless sensor system with the internet protocol version 6 over the time slotted channel hopping mode of IEEE 802.15.4e (6TiSCH) network showed reliable results, providing high potential of the developed system for effective joint monitoring at a low cost.

• 수산경영론집
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• 제48권3호
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• pp.15-32
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• 2017

This article's aim is to review the jurisprudence which has emerged pursuant to the international dispute settlement provisions and to provide a provisional expectation as to the future of international dispute settlement under "UNCLOS". Globally, marine fisheries play an important role in ocean biodiversity and the food security of millions of people, providing a vital source of high-quality dietary protein and supporting individuals' livelihoods and income. In the 1982 Convention, the establishment of co-operative mechanisms for effective monitoring, control, surveillance and enforcement, decision-making procedures facilitating the adoption of such measures of conservation and management, and the promotion of the peaceful settlement of disputes are called for. In this study, 'Northeast Asian Sea' means that the Yellow/East China Sea, the East Sea, the Ohotsk Sea, the Kamchaka Sea, the Alaska Sea, and the Bering Sea surrounded by Korea, China, Japan, Russia, U.S.A. and Canada including their EEZs. There are several bilateral fisheries agreements existing in Northeast Asian area, the Fisheries Agreement between Republic Korea and Japan, between Republic of Korea and China, between China and Japan, between Republic Korea and U.S.A., between Republic Korea and Russia, between Russia and Japan, And there are several regional fisheries organizations existing in Northeast Asian area, for example NPAFC(Convention for the Conservation of Anadromous Stocks in the North Pacific Ocean), CBSPC (Convention on the Central Bering Sea Pollack Conservation), PICES(North Pacific Marine Science Organization), NPFC(North Pacific Fishery Commi-ssion) etc. It analyzed the proliferation of bilateral treaties and multilateral treaties due to the adoption of the EEZ in Northeast Asia reviewed the strengthening of management rights on the high seas marine living resources and marine environment preservation of regional fisheries organizations. In view of the changes in the international fisheries mechanism this paper suggested the future direction of the country in overseas fisheries. We concluded as follows. We shall apply bilateral treaties first, regional fisheries organizations' treaties secondly, and provisions under "UNCLOS" for dispute settlement last.

• 한국터널지하공간학회 논문집
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• 제18권1호
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• pp.61-74
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• 2016

본 논문에서는 화강풍화대를 통과하는 슬러리 TBM 굴진 중 지표 침하 및 체적손실 산정에 관한 사례 연구를 수행하였다. 터널 천단 침하 계측 결과로부터 TBM 굴진 단계별 침하 발생 경향을 분석하였고, 횡방향 지표 침하 트라프로부터 굴진 중 체적손실 및 트라프 변수를 산정하였다. 또한, 체적손실 산정 모델을 이용하여 지반 특성과 굴진 중 측정된 기계데이터가 반영된 굴진 단계별 체적손실을 산정하였으며, 이를 실제 계측 결과와 비교 분석하였다. 슬러리 TBM의 경우 대부분의 지표침하는 쉴드 본체 통과 및 뒤채움 주입 이후 발생하는 것으로 나타났고 문헌에 보고된 총 체적손실 및 트라프 곡선 형태가 확인되었다. 실제 굴진 중 체적손실은 굴진 단계별로 쉴드손실 예측값의 90%, 테일부 손실 예측값의 60% 수준으로 분석되었고, 쉴드 손실에 비해 테일부 손실의 편차가 큰 것으로 나타났다.

• Geomechanics and Engineering
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• 제34권4호
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• pp.397-408
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• 2023

Pipe pile walls are commonly used as retaining structures for excavation projects, particularly in densely populated coastal cities such as Hong Kong. Pipe pile walls are preferred in reclaimed land due to their cost-effectiveness and convenience for installation. However, the pre-bored piling techniques used to install pipe piles can cause significant ground disturbance, posing risks to nearby sensitive structures. This study reports a well-documented case history in a reclamation site, and it was found that pipe piling could induce ground settlement of up to 100 mm. Statutory design submissions in Hong Kong typically specify a ground settlement alarm level of 10 mm, which is significantly lower than the actual settlement observed in this study. In addition, lateral soil movement of approximately 70 mm was detected in the marine deposit. The lateral soil displacement in the marine deposit was found to be up to 3.4 and 3.1 times that of sand fill and CDG, respectively, mainly due to the relatively low stiffness of the marine deposit. Based on the monitoring data and site-investigation data, a 3D numerical analysis was established to back-analyze soil movements due to the installation of the pipe pile wall. The comparison between measured and computed results indicates that the equivalent ground loss ratio is 20%, 40%, and 20% for the fill, marine deposit and CDG, respectively. The maximum ground settlement increases with an increase in the ground loss ratio of the marine deposit, whereas the associated influence radius remains stationary at 1.2 times the pipe pile wall depth (H). The maximum ground settlement increases rapidly when the thickness of marine deposit is less than 0.32H, particularly for the ground loss ratio of larger than 40%. This study provides new insights into the pipe piling construction in reclamation sites.

• 한국구조물진단유지관리공학회 논문집
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• 제27권5호
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• pp.40-48
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• 2023

본 논문에서는 항만 계류시설 중 대표적인 구조형식인 케이슨식 안벽의 장기 거동 특성을 분석하기 위하여, 센서 기반 모니터링 시스템을 구축하고, 약 10개월간의 데이터를 검토하였다. 문헌을 바탕으로 항만시설물의 피해 원인 및 유형을 분류하였으며, 이에 적합한 센서 및 계측 시스템을 선정, 현장에 설치하여 주기적으로 데이터를 확보하였다. 확보한 데이터는 LTE 통신망으로 서버에 전달 및 저장된다. 현장상황을 고려하여 경사계, 이격거리계, 침하계를 설치하였으며, 서로 다른 케이슨간의 비교를 위하여 2개 함을 대상으로 센서를 부착하였다. 계측된 센서 데이터와 기온 및 인근 해역에서 계측된 조위 데이터의 상관성을 비교하였다. 이격거리계와 침하계의 경우 온도에 따른 영향이 지배적으로 나타난 반면, 경사계는 상대적으로 덜 민감한 경향을 보였다. 온도가 약 50도 변화 할 때, 변위는 10mm, 침하는 2mm, 기울기는 0.1도 가량 변화하였다. 한편, 조위 데이터와는 뚜렷한 상관성을 보이지 않았으며, 추후 심도있는 분석이 필요하다고 판단된다. 계측된 데이터의 특성을 바탕으로 중력식 안벽에 이상상태가 발생하였을 때 이를 탐지할 수 있는 알고리즘을 개발할 수 있으며, 이를 위한 데이터베이스를 구축하였다. 중력식 안벽 대상 지속적인 장기 데이터 확보 및 분석을 통하여, 재해 및 재난 발생 시 구조물의 안전성 및 사용성을 객관적으로 평가할 수 있을 것으로 기대된다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.1007-1013
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• 2004

A three-arch NATM tunnel with a total length of 53.5m has been constructed for a metropolitan subway station in Daejon, Korea. The tunnel, whose crown is located 22m below the ground, crosses the old Daejon station underneath. Since the tunnel comprises a very large section (10${\times}$28 m; largest in Korea), it shows complicated mechanical behaviors, especially near portal, due to its short length relative to width. As far as its construction step is concerned, the center tunnel is excavated with pre-excavated pilot tunnel, which is a unique feature of this tunnel (first in Korea) to secure safety during construction and prevent excessive settlements. The both side tunnels are then excavated along with the center tunnel. Since significant amount of settlement was predictable from the design stage, extensive monitoring was performed during construction. During excavation of the side tunnels, unexpected large settlements up to ${\~}$140mm (estimated 41.8 mm at design stage) was measured at the center tunnel. In this paper, we study the causes of this unusually large ground settlement. We believe that the extra-wide tunnel excavation increases the stress influence zone of portal in longitudinal direction and consequently add more settlements to the existing due to excavation and consolidation.

• Structural Monitoring and Maintenance
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• 제9권1호
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• pp.1-27
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• 2022

Extensive laboratory tests were conducted to investigate the effect of load amplitude, geogrid position, and number of geogrid layers, thickness of ballast layer and clay stiffness on behavior of reinforced ballast layer and induced strains in geogrid. A half full-scale railway was constructed for carrying out the tests, the model consists of two rails 800 mm in length with three wooden sleepers (900 mm × 10 mm × 10 mm). The ballast was overlying 500 mm thickness clay in two states, soft and stiff state. Laboratory tests were conducted to investigate the response of the ballast and the clay layers where the ballast was reinforced by a geogrid. Settlement in ballast and clay, soil pressure and pore water pressure induced in the clay were measured in reinforced and unreinforced ballast cases. It was concluded that the effect of frequency on the settlement ratio is almost constant after 500 cycles. This is due to that the total settlement after 500 cycles, almost reached its peak value, which means that the ballast particles become very close to each other, so the frequency is less effective for high contact particles forces. The average maximum vertical stress and pore water pressure increased with frequency.

• 한국산학기술학회논문지
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• 제19권4호
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• pp.8-16
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• 2018

본 논문의 목적은 고속철도 콘크리트 궤도 및 노반 측정 데이터(노반압력, 진동가속도, 탄성변위 등)를 이용하여 토공노반의 장기거동을 분석하고 궤도 노반의 장기성능을 평가하고자 하는데 있다. 최근 고속철도 궤도 형식이 콘크리트 슬래브로 채택되고 있다. 그러나 콘크리트 궤도는 노반 침하에 취약하다. 자갈궤도의 경우 노반이 침하되어도 유지보수로 원상복구가 용이하다. 반면에 콘크리트 궤도의 경우 노반의 과도한 침하가 발생하면 도상 및 침목에 균열이 지속적으로 발생되고 사용성이 크게 저하된다. 이와 같은 이유로 부분보수만으로 원상복구가 어렵다. 본 논문에서는 운영 중 콘크리트 궤도에 대하여 건설 초부터 매설된 센서의 측정 데이터를 개통 후 약 3년까지 모니터링하여 장기성능평가를 수행하였다. 성능평가 방법은 열차별 궤도 토공노반 및 장기 궤도 노반 성능평가, 장기침하에 따른 궤도 노반 성능 영향 분석 및 장기 침하 영향인자 분석 등이다. 열차별 궤도 노반 성능평가에서는 KTX-산천중련의 노반응답이 가장 컸다. 장기 궤도 노반 성능평가 결과는 측정항목이 기준치이내로 측정되었다. 장기침하에 따른 궤도 노반 성능영향 평가는 TCL처짐은 침하와 깊은 연관이 있는 것으로 분석되었다. 장기침하의 외부영향인자 분석을 통해 함수비와 지하수위의 영향성을 확인하였다. 이와같은 방법을 통해 궤도상 토공노반의 안정성을 확보할 수 있을 것으로 사료된다.