• 한국지반공학회논문집
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• 제24권6호
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• pp.101-116
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• 2008

보강토 옹벽의 영구구조물로서의 적용성이 증가함에 따라 지속 혹은 반복하중 등 다양한 하중조건하에서 장기적인 잔류변형이 설계/시공시 주요 관점이 되고 있다. 본 연구에서는 교량구조물의 피어 및 Back-to-Back(BTB) 형태의 보강토 옹벽을 대상으로 사용하중 작용 이전에 작용시키는 선행하중이 보강토 구조물의 잔류변위를 제어에 미치는 영향을 고찰하였다. 이를 위해 모형 피어와 BTB 옹벽을 축조하여 단순재하, 지속하중, 반복하중 등 다양한 하중조건 및 시공조건에 대한 모형실험을 수행하였다. 그 결과 선행재하 공법은 다양한 하중 및 시공조건에서 잔류변위 제어에 탁월한 것으로 나타났다.

• 대한토목학회논문집
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• 제30권1A호
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• pp.35-43
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• 2010

프리캐스트 패널은 교량바닥판의 합성 구조부재로서 사용된다. 프리캐스트 패널의 횡방향 강재는 교량바닥판의 주철근 역할을 하며, 또한, 패널 상부의 현장타설 콘크리트 시공시 거푸집 대용으로 적용된다. 그러나 프리캐스트 패널의 장점을 살리기 위해서는 필연적으로 갖게 되는 구조적 특징이자 취약점이 될 수 있는 이음부 부분에 대한 이해와 지식이 필요하다. 특히, 교량바닥판은 차량하중과 같은 반복하중을 받는 구조물이므로 피로하중에 대한 이음부의 거동 및 성능 평가가 이루어져야 한다. 본 연구에서는 전단철근과 루프이음부를 갖는 프리캐스트 패널 합성바닥판의 피로실험을 수행하였다. 피로실험은 고정점 반복하중과 윤하중을 적용하여 수행되었다. 피로에 대한 현행 설계기준을 고려하고 이음부의 피로파괴 특성과 반복하중하에서의 사용성 평가를 위해 결과 분석을 수행하였다.

• Steel and Composite Structures
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• 제15권3호
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• pp.343-355
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• 2013

Shear failure and core concrete crushing at plastic hinge region are the two main failure modes of bridge piers, which can make repair impossible and cause the collapse of bridge. To avoid the two types of failure of pier, a composite pier was proposed, which was formed by embedding high strength concrete filled steel tubular (CFT) column in reinforced concrete (RC) pier. Through cyclic loading tests, the seismic performances of the composite pier were studied. The experimental results show that the CFT column embedded in composite pier can increase the flexural strength, displacement ductility and energy dissipation capacity, and decrease the residual displacement after undergoing large deformation. The analytical analysis is performed to simulate the hysteretic behavior of the composite pier subjected to cyclic loading, and the numerical results agree well with the experimental results. Using the analytical model and time-history analysis method, seismic responses of a continuous girder bridge using composite piers is investigated, and the results show that the bridge using composite piers can resist much stronger earthquake than the bridge using RC piers.

• Steel and Composite Structures
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• 제37권4호
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• pp.431-446
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• 2020

This paper presents the flexural performance of double skin composite beams (DSCBs) at different Arctic low temperatures. 12 DSCBs were prepared and tested under two-point loading at different Arctic low temperatures of 20, -30, -50, and -70℃. The studied parameters include low-temperature level (T), steel-faceplate thickness (t), shear span ratio (λ), and spacing of headed studs (S). The experimental investigations under two-point loading tests showed that flexural failure occurred to all DSCBs, even including the specimen designed with the small λ ratio of 2.9. The ultimate strength behaviours of DSCBs were improved due to the improved mechanical properties of constructional materials and the confinement on shear connectors. The DSCB subjected to two-point loading and low temperatures exhibits a five-stage working mechanism. The stiffness and strength indexes of DSCBs increase linearly with temperature and t value increasing, while decreasing as shear span ratio boosts. In the contrast, the change of S value from 150 to 200 mm has little effect on the ultimate strength behavior of DSCB.

• Steel and Composite Structures
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• 제18권4호
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• pp.925-946
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• 2015

This paper presents a new cost-effective hybrid GFRP-Concrete deck system that the GFRP panel serves as both tensile reinforcement and stay-in-place form. In order to understand the fatigue behavior of such hybrid deck, fatigue test on a full-scale specimen under sagging moment was conducted, and a series of static tests were also carried out after certain repeated loading cycles. The fatigue test results indicated that such hybrid deck has a good fatigue performance even after 3.1 million repeated loading cycles. A three-dimensional finite element model of the hybrid deck was established based on experimental work. The results from finite element analyses are in good agreement with those from the tests. In addition, flexural fatigue analysis considering the reduction in flexural stiffness and modulus under cyclic loading was carried out. The predicted flexural strength agreed well with the analytical strength from finite element simulation, and the calculated fatigue failure cycle was consistent with the result based on related S-N curve and finite element analyses. However, the flexural fatigue analytical results tended to be conservative compared to the tested results in safety side. The presented overall investigation may provide reference for the design and construction of such hybrid deck system.

• Coupled systems mechanics
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• 제7권5호
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• pp.555-581
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• 2018

The moment-resistant steel frames are frequently used as a load-bearing structure of buildings. Global response of a moment-resistant frame structure strongly depends on connections behavior, which can significantly influence the response and load-bearing capacity of a steel frame structure. The analysis of a steel frame with included joints behavior is the main focus of this work. In particular, we analyze the behavior of two connection types through experimental tests, and we propose numerical beam model capable of representing connection behavior. The six experimental tests, under monotonic and cyclic loading, are performed for two different types of structural connections: end plate connection with an extended plate and end plate connection. The proposed damage-plasticity model of Reissner beam is able to capture both hardening and softening response under monotonic and cyclic loading. This model has 18 constitutive parameters, whose identification requires an elaborate procedure, which we illustrate in this work. We also present appropriate loading program and arrangement of measuring equipment, which is crucial for successful identification of constitutive parameters. Finally, throughout several practical examples, we illustrate that the steel structure connections are very important for correct prediction of the global steel frame structure response.

• 한국압력기기공학회 논문집
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• 제12권1호
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• pp.11-16
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• 2016

Fuel assembly's mechanical characterization test facility (FAMeCT) in KAERI was constructed with upgraded functional features such as increased loading capacity, underwater vibration testing and severe earthquake simulation for extended fuel design guideline. This facility is designed and developed to provide out-pile fuel data for accident analysis model and fuel licensing. Functional tests of FAMeCT were performed to confirm functionality, structural integrity, and validity of newly-built fuel assembly mechanical test facility. Test program includes signal check of data acquisition system, load delivering capacity using real-sized fuel assemblies and a standard loading cylindrical rigid specimen. Fuel assembly's lateral bending test was carried out up to 30 mm of pull-out displacement. Limit case axial compression loading test up to 33 kN was performed to check structural integrity of UCPS (Upper Core Plate Simulator) support frame. Test results show that all test equipment and measurement system have acceptable range of alignment, signal to noise ratio, load carrying capacity limit without loss of integrity. This paper introduces newly constructed fuel assembly's mechanical test facility and summarizes results of functional test for the mechanical test equipment and data acquisition system.

• Structural Engineering and Mechanics
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• 제35권1호
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• pp.37-52
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• 2010

Special-shape arch bridge for self-balance (SBSSAB) in Zhongshan City is a kind of new fashioned spatial combined arch bridge composed of inclined steel arch ribs, curved steel box girder and inclined suspenders, and the mechanical behavior of the SBSSAB is particularly complicated. The SBSSAB is aesthetic in appearance, and design of the SBSSAB is artful and particular. In order to roundly investigate the mechanical behavior of the SBSSAB, 3-D finite element models for spatial member and shell were established to analyze the mechanical properties of the SBSSAB using ANSYS. Finite element analyses were conducted under several main loading cases, moreover deformation and strain values for control section of the SBSSAB under several main loading cases were proposed. To ensure the safety and rationality for optimal design of the SBSSAB and also to verify the reliability of its design and calculation theories, the 1/10 scale model tests were carried out. The measured results include the load checking calculation, lane loading and crowd load, and dead load. A good agreement is achieved between the experimental and analytical results. Both experimental and analytical results have shown that the SBSSAB is in the elastic state under the planned test loads, which indicates that the SBSSAB has an adequate load-capacity. The calibrated finite-element model that reflects the as-built conditions can be used as a baseline for health monitoring and future maintenance of the SBSSAB.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.575-586
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• 2008

The main objective of this paper is to develop an improved model for the analysis of liquefaction potential and to predict excess pore pressure (EPP) using the proposed model that can simulate behavior of saturated sand under earthquake loading conditions. The damage concept is adopted for the development of the proposed model. For the development of the model, a general formulation based on experimental results and damage potential using cumulative absolute velocity (CAV) is proposed for a more realistic description of dynamic responses of saturated sand. Undrained dynamic triaxial tests are conducted using earthquake loading conditions. Based on test results, the NCER-NCW function in terms of $w_d$ and CAV is developed. Procedure for the evaluation of EPP and determination of model parameters for the proposed model is presented as well. For the determination of initial liquefaction, the minimum curvature method using the NCS-NCW curve is proposed. It is observed that predicted initial liquefaction using the proposed method agrees well with measured initial liquefaction. From results of additional undrained dynamic triaxial tests, it is seen that predicted EPP generation using the proposed model agrees well with measured results for earthquake loading cases.

• 대한토목학회논문집
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• 제12권4_1호
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• pp.23-32
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• 1992

본 연구의 목적은 지진에 의한 강구조 부재의 소성피로손상 및 파괴에 크게 영향을 미치는 중요한 인자를 추출하여 그들간의 정량적 관계를 규명하는 것이다. 이를 위해, 앵글 강부재에 대하여 5~30 사이클 정도의 극저사이클 피로파괴실험을 실시하였다. 실험은 축방향 상대변위에 의해 제어된 반복 하중하에서 행하였으며, 앵글 시험체는 재하초기에 비탄성 전체좌굴 또는 국부좌굴이 발생하였다. 실험결과, 극저사이클 피로파괴하에서 강부재의 에너지 흡수능력은 재하이력과 파괴모우드에 따라 크게 변한다는 것을 알 수 있었고, 균열발생부에서 잔류 국소변형률의 최대치는 재하패턴 변형모우드 폭두께비에 관계없이 25~40% 정도였다.