• Wind and Structures
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• 제1권3호
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• pp.225-241
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• 1998

The high-rise supporting towers of long-span suspension and cable-stayed bridges commonly comprise a pair of slender prisms of roughly square cross-section with a center-to-centre spacing of from perhaps 2 to 6 widths and connected by one or more cross-ties. The tower columns may have a constant spacing as common for suspension bridges or the spacing may reduce towards the top of the tower. The present paper is concerned with the aerodynamics of such towers and describes an experimental investigation of the overall aerodynamic forces acting on a pair of square cylinders in two-dimensional flow. Wind tunnel pressure measurements were carried out in smooth flow and with a longitudinal intensity of turbulence 0.10. Different angles of attack were considered between $0^{\circ}$ and $90^{\circ}$, and separations between the two columns from twice to 13 times the side width of the column. The mean values of the overall forces proved to be related to the bias introduced in the flow by the interaction between the two cylinders; the overall rms forces are related to the level of coherence between the shedding-induced forces on the two cylinders and to their phase. Plots showing the variation of the force coefficients and Strouhal number as a function of the separation, together with the force coefficients spectra and lift cross-correlation functions are presented in the paper.

• 한국해양공학회지
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• 제15권1호
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• pp.98-103
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• 2001

This paper is conducted to compare the seismic design standard of a bridge column such as the Korean Bridge Design Standard(KBDS), EC 8, NZS 3101 and ATC 32. The KBDS adopted the seismic design requirements in 1992. The earthquake magnitude in Korea is compared with those in the west coast of the USA. It may be said that the current seismic design requirements of the KBDS provides design results, that are too conservative especially for transverse reinforcement details and amounts in reinforced concrete columns. This fact usually creates construction problems in concrete casting, due to congestion of transverse reinforcement. Furthermore, the effective stiffness; $I_{eff}$ depends on both the axial load P/$A_gF_{ck}$ and the longitudinal reinforcement ratio $A_{st}/A_g, so it is the conservative to use the effective stiffness I$_{eff}$ than the gross section stiffness Ig. Seismic design for the transverse reinforcement content of the concrete column was analyzed and considered to have an extreme-fiber compression strain, response modification factor, axial load and effective stiffness etc.c.

• 한국구조물진단유지관리공학회 논문집
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• 제24권6호
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• pp.59-66
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• 2020

축소모형 팔각형 기둥 실험체 2개를 제작하여 일정한 축력 하에서 반복 횡하중을 가력하는 실험을 수행하였다. 실험체는 중실단면과 중공단면이고 모든 실험체의 횡방향 나선철근 체적비는 0.00206의 값을 갖는다. 실험체들은 휨-전단 파괴거동을 보였다. 본 논문에서는 실험결과에 따른 파괴거동과 내진성능을 분석하였다. 실험결과, 중공 실험체는 초기강성, 초기 균열양상, 에너지 소산능력 등의 구조성능이 중실 실험체와 유사한 거동을 보였으나, 중공 실험체의 경우에는 3% 변위비 이후에 횡력, 극한변위, 에너지소산능력이 현저하게 감소되었다.

• 콘크리트학회논문집
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• 제20권2호
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• pp.193-202
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• 2008

현행 도로교설계기준의 내진설계기준은 완전연성 설계 개념을 채택함으로써, 과도하게 배근되는 횡구속철근으로 인하여 현장 시공에 어려움을 겪는 사례가 많이 있다. 이것은 한반도와 같은 중 약진직역에서 완전연성이 필요하지 않는 경우가 일반적임에도 불구하고 완전연성을 확보하기 위한 심부 구속철근량이 배근되기 때문이다. 이와 같은 문제점을 해결하기 위한 방안으로 한정연성 설계개념을 도입한 연성도 내진설계법이 제안된 바 있다. 연성도 내진설계법에서는 재료강도와 함께 소요연성도와 형상비를 변수로 하여 횡구속철근량을 결정하는 산정식을 사용하고 있다. 본 논문은 횡구속철근 산정식을 중심으로 연성도 내진설계법의 안전성을 검증함을 목적으로 한다. 국내 외에서 수행된 89개의 원형단면 기둥 실험 결과를 대상으로 변위연성도 안전율을 검토한 결과 1.11$\sim$3.98 사이의 값을 보였으며, 평균 변위연성도 안전율은 1.90으로 충분한 안전율을 보였다. 이 논문에서는 또한 연성도 내진설계법의 구체적인 설계절차도 소개하였으며, 횡구속철근의 설계에 고려되는 주요 변수들이 변위연성도 안전율에 주는 영향도 분석하였다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 추계 학술발표회 논문집
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• pp.141-146
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• 2002

In the present design concept, the nonlinear behavior of bridges is allowed under large earthquake. Therefore, demands for nonlinear analyses of bridges are increased more and more especially in the area of seismic assessment. It is, however, difficult to solve the problem how the nonlinearity of columns should be modelled. In this study, the fiber element Is adopted for model ins pier column. The element is a kind of structural elements like frame element, and it can model the distributed plasticity of plastic hinge. A 3 span continuos bridge is taken for seismic analysis. First, the nonlinear static analysis the column at fixed support are performed so that the characteristics of column is investigated. Second, the nonlinear dynamic analyses of the full bridge model is performed, considering 3 directional earthquake excitations.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.931-936
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• 2003

Lap splices were located in the plastic hinge region of most bridge piers that were constructed before the adoption of the seismic design provision of Korea Highway Design Specification on 1992. Lap splicing is also permitted if hoops or spiral reinforcement are provided over the lap length in the current seismic design provision. But sudden brittle failure of lap splices may occur under inelastic cyclic loading. The purpose of this study is the analytical prediction of nonlinear hysteretic behavior and ductility capacity of reinforced concrete bridge piers with lap splices under cyclic loading. For this purpose, a nonlinear analysis program, RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology) is used. Lap spliced bar element is developed to predict behaviors of lap spliced bar. Maximum bar stress and slip of lap spliced bar is considered.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.250-257
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• 2002

Pseudo dynamic test is an on-line computer control method to achieve the realism of shaking table test with the economy and versatility of the conventional quasi-static approach Pseudo dynamic tests of six full-size RC bridge piers have been carried out to investigate their seismic performance. For the purpose of precise evaluation, the experimental investigation was conducted to study the seismic performance of the real size specimen, which is constructed for highway bridge piers in Korean peninsula. Since it is believed that Korea belongs to the moderate seismicity region, five test specimens were designed in accordance with limited ductility design concept. Another one test specimen was nonseismically designed according to a conventional code. Important test parameters were transverse reinforcement and lap splicing. Lap splicing was frequently used in the plastic hinge region of many bridge columns. Furthermore, the seismic design code is not present about lap splice in Korean Roadway Bridge Design Code. The results show that specimens designed according to the limited ductility design concept exhibit higher seismic resistance. Specimens with longitudinal steel lap splice in the plastic hinge region appeared to significantly fail at low ductility level.

• 한국지진공학회논문집
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• 제18권1호
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• pp.9-18
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• 2014

The purpose of this study is to investigate the seismic behavior of hollow reinforced concrete bridge column systems with reinforcement details for material quantity reduction and to provide the details and reference data. Five hollow reinforced concrete bridge columns were tested under a constant axial load and a cyclically reversed horizontal load. The accuracy and objectivity of the assessment process can be enhanced by using a sophisticated nonlinear finite element analysis program. The adopted numerical method gives a realistic prediction of seismic performance throughout the loading cycles for several the investigated test specimens. This study documents the testing of hollow reinforced concrete bridge column systems with reinforcement details for material quantity reduction and presents conclusions based on the experimental and analytical findings.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.885-890
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• 2002

Pseudo dynamic test is an on-line computer control method to achieve the realism of shaking table test with the economy and versatility of the conventional quasi-static approach. Pseudo dynamic tests of four full-size RC bridge piers have been carried out to investigate their seismic performance. For the purpose of precise evaluation, the experimental investigation was conducted to study the seismic performance of the real size specimen, which is constructed for highway bridge piers in Korean peninsula. Since it is believed that Korea belongs to the moderate seismicity region, three test specimens were designed in accordance with limited ductility design concept. Another one test specimen was nonseismically designed according to a conventional code. Important test parameters were transverse reinforcement and lap splicing. Lap splicing was frequently used in the plastic hinge region of many bridge columns. Furthermore, the seismic design code is not present about lap splice in Korean Roadway Bridge Design Code. The results show that specimens designed according to the limited ductility design concept exhibit higher seismic resistance. Specimens with longitudinal steel lap splice in the plastic hinge region appeared to significantly fail at low ductility level.

• Structural Engineering and Mechanics
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• 제65권6호
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• pp.771-784
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• 2018

This study aims to investigate the stochastic response of isolated and non-isolated highway bridges subjected to spatially varying earthquake ground motion model. This model includes wave passage, incoherence and site response effects. The wave passage effect is examined by using various wave velocities. The incoherency effect is investigated by considering the Harichandran and Vanmarcke coherency model. The site response effect is considered by selecting homogeneous firm, medium and soft soil types where the bridge supports are constructed. The ground motion is described by power spectral density function and applied to each support point. Triple concave friction pendulum (TCFP) bearing which is more effective than other seismic isolation systems is used for seismic isolation. To implement seismic isolation procedure, TCFP bearing devices are placed at each of the support points of the deck. In the analysis, the bridge selected is a five-span featuring cast-in-place concrete box girder superstructure supported on reinforced concrete columns. Foundation supported highway bridge is regarded as three regions and compared its different situation in the stochastic analysis. The stochastic analyses results show that spatially varying ground motion has important effects on the stochastic response of the isolated and non-isolated bridges as long span structures.