• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.710-713
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• 2011

본 논문에서는 교량의 주부재에 교량용 고성능강을 적용하여 설계해 본 후, 이러한 적용이 교량의 진동사용성에 어떠한 영향을 미치는지 그 영향을 분석해 보고자 한다. 최근들어 교량상의 구조적인 결함이 없더라도 진동에 의해 교량을 통행하는 운전자나 보행자에게 불안감을 주는 경우가 빈번히 발생하기 때문에 진동사용성이란 문제는 보다 부각되고 있다. 특히 고성능강이 개발되고 이를 교량에 적용하게 되면 허용응력의 증가로 이어져 거더의 형고감소를 가능하게 한다. 그러나 이러한 형고의 감소는 교량의 휨강성을 저하시켜 사용성의 악화를 초래할 것이란 예측이 있었다. 따라서 본 연구는 차량-교량의 상호작용에 의해 발생하는 진동영향의 분석을 위해 유한요소해석 프로그램인 Abaqus 6.10을 이용해 수치해석을 수행하였고 이때의 진동영향을 평가했다. 차량-교량 상호작용의 해석을 위해 ASSHTO 기준의 HS 20-44 차량을 해석 대상교량 위로 주행하도록 하였다. 해석대상교량은 인장강도가 각각 600MPa와 800MPa인 교량용 고성능강재(HSB, High-Performance Steel for Bridge)를 적용하여 주거더를 설계한 강플레이트 거더교를 대상으로 삼았다. 차량이 교량을 통과하면서 발생하는 교량의 경간 중앙부에서 발생하는 수직진동의 시간이력을 분석하여 진동평가의 기준으로 삼았다. 해석결과 HSB600과 HSB800으로 각각 설계된 교량은 가속도이력에서는 큰 차이가 없었으나 변위이력에서는 HSB800적용 교량이 진동사용성 측면에서 매우 불리한 거동을 보였다. 따라서 고성능강 적용에 따른 교량의 진동사용성을 평가하기 위해서는 변위를 기준으로한 평가가 이루어져야하며, 변위의 진동을 제어하기 위한 방안이 모색되어야 할 것으로 판단된다.

• Journal of Korean Society of Steel Construction
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• v.26 no.4
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• pp.299-309
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• 2014

HSA800 is a new high strength steel (HSS) plate for building structures developed by POSCO and RIST in 2011. It has upper and lower bounds for yield ($F_y$) and tensile ($F_u$) strength as of 650-770MPa and 800-950MPa, respectively, with yield ratio ($F_y/F_u$) limit as of 0.85 which make steel quality more reliable and enhance the seismic resistance of structures. As made by TMCP, it has a good weldability without increasing carbon percentage. The objective of this study is to provide alternative design of mega-structural members of the Lotte World Tower (555m, 123 story), a first super-tall building in Korea, using HSS considering structural safety, constructability, and cost-effectiveness. Steel outrigger trusses, belt-trusses and steel exterior columns were selected and analyzed to evaluate the structural performance between original and alternative designs using HSS. The results show that HSS can be applied to the members which do not affect lateral stiffness of a building and, in this study, approximately 1100tons of steel were saved. It implies that HSS can save overall construction costs - manufacturing, delivery, and erection costs - by reducing mega structural member size. HSA800 was very first applied to the Lotte World Tower based on the results of this study.

• Journal of Korean Society of Steel Construction
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• v.23 no.3
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• pp.385-395
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• 2011

The flexural strength of composite HSB hybrid I-girders under positive moment is investigated by the moment-curvature analysis method to evaluate the applicability of the current AASHTO LRFD design specification to such girders. The hybrid girders are assumed to have the top flange and the web fabricated from HSB600 steel and the bottom flange made of HSB800 steel. More than 6,200-composite I-girder sections that satisfy the section proportion limits of AASHTOL RFD specifications are generatedby the random sampling technique to consider a statistically meaningful wide range of section properties. The flexural capacities of the sections are calculated by the nonlinear moment-curvature analysis in which the HSB600 and HSB800 steels are modeled as an elastoplastic, strain-hardening material and the concrete as CEB-FIP model. The effects of ductility ratio and compressive strength of concrete slab on the flexural strength of composite hybrid girders make of HSB steels are analyzed. Numerical results indicated that the current AASHTO-LRFD equation can be used to calculate the flexural strength of composite hybrid girders fabricated from HSB steel.

• Journal of Korean Society of Steel Construction
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• v.20 no.6
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• pp.783-792
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• 2008

While the recent high demand for mega-tall buildings has led to the development of high-performance and high-strength steels, the requirements for architectural-structure-performance steel have been raised as engineers recognize the potential damage that an earthquake can wreak on a tall building. A 600MPa-class steel has emerged to meet such need, and many studies are currently exploring its practical applications on civil engineering works and mega-tall buildings. The available data on the horizontal-force behaviors of structures built with such new steel, however, are still insufficient. There is an urgent need to look into its design data, especially its toughness, and to compare the plastic strain ratios of column-to-beam connections using high-strength steel and regular steel. One of the first studies on the behavior of a column-to-beam connection using 600MPa-class steel (SM570 TMC), this thesis analyzes such steel's structural performance by conducting a structural test on seismic resistance on a full-scale column-to-beam welded connection with non-scallop and recommended-scallop details. Compared with the previous studies on SM490, this thesis evaluates the weldability of SM570 TMC and presents the latter's seismic design data for use in testing its practical application.

• Journal of Korean Society of Steel Construction
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• v.22 no.4
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• pp.377-388
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• 2010

The flexural behavior of composite HSB600 and HSB800 I-girders under a positive moment was investigated using the material non-linear moment-curvature analysis method. Three representative composite sections with different ductility properties were selected as the baseline sections in this study. Using these baseline sections, the moment-curvature program was verified by comparing the flexural strength and the moment-curvature curve obtained from the program with those obtained using the non-linear FE analysis of ABAQUS. In the FE analysis, the composite girders were modeled three-dimensionally with flanges, the web, and the concrete slab as thin shell elements, and initial imperfections and residual stresses were imposed on the FE model. In the moment-curvature and FE analyses, the 28-day compressive strength of the concrete slab was assumed to be 30-50 MPa, and the HSB600 and HSB800 steels were modeled as elasto-plastic strain-hardening materials, with the concrete as the CEB-FIP model. The effects of the ductility ratio of the composite girder, the type of steel, the compressive strength of the concrete deck, and the location of the plastic neutral axis on the flexural characteristics were analyzed.

• Composites Research
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• v.24 no.5
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• pp.29-33
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• 2011

The application of high performance materials for the deck can represent a fair alternative to reduce the weight of the deck and improve the econimic efficiency of the bridge even if high performance materials are costly. In UHPC(Ultra High Performance Concrete) bridges, it is necessary to verify that exiting headed stud can be used to transfer longitudinal shear forces across the steel-concrete interface. In this paper, the push-out tests are performed to analisys the composite behavior between UHPC bridge deck and steel girder. The ultimate strength of test specimens is proportional to the diameter of headed studs in push-out test for static loading. Test results show that the shear strength of headed stud is improved for the case of normal concrete bridge decks.

• Journal of Korean Society of Steel Construction
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• v.20 no.6
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• pp.773-781
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• 2008

As buildings are becoming taller and longer-spanned, the requirements of high-strength and reliable steels are becoming increasingly stringent. Structural steels, however, acquire significantly different mechanical properties when their strength becomes higher. In this study, the mechanical properties, welding characteristics, and conformities of the 600MPa-grade high-strength steel were tested. The 600MPa-grade steel plates exhibited stable criterion strengthvalues and showed low carbon equivalents (${\mathcal{Ceq}}$) and composition (${\mathcal{Pcm}}$) as well as excellent welding hardness. In the tensile strength test, all the specimens were found to have strengths of over 600MPa. In the Sharphy impact test, the impact-absorbed energy of the V-notch specimens was shown to be 47J at the KS limit. Moreover, the maximum hardness of the specimens in the weld-heat-affected zone at a normal temperature was the same as that before welding. Their weld metal properties, however, were found not to be as good as those of high-strength steel. As such, the details of high-strength steel must be determined.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2002.05a
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• pp.401-409
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• 2002

인터넷과 같은 대량의 정보에 대응할 수 있는 고성능 정보검색시스템을 구축하기 위해서는 지금까지 고가의 중대형 컴퓨터를 주로 활용하여 왔으나, 최근 가격대 성능비가 높은 PC 클러스터 시스템을 활용하는 방안이 경제적인 대안으로 떠오르고 있다. PC 클러스터 상에서의 병렬정보검색시스템을 효율적으로 운영하기 위해서는 사용자가 입력한 질의를 처리하는데 요구되는 개별 PC의 디스크 I/O 및 검색관련 연산을 모든 PC에 가능한 균등하게 분배할 필요가 있다. 본 논문에서는 같은 질의에 동시에 등장할 가능성이 높은 색인어들끼리 군집 화하고 생성된 군집을 활용하여 색인어들을 각 PC에 분산저장함으로써 보다 높은 수준의 병렬화를 달성할 수 있는 방안을 제시한다. 대용량 말뭉치를 활용한 실험결과 본 논문에서 제시하는 분산저장기법이 충분한 효율성을 가지고 있음을 확인하였다.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2003.05a
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• pp.457-466
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• 2003

인터넷과 같은 대량의 정보에 대응할 수 있는 고성능 정보검색시스템을 구축하기 위해서 지금까지는 고가의 중대형 컴퓨터를 주로 활용하여 왔으나, 최근 가격대 성능비가 높은 PC 클러스터 시스템을 활용하는 방안이 경제적인 대안으로 떠오르고 있다. PC 클러스터 시스템에서는 전체 작업을 개별 노드 즉 PC에 가능한 균등하게 분배함으로써 성능을 극대화 하고자 하는데, 하나 또는 그 이상의 노드에 문제가 발생하는 경우 전체시스템의 성능이 매우 저하되거나 정상적인 서비스를 제공하기가 어려워진다. 이러한 상황에서 고장 포용성의 달성은 1년 365일 지속적으로 운영되어야 하는 많은 응용분야에서 반드시 해결해야 하는 문제이다. 본 논문에서는 PC 클러스터를 활용한 병렬정보검색시스템에서 고장 포용성을 극대화하기 위하여 각 노드의 색인어 역파일을 이웃 노드에 효율적으로 중복하여 저장하는 방안과 이를 활용한 효과적인 병렬정보검색 방법을 제안한다. 대규모 말뭉치를 활용한 실험결과 본 논문에서 제시하는 고장 포용성 향상을 위한 색인어 역파일 중복 저장방안이 충분한 효율성과 실용성이 있음을 확인하였다.

• Journal of Korean Society of Steel Construction
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• v.28 no.6
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• pp.403-414
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• 2016

Recently according to the decreasing of steel price and increasing of labor cost the various studies of steel structure and composite structure are proceeding. This study developed the new shape of high depth hybid forming composite beam and performed the bending test to evaluate the bending performance by creating 10 specimens. Bending test result showed that capacity of the beam was increased stably. The ratio of the nominal load to the maximum load($P_u/P_n$) is 1.19 and the deformation capacity(${\delta}_{0.8P_u}/{\delta}_y$) is 3.9~4.5. Also, it is possible to apply the existing evaluation equation(KBC 2009) of composite beam.