• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.125-128
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• 2006

Many research have been carried out concerned with the flexural performance of FRP composite in a various ways. Most of them, however, have used a small-scale specimen, so haven't been fully verified by full-scale model test. In this study, a full-scale RC beam model test for flexural strengthening with CFRP composites has been performed in order to verify test results obtained through a series of small-scale model test with respect to FRP stiffness affecting strengthening performance in the previous studies. A total of 4 specimens have been manufactured including control beam. The specimens strengthened with CFRP composites consist of 3 different CFRP stiffness with 2 types of CFRP composite. Consequently, the purpose of this study is to estimate influence of the size effect of specimens and FRP stiffness on the flexural performance. As a result, the effective strain of FRP composite is inversely proportional to FRP stiffness and ensures the same performance with small-scale model test.

• 한국전산구조공학회논문집
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• 제23권2호
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• pp.175-182
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• 2010

본 연구에서는 복합소재 교량용 방호울타리를 개발하여 컴퓨터 시뮬레이션을 통해 강재 교량용 방호울타리와 복합소재교량용 방호울타리의 성능을 비교하였다. 구조적 강도 성능 측면에서, 복합소재 교량용 방호울타리의 경우 교량용 방호울타리의 변형이 17%로 감소하여 강재 교량용 방호울타리 보다 강도 성능이 우수하였다. 탑승자 보호 성능 측면에서, 복합소재 교량용 방호울타리는 THIV 47.1%, PHD 49.0%로 감소하여 강재 교량용 방호울타리 보다 탑승자 보호성능이 우수하였다. 충돌 후 차량의 거동 측면에서, 복합소재 교량용 방호울타리는 이탈속도가 증가하고 이탈각도가 감소하여 강재 교량용방호울타리 보다 충돌 후 차량의 거동이 우수하였다. 교량용 방호울타리의 비산 측면에서, 강재 및 복합소재 교량용 방호울타리는 비산이 발생하지 않았다.

• Steel and Composite Structures
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• 제19권4호
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• pp.789-809
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• 2015

This paper presents experimental and numerical studies into the structural behavior of a high performance corbel type composite connection adopted in Raffles City of Hangzhou, China. Physical tests under both monotonic and quasi-static cyclic loads were conducted to investigate the load carrying capacities and deformation characteristics of this new type of composite connection. A variety of structural responses are examined in detail, including load-deformation characteristics, the development of sectional direct and shear strains, and the history of cumulative plastic deformation and energy. A three-dimensional finite element model built up with solid elements was also proposed for the verification against test results. The studies demonstrate the high rigidity, strength and rotation capacities of the corbel type composite connections, and give detailed structural understanding for engineering design and practice. Structural engineers are encouraged to adopt the proposed corbel type composite connections in mega high-rise buildings to achieve an economical and buildable and architectural friendly engineering solution.

• Steel and Composite Structures
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• 제8권1호
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• pp.35-52
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• 2008

The paper investigates the seismic performance of a Partially-Restrained (PR) steel-concrete composite frame using the probabilistic approach. The analysed frame was tested at the ELSA laboratory of the Joint Research Centre of Ispra (Italy), while the representative beam-to-column composite connections were tested at the Universities of Pisa, Milan and Trento (Italy). The component modelling of both interior and exterior composite joints is described first, including the experimental-numerical validation. The Latin Hypercube method has been used to draw the probabilistic distribution curves of joints, and then the whole PR composite frame has been analysed. Pushover and incremental dynamic analyses have been carried out using the non-linear FE code SAP2000 version 9.1. The fragility and performance curves of the PR composite frame have been determined for four damage limit states.

• Structural Engineering and Mechanics
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• 제55권5호
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• pp.931-951
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• 2015

To improve the durability and service life of reinforced concrete column such as bridge piers, an advanced composite column made of Ultra High Performance Cementitious Composites (UHPCC) permanent form is proposed. Based on elasticity plasticity theory, axial compression behavior of the composite column was studied theoretically. The first circumferential cracking load and ultimate limit loading capacity are derived for the composite column. Short composite column compression tests and numerical simulations using FEM method were carried out to justify the theoretical formula. The effects of UHPCC tube thickness on the axial compression behavior were studied. Using the established theoretical model and numerical simulation, the large dimension composite columns are calculated and analyzed with different UHPCC tube thickness. These studies may provide a reference for advanced composite column design and application.

• Steel and Composite Structures
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• 제30권6호
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• pp.577-589
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• 2019

In this study, on-site testing was carried out to investigate the vibration performance of a composite steel-bar truss slab with steel girder system. Ambient vibration was performed to capture the primary vibration parameters (natural frequencies, damping ratios, and mode shapes). The composite floor possesses low frequency (< 10 Hz) and damping (< 2%). Based on experimental, theoretical, and numerical analyses on natural frequencies and mode shapes, the boundary condition of SCSC (i.e., two opposite edges simply-supported and the other two edges clamped) is deemed more reasonable for the composite floor. Walking excitations by one person (single excitation), two persons (dual excitation), and three persons (triple excitation) were considered to evaluate the vibration serviceability of the composite floor. The measured acceleration results show a satisfactory vibration perceptibility. For design convenience and safety, a crest factor ${\beta}_{rp}$ describing the ratio of peak acceleration to root-mean-square acceleration induced from the walking excitations is proposed. The comparisons of the modal parameters determined by ambient vibration and walking tests reveal the interaction effect between the human excitation and the composite floor.

• 한국전산구조공학회논문집
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• 제24권5호
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• pp.499-506
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• 2011

본 연구에서는 컴퓨터 시뮬레이션을 통해 복합소재 교량용 방호울타리의 성능을 분석하였다. 복합소재 방호울타리는 SB4등급을 선정하였다. 복합소재의 적층을 고려하기 위해 LS-DYNA에서 제공하는 재료모델 MAT58을 사용하였다. 복합소재는 섬유와 수지의 종류 및 섬유의 방향에 따라 성능이 상이하다. 수지는 폴리우레탄, 섬유는 유리섬유를 사용하였다. 본 논문에서는 섬유의 방향성이 다른 3가지 적층 설계안에 대해서 충돌 시뮬레이션을 수행하여 성능을 비교 평가하였다. 실차충돌 실무 업무편람에 따라 구조적 강도성능, 탑승자 보호성능, 충돌 후 차량의 거동, 가드레일의 비산에 대한 성능 평가를 실시하였다. 그 결과 적층 설계의 횡 방향 섬유의 양이 많아질수록 충돌 시뮬레이션에서 더 좋은 성능을 나타내었다.

• Steel and Composite Structures
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• 제38권1호
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• pp.103-120
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• 2021

This research examines the eccentric compression performance of composite columns composed of recycled aggregate concrete (RAC)-filled square steel tube and profile steel. A total of 17 specimens on the composite columns with different recycled coarse aggregate (RCA) replacement percentage, RAC strength, width to thickness ratio of square steel tube, profile steel ratio, eccentricity and slenderness ratio were subjected to eccentric compression tests. The failure process and characteristic of specimens under eccentric compression loading were observed in detail. The load-lateral deflection curves, load-train curves and strain distribution on the cross section of the composite columns were also obtained and described on the basis of test data. Results corroborate that the failure characteristics and modes of the specimens with different design parameters were basically similar under eccentric compression loads. The compression side of square steel tube yields first, followed by the compression side of profile steel. Finally, the RAC in the columns was crushed and the apparent local bulging of square steel tube was also observed, which meant that the composite column was damaged and failed. The composite columns under eccentric compression loading suffered from typical bending failure. Moreover, the eccentric bearing capacity and deformation of the specimens decreased as the RCA replacement percentage and width to thickness ratio of square steel tube increased, respectively. Slenderness ratio and eccentricity had a significantly adverse effect on the eccentric compression performance of composite columns. But overall, the composite columns generally had high-bearing capacity and good deformation. Meanwhile, the mechanism of the composite columns under eccentric compression loads was also analysed in detail, and the calculation formulas on the eccentric compression capacity of composite columns were proposed via the limit equilibrium analysis method. The calculation results of the eccentric compression capacity of columns are consistent with the test results, which verify the validity of the formulas, and the conclusions can serve as references for the engineering application of this kind of composite columns.

• Journal of Electrochemical Science and Technology
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• 제2권1호
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• pp.32-38
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• 2011

The composite barium strontium cobalt ferrite (BSCF) cathodes were investigated in the intermediate temperature range of solid oxide fuel cells (SOFCs). The characteristics and electrochemical performances of composited BSCF/samarium doped ceria (SDC); BSCF/gadolinium doped ceria (GDC); and BSCF/SDC/GDC were compared to single BSCF cathode. The BSCF used in this study were synthesized using glycine nitrate process and mechanically mixing was used to fabricate a composite cathode. Using a composite form, the thermal expansion coefficient (TEC) could be reduced and BSCF/SDC/GDC exhibited the lowest TEC value at $18.95{\times}10^{-6}K^{-1}$. The electrochemical performance from half cells and single cells exhibited nearly the same trend. All the composite cathodes gave higher electrochemical performance than the single BSCF cathode (0.22 $Wcm^{-2}$); however, when two kinds of electrolyte were used (BSCF/SDC/GDC, 0.36$Wcm^{-2}$), the electrochemical performance was lower than when the BSCF/SDC (0.45 $Wcm^{-2}$) or BSCF/GDC (0.45 $Wcm^{-2}$) was applied as cathode ($650^{\circ}C$, 97%$H_2$/3%$H_2O$ to the anode and ambient air to the cathode).

• Steel and Composite Structures
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• 제18권5호
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• pp.1279-1290
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• 2015

The main role of studs, which act as connectors of the steel-concrete composite structures, is to ensure that the steel and the concrete work together as a whole. The studs in steel-concrete composite structures bear the shearing force in the majority of cases, but in certain locations, such as the mid-span of a simply supported composite beam, the studs bear axial uplift force. The previous studies mainly focused on the shearing performance of the stud by some experimental and theoretical effort. However, rare studies involved the uplift performance of studs. In this paper, the single stud uplift test on 10 composite specimens was performed. Meanwhile, based on the test, numerical analysis was introduced to simulate the concrete damage process due to the stud uplifted from concrete. The static ultimate bearing capacity, under which the stud connector was pulled out from the damaged reinforced concrete, is much larger than the cyclic ultimate bearing capacity, under which the weld joint between stud and steel plate fractured. According to the fatigue test results of 7 specimens, the fatigue S-N curve of the construction detail after minus 2 times standard deviation is $logN=24.011-9.171\;log{\Delta}{\sigma}$, the fatigue strength corresponding to $2{\times}10^6$ cycles is 85.33 MPa.