• Steel and Composite Structures
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• 제35권1호
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• pp.13-27
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• 2020

To investigate the stress-strain relation of PVC-FRP Confined Concrete (PFCC) column with RC ring beam joint subjected to eccentric compression, the experiment of 13 joint specimens, which were designed with principle of "strong joint and weak column", were presented. Several variable parameters, such as reinforcement ratio, width and height of ring beam, FRP strips spacing and eccentricity, were considered. The specimens were eventually damaged by the crushing of concrete, the fracture of PVC tube and several FRP strips. With the FRP strips spacing or eccentricity increased, the ultimate carrying capacity of specimens declined. The strain of FRP strips and axial strain of PVC tube decreased as FRP strips spacing decreased. The decrease of eccentricity would slow down the development of strain of FRP strips and axial strain of PVC tube. The slope of stress-strain curve of PFCC column decreased as FRP strips spacing or eccentricity increased. The ultimate strain of PFCC column reduced as FRP strips spacing increased, while the effect of eccentricity on the ultimate strain of PFCC was not distinct. Considering the influence of eccentricity on the stress-strain relation, a modified stress-strain model for conveniently predicting the weak PFCC column and strong RC ring beam joint under eccentric compression was proposed and it was in good agreement with the experimental data.

• Steel and Composite Structures
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• 제47권1호
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• pp.19-36
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• 2023

An experimental study of eleven PVC-FRP Confined Concrete (PFCC) column-Reinforced Concrete (RC) beam joints reinforced with Core Steel Tube (CST) under axial compression is carried out. All specimens are designed in accordance with the principle of "weak column and strong joint". The influences of FRP strips spacing, length and steel ratio of CST, height and stirrup ratio of joint on mechanical behavior are investigated. As the design anticipated, all specimens are destroyed by column failure. The failure mode of PFCC column-RC beam joint reinforced with CST is the yielding of longitudinal steel bars, CST and stirrups of column as well as the fracture of FRP strips and PVC tube. The ultimate bearing capacity decreases as FRP strips spacing or joint height increases. The effects of other three studied parameters on ultimate bearing capacity are not obvious. The strain development rules of longitudinal steel bars, PVC tube, FRP strips, column stirrups and CST are revealed. The effects of various studied parameters on stiffness are also examined. Additionally, an influence coefficient of joint height is introduced based on the regression analysis of test data, a theoretical formula for predicting bearing capacity is proposed and it agrees well with test data.

• Structural Engineering and Mechanics
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• 제77권1호
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• pp.75-87
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• 2021

The present study pertains to the introduction of two new types of grip adaptor for universal testing machines, namely Polyvinyl Chloride (PVC) and Polyoxymethylene (POM) grip adaptors, and their application to tension testing of FRP bars with different fiber and surface finish types. The tabs are connected to the FRP bar sample with the help of mechanical anchors, i.e. bolts. These new adaptors offer vital superiorities over the existing end tab designs (anchors with filling material or mechanical anchorage), including the reduction in the time and labor for production, reusability and the mild nature, i.e. low hardness of the tab material, which retards and even prevents peeling and crushing in the gripping regions of an FRP sample. The methods were successfully applied to FRP bars with different types of fiber (CFRP, GFRP and BFRP) and different types of surface texture (ribbed, wrapped, sand-coated and wound). The test results indicated that the both types of end caps prevented slip of the bar, crushing and peeling in the gripping zone. The mechanical properties from the material tests with the new caps were in perfect agreement with the ones from the material tests with steel tubular caps.

• 한국화재소방학회논문지
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• 제19권1호
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• pp.51-58
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• 2005

본 연구는 새로 개발된 난연도료를 바탕재(FRP PVC, AL, 스테인레스 스틸)에 도장한 실험체에 대하여 난연성. 화염전파. 산소지수. 가연성, 연기밀도, 독성지수를 평가하였다 연구결과 실험체(AL, 스테인레스 스틸)의 난연1급실험은 적합하였으며, 실험체(FRP, AL, 스테인레스 스틸)의 화염전파실험에서 착화되지 않았고, 실험체 모두의 산소지수는 약 $50\%$, 가연성실험은 V-0급으로 나타났다. 또한 연기밀도 챔버를 이용한 Flaming mode에서 최대연기밀도는 43-338 및 덕성지수는 0.57-1.12인 것으로 나타났다.

• Structural Engineering and Mechanics
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• 제77권2호
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• pp.179-196
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• 2021

Experimental investigations on the seismic behaviors of the PVC-FRP Confined Reinforced Concrete (PFCRC) columns under low cyclic loading are carried out and two variable parameters including CFRP strips spacing and axial compression ratio are considered. The PFCRC column finally fails by bending and is characterized by the crushing of concrete and yielding of the longitudinal reinforcement, and the column with a high axial compression ratio is also accompanied by the cracking of the PVC tube and the fracture of CFRP strips. The hysteretic curves and skeleton curves of the columns are obtained from the experimental data. With the increase of axial compression ratio, the stiffness degradation rate accelerates and the ductility decreases. With the decrease of CFRP strips spacing, the unloading sections of the skeleton curves become steep and the ductility reduces significantly. On the basis of fiber model method, a numerical analysis approach for predicting the skeleton curves of the PFCRC columns is developed. Additionally, a simplified skeleton curve including the elastic stage, strengthening stage and unloading stage is suggested depending on the geometric drawing method. Moreover, the loading and unloading rules of the PFCRC columns are revealed by analyzing the features of the skeleton curves. The quantitative expressions that are used to predict the unloading stiffness of the specimens in each stage are proposed. Eventually, an analytical model for the PFCRC columns under low cyclic loading is established and it agrees well with test data.

• 한국전산구조공학회논문집
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• 제23권6호
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• pp.715-726
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• 2010

In this paper, a comparative study of metallic and non-metallic stiffened plates under a lateral pressure load is performed using conventional statistically determinate and SQP(Sequential Quadratic Programming) optimisation approaches. Initially, a metallic flat-bar stiffened plate is exemplified from the superstructure of a marine vessel and, subsequently, its structural topology is varied as hat-section stiffened FRP(Fibre Reinforced Plastics) single skin plates and monocoque FRP sandwich plates having a PVC foam core. These proposed structural alternatives are analysed using elastic closed-form solutions and SQP optimisation method under stress and deflection limits obtained from practice to calculate and optimise geometry dimensions and weights. Results obtained from the comparative study provide useful information for marine designers especially at the preliminary design stage where various building materials and structural configurations are dealt with.

• Steel and Composite Structures
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• 제47권6호
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• pp.781-794
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• 2023

In order to directly apply seawater and sea sand in construction without desalination, a type of square concrete-filled steel tube (CFST) encased with prefabricated seawater sea-sand concrete filled Polyvinyl Chloride (PVC)/Glass Fiber Reinforced Polymer (GFRP) tube column was proposed. Twenty short columns were tested under uniaxial loads, and the test parameters included inner tube types, seawater sea-sand concrete replacement ratios, concrete strength, the wrapping area of Carbon Fiber Reinforced Polymer (CFRP) strips and the thickness of GFRP tube. The effects of the parameters on failure modes, loading capacity, ductility and strain responses were discussed. All the tested specimens failed with serious buckling of the steel tubes and fracture of the inner tubes. The specimens had good residual bearing capacity corresponding to 64% to 88.9% of the peak capacity. The inner GFRP tubes and PVC tubes wrapped by CFRP strips provided stronger confinement to the core concrete, and were good choices for the proposed columns. Moreover, an analytical model for the composite column with different inner tube types was proposed.

• 한국화재소방학회논문지
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• 제33권1호
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• pp.69-75
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• 2019

본 연구에서는 5종의 섬유강화플라스틱(Fiber Reinforced Plastic, FRP), 폴리스티렌(Polystylene, PS), 폴리카보네이트(Polycarbonate, PC), 폴리프로필렌(Polypropylene, PP), 폴리염화비닐(Polyvinyl chloride, PVC) 판을 콘칼로리미터(Cone calorimeter, ISO 5660)를 이용하여 연소성을 시험하였다. 그 결과 PVC판은 최대열방출률($HRR_{peak}$)이 $44.65kW/m^2$, 최대평균열방사율(MARHE)이 $30.97kW/m^2$로 가장 낮게 나타났고, PS판은 $HRR_{peak}$은 $773.44kW/m^2$, MARHE는 $399.14kW/m^2$으로 가장 높게 나타났다. 일산화탄소의 평균($CO_{mean}$) 발생량은 PC판과 PS판이 최대 3.88배로 가장 많이 발생하였고, 반대로 이산화탄소($CO_{2mean}$)의 평균 발생량은 PS판과 PP판이 최대 4.88배로 가장 많이 발생하였다. 또 PS판은 다른 플라스틱보다 연기성능지수(SPI)가 74.81%~95.99% 감소하였고, 연기성장지수(SGI)는 76%~300%, 연기강도(SI)는 917.73%~9607.57% 증가하여 연기위험성이 높다는 것을 알 수 있었다. 따라서 PS판은 열적 측면에서나 연기 측면 모두 연기로 인한 인명피해의 위험성이 가장 높았음을 알았다.

• 한국방재학회 논문집
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• 제5권4호
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• pp.79-84
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• 2005

건축물, 운송수단에 많이 사용되는 고분자재료는 화재에 노출되면 다량의 열 및 연소가스를 발생시켜 피해를 야기시키는데 특히 유독성 연소가스는 인명피해의 주된 원인이 된다. 본 연구에서는 화재시 발생되는 다양한 종류의 연소가스를 동시에 연속적으로 분석할 수 있는 새로운 분석방법인 FTIR(Fourier Transform Infrared) 분석방법을 이용하여 ASTM E 1678 실험장치에서 발생시킨 PVC, FRP, SMC 및 Ureathane foam 4종의 고분자재료 연소가스를 분석하였고, 분석된 연소가스 데이터를 NIST에서 개발한 FED 독성 모델에 적용하여 연소가스 유해성을 정량적으로 제시하였다. 또한 현재 우리나라에서 사용되고 있는 마우스를 사용한 KS F 2271 가스유해성 실험결과와 비교분석을 하였으며, FTIR 연소가스 분석방법을 이용하면 동물을 사용하지 않고서도 연소가스 유해성을 정량적이고 정확하게 평가할 수 있음을 알 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전기설비전문위원
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• pp.58-60
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• 2008

발전소에서 만들어진 전력을 소비자까지 수송하는 송변전변 및 배전설비를 주 대상으로 하는 전력계통 설비의 운영에는 전력의 수송과 이를 위해 설치되는 각종 기자재로부터 인체 및 재산의 안전을 확보하기 위해 많은 종류의 절연재를 사용하고 있다. 지금까지 전력분야에서 사용되어 온 절연재는 자기재(porcelain)가 주종을 이루어 왔으나 재료기술의 발달과 함께 폴리머 절연재료들이 속속 개발되면서 자기재에 비해 가격 및 시공성 등에서 이점이 많은 폴리머 절연재가 자기재를 대체하고 있다. 그러나 폴리머 절연재료는 기들의 재질 및 사용 환경 등에 따라 일정 수명을 가지는 것으로 나타나 수명종기에 이르면 폐기물로 배출되게 된다. 전력산업 중 배전분야에서는 2007년 구매한 기자재를 기준으로 연간 13만연 톤의 전력폐기물이 발생될것으로 예측되었으며 이들은 PE, XLPE, FRP, PVC, EPDM, Silicone 등 유기성분이 약 40%, Cu, Al, 철 등 금속과 무기성분이 약 60% 인 것으로 조사되었다. 그러나 전선 및 케이블류를 제외한 기자재를 대상으로 한 분석에서는 유기성분의 함량이 90%에 이르며 이들은 석유화학공업의 원료로부터 만들어지는 특성상 높은 에너지를 함유하는 것으로 나타난 바, 이들을 적정하게 처리하는 방안의 확보는 폐기물의 처리 외에 폐기물로부터 에너지를 회수하여 자원화하는 것이 가능한 것으로 보여진다.