• Steel and Composite Structures
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• v.28 no.3
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• pp.267-278
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• 2018

Structures may need retrofitting as a result of design and calculation errors, lack of proper implementation, post-construction change in use, damages due to accidental loads, corrosion and changes introduced in new editions of construction codes. Retrofitting helps to compensate weakness and increase the service life. Fiber Reinforced Polymer (FRP) is a modern material for retrofitting steel elements. This study aims to investigate the effect of deficiency location on the axial behavior of compressive elements of Circular Hollow Section (CHS) steel short columns. The deficiencies located vertically or horizontally at the middle or bottom of the element. A total of 43 control column and those with deficiencies were investigated in the ABAQUS software. Only 9 of them tested in the laboratory. The results indicated that the deficiencies had a significant effect on the increase in axial deformation, rupture in deficiency zone (local buckling), and decrease in ductility and bearing capacity. The damages of steel columns were responsible for resistance and stiffness drop at deficiency zone. Horizontal deficiency at the middle and vertical deficiency at the bottom of the steel columns were found to be the most critical. Using Carbon Fiber Reinforced Polymer (CFRP) as the most effective material in retrofitting the damaged columns, significantly helped the increase in resistance and rupture control around the deficiency zone.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.350-354
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• 1995

This paper is about impact behavior of cylinder container, made of steel fiber reinforced polymer-impregnated concrete(SFPIC), for intermediate and low level radwaste disposal. In order to obtain the material properties of the SFPIC, steel ball impact tests were done to SFPIC beams and its simulation by finite element method was performed. By using the material properties in finite element impact analysis of the SFPIC concrete cylinder, we obtained impact behavior of the cylinder.

• Journal of Korean Association for Spatial Structures
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• v.5 no.2 s.16
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• pp.7-15
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• 2005

Currently, the structural material, namely glass fiber reinforced polymer (GFRP) is focused on innovative structure due to lightness, excellent workability and noncorrosive characteristics, etc. However, the lack of GFRP connection technology produces only an imitation of steel and wood structures. This uses univentive design principles as well as unsuitable material applications, causes tons of surplus of materials to be wasted, and results in uneconomical structures, because the characteristics between steel and GFRP are completely different. Thus, this research develops the new, innovative GFRP connection system with considerations of the characteristics of GFRP and adopts it to a mobile und modular membrane pavilion.

• Steel and Composite Structures
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• v.31 no.2
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• pp.159-172
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• 2019

Strengthening of civil infrastructure with advanced composites have recently become one of the most popular methods. The use of Fiber Reinforced Polymer (FRP) strips plates and fabric for strengthening of reinforced concrete structures has well established design guidelines and standards. Research on the application of FRP composites to steel structures compared to concrete structures is limited, especially for shear strengthening applications. Whereas, there is a need for cost-effective system that could be used to strengthen steel high-way bridge girders to cope with losses due to corrosion in addition to continuous demands for increasing traffic loads. In this study, a parametric finite element study is performed to investigate the effect of applying thick CFRP strips diagonally on webs of plate girders on the shear strength of end-web panels. The study focuses on illustrating the effect of several geometric parameters on nominal shear strength. Hence, a formula is developed to determine the enhancement of shear strength gained upon the application of CFRP strips.

• Magazine of the Korean Society of Agricultural Engineers
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• v.30 no.1
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• pp.63-72
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• 1988

The primary objective of the study was to find the deformation characteristics of reinforced polymer concrete beams. A test program was carried out to compare the behavior in deformation of polyester and MMA concrete beams with cement concrete beams but with varying ratios of tensile reinforcement. From the results the following conclusions can be made. 1.The various strengths of polymer concrete ware very high compared to the strengths for cement concrete. Also, compared to conventional concrete beams, flexural strength of reinforced polymer concrete beams was distinctly higher for the same section and steel ratios. 2.The polymer concrete beams exhibit large deflections accompanied by relatively high strengths as compared to cement concrete beams. 3.The average ultimate strain at the extreme compression fiber of polymer concrete beams was 0.01 1 cm / cm, and this value was about three to four times as large as that of cement concrete beams, 4.The polymer concrete beams developed more cracks which were more wide crack distribution spacing than the cement concrete beams, and the beams failed in a more ductile manner. 5.The reinforcing steel ratio has a significant effect on the beam strength, load-deflection response, stress-strain curve, and crack pattern of polymer concrete beams.

• Journal of the Korea Concrete Institute
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• v.23 no.3
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• pp.257-264
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• 2011

This paper contains the experimental performance evaluation results of bond-type anchorage systems with the CFRP(carbon fiber reinforced polymer) tendon. The preliminary tests were performed to find the appropriate filling materials in the steel molds. A total of five materials including epoxy or cement mortar have been used as fillers in the steel molds. Results of the preliminary tests showed that specimen filled with non-shrinkage mortar showed maximum tensile strength. Based on the finding, the non-shrinkage mortar was selected as filler for anchoring CFRP tendons. Additional tests were performed as a parametric study to select proper size of steel molds such as external diameter, thickness, and length. The proper size of steel molds with non-shrinkage mortar was selected based on the test results, which gave stable tensile performance.

• Steel and Composite Structures
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• v.43 no.4
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• pp.419-429
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• 2022

In response to the sustainability requirements set in the EU Commission's "Green Deal" towards reduction of the greenhouse gas emissions, it is estimated that the structural design for deconstruction is going to contribute considerably to the sustainable development of the built environment. The demountability of multi-material structural systems basically depends on the shear connectors used in the structural system. This paper focuses on a type of demountable injected shear connector with an injected steel-reinforced resin (iSRR) which consists of spherical steel particles embedded in a resin. Its application to steel-to-concrete and steel-to-Fiber Reinforced Polymer (FRP) decks is presented along with its benefits. In parallel, an overview of the experimental and numerical research on the evaluation of the mechanical properties of the demountable bolted connectors with iSRR is discussed. Last, detailed finite element (FE) models and a parametric study are performed to quantify the confinement level of the SRR material influenced by the oversized hole diameter.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.4
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• pp.107-118
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• 2002

The purpose of this study is to investigate the strengthening effect of RC beams with carbon fiber grid. Carbon fiber grid that is very lightweight and stronger than steel reinforcement does not rust or corrode and has a very high resistance to salt. In this study, five real size specimens which are strengthened with different types of carbon fiber grid are tested. With the results of this tests, we found the physical and mechanical properties of carbon fiber grid and polymer mortar which are used to strengthen the damaged or cracked reinforcement concrete beams. we also investigate the strengthening effect of carbon fiber grid on the five flexural test specimens that have cracks.

• Korean Journal of Materials Research
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• v.3 no.3
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• pp.292-299
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• 1993

In this paper the effects of the length of carbon fiber on the wear properties of carboni carbon composites were investigated. Carbon/carbon composites were fabricated by the liquid impregnation method using the resol-type phenolic resin as a matrix precursor and PAN-based, non-surface treated carbon fiber as a reinforcement. The measured values of the friction coefficient of carbon/carbon composites against AlSl 304 stainless steel ranged from 0.2 to 0.3 under the operating condition used in this study. The effect of the length of carbon fiber on the friction coefficient of carbon/carbon composites were not found. But, it was realized that the wear rate of carbon/carbon composites tends to increase, as the length of carbon fiber increases.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.828-835
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• 2000

In recent years, RC structures need reinforcement due to physical and chemical deterioration, reduction of serviceability and structural capacity. For reinforcement of RC structures, steel plate attachment, area increase and composite fiber sheet attachment methods are used, but there are some problems like weight increase, workability, quality control and fire resistance capacity. This study presents the effectiveness of flexural reinforcement of RC beams using composite rods that are inserted in high strength special purposed polymer mortar.