• Journal of the Korean Society for Advanced Composite Structures
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• v.4 no.1
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• pp.40-46
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• 2013

This paper presents the design, fabrication and performance of a reinforced concrete beam strengthened by GFRP box plate and its possibility for structural rehabilitations. The load capacity, ductility and failure mode of reinforced concrete structures strengthened by FRP box plate were investigated and compared with traditional FRP plate strengthening method. This is intended to assess the feasibility of using FRP box plate for repair and strengthening of damaged RC beams. A series of four-point bending tests were conducted on RC beams with or without strengthening FRP systems the influence of concrete cover thickness on the performance of overall stiffness of the structure. The parameters obtained by the experimental studies were the stiffness, strength, crack width and pattern, failure mode, respectively. The test yielded complete load-deflection curves from which the increase in load capacity and the failure mode was evaluated.

• Steel and Composite Structures
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• v.18 no.4
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• pp.811-831
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• 2015

This paper focuses on the strengthening methods used for improving the compression behaviors of perforated box-section walls as provided in the anchorage zones of steel pylons. Rectangular plates containing double-row continuous elliptical holes are investigated by employing the boundary condition of simple supporting on four edges in the out-of-plane direction of plate. Two types of strengthening stiffeners, named flat stiffener (FS) and longitudinal stiffener (LS), are considered. Uniaxial compression tests are first conducted for 18 specimens, of which 5 are unstrengthened plates and 13 are strengthened plates. The mechanical behaviors such as stress concentration, out-of-plane deformation, failure pattern, and elasto-plastic ultimate strength are experimentally investigated. Finite element (FE) models are also developed to predict the ultimate strengths of plates with various dimensions. The results of FE analysis are validated by test data. The influences of non-dimensional parameters including plate aspect ratio, hole spacing, hole width, stiffener slenderness ratio, as well as stiffener thickness on the ultimate strengths are illustrated on the basis of numerous parametric studies. Comparison of strengthening efficiency shows that the continuous longitudinal stiffener is the best strengthening method for such perforated plates. The simplified formulas used for estimating the compression strengths of strengthened plates are finally proposed.

• Journal of the Korean Institute of Rural Architecture
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• v.7 no.1
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• pp.121-128
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• 2005

This experimental study was conducted to investigate beam strengthening of RC buildings with expended steel plate(ESP) in rural area. Nine test specimens were manufactured, whose variables were tensile steel ratio and the amount and the shape of expanded steel plate. The test results indicated that strengthened beams with ESP showed the improvement of flexural strength of 50%~90%, and the beam strengthening of U type was excellent for shear reinforcement as well as flexural reinforcement, more over, the honeycomb shape of ESP and anchor bolts for development of ESP were very effective.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.328-333
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• 1996

Concrete can be defective for several reasons, including an inadequate design, material selection of workmanship, failure to appreciate the hazards associated with prevailing enviromental conditions. Concrete can also deteriorate or be damaged in use. Thus, it is necessary to evaluate the safety of existing concrete strucutres. On the basis of these reasons, they must be performed for repair or rehabilitation. Presently, strengthening methods of R/C structure used in Korea, are an enlargement of concrete member, strengthening with steel plate or CFRP on the R/C structure. It has been widely estabilished that strengthening effect of CFRP is superior to steel plate in terms of it's lighter unit weight and higher tensile strength. But there are no construction results of CFRP on the civil R/C structure in Korea. The strengthening design technique with CFRP, it's const겨ction, and it's strengthening effect for deteriorated R/C rahmen bridge is introduced in this paper.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.1272-1277
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• 2009

Since improved capacity for RC bridges has been required due to deterioration or increase in traffic, the deflection of cracked reinforced concrete slabs need to be reconsidered. Strengthening is known as the better way to improve capacity of bridges than reconstructing. In this paper, Fiber Reinforced Plastic (FRP) was introduced as one of the best strengthening methods for civil structures. The structures strengthened with FRPs can improve the strengthening capacity and serviceability. Therefore, CFRP sheet and Glass Fiber-Steel Composite Plate (GSP) in this research were used for strengthening slabs of RC bridges. Experimental data from the strengthening will be helpful to better understand the effect of the strengthening and effective flexural rigidity.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.133-136
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• 2005

Experimental research was conducted to investigate the characteristic of various CFRP strengthening methods. A total of 4 specimens of 3.3m length were tested in four point bending after strengthening them with externally bonded CFRP plates. The CFRP plates were bonded without prestress or with prestress levels of CFRP plate strain $0.5\%$. The non-prestressed specimen without anchor plate failed by separation of the plate from the beam due to premature debonding while the non-prestressed specimen with anchor plate failed by CFRP fracture and showed the significant increase of ductility capacity. In addition, the prestressed specimens failed by concrete compression failure. The maximum load and ductility capacity were most significantly increased.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.721-724
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• 1999

The concrete structure under fatigue load depresses in mechanical capability or breaks down finally because of the fatigue. So recently the study on strengthening methods using bonded plate is widely attended. Which could be constructed under use and without damaging the structure. The intention of this method is to increase the useability of the structure and to recover the strength. So application on fields are sharply increasing. In this study it is tried to develop strengthening methods using notches and anchor bolts which could supply the defect on falling off of the plate at the end.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.703-708
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• 1999

The concrete structure under fatigue load depresses in mechanical capability or breaks down finally because of the fatigue. So recently the study on strengthening methods using bonded steel plate is widely attended. Which could be constructed under use and without damaging the structure. The intention of this method is to increase the useability of the structure and to recover the strength. So application on fields are sharply increasing. In this study it is tried to develop strengthening methods using notches and anchor bolts which could supply the defect on falling off of the steel plate at the end.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.697-700
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• 1999

Strengthening existing structure using the exterior steel wire is utilized because of their high adaptability and strengthening efficiency. In the practical aspect, the fixing methods, which are generally adopted have caused problems. A new method is not easily designed because of the weak points, a limit of tension stress, and complex transmit processes. To make up for the weak points in the current fixing method, tensile end bracket similar to a supporting plate has been developed, but the tensile end bracket was relatively big because of increasing length welded between the end plate and the resisting plate.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.121-124
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• 2008

The purpose of this study is to evaluate the critical strengthening ratio of concrete railroad bridge strengthened with NSM using CFRP plate. The railroad bridge is usually under vibration and impact in service state. Therefore, it is important that the effective strengthening performance must be exhibited under the service loading is acted. To widely apply the NSM method for the concrete railroad bridge in field, it needs that reasonable strengthening parameter such as strengthening ratio has to be investigated and evaluated when the strengthening design is conducted. In this study, to suggest more reasonable strengthening ratio, material and geometrical uncertainty was considered and applied by Monte Carlo Simulation (MSC) technique. Lastly, the critical strengthening ratio of concrete railroad bridge strengthened with NSM using CFRP plate was evaluated by using the limit state function with the target reliability index.