• Steel and Composite Structures
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• v.30 no.1
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• pp.31-46
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• 2019

In the present study, the various dynamic properties of MWCNT embedded fiber reinforced polymer uniform and tapered composite (MWCNT-FRP) plates are investigated. Various configurations of a tapered composite plate with ply-drop off and uniform composite plate have been considered for the development of the finite element formulation and experimental investigations. First order shear deformation theory (FSDT) has been used to derive the kinetic and potential energy equations of the hybrid composite plates by including the effect of rotary inertia, shear deformation and non-uniformity in thickness of the plate. The governing equations of motion of FRP composite plates without and with MWCNT reinforcement are derived by considering a nine- node rectangular element with five degrees of freedom (DOF) at each node. The effectiveness of the developed finite element formulation has been demonstrated by comparing the natural frequencies and damping ratio of FRP composite plates without and with MWCNT reinforcement obtained experimentally. Various parametric studies are also performed to study the effect of CNT volume fraction and CNT aspect ratio of the composite plate on the natural frequencies of different configurations of CNT reinforced hybrid composite plates. Further the forced vibration analysis is performed to compare the dynamic response of the various configurations of MWCNT-GFRP composite plate with GFRP composite plate under harmonic excitations. It was observed that the fundamental natural frequency and damping ratio of the GFRP composite plate increase approximately 8% and 37% respectively with 0.5wt% reinforcement of MWCNT under CFCF boundary condition. The natural frequencies of MWCNT-GFRP hybrid composite plates tend to decrease with the increase of MWCNT volume fraction beyond 2% due to agglomeration of CNT's. It is also observed that the aspect ratio of the CNT has negligible effect on the improvement of dynamics properties due to randomly orientation of CNT's.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.427-428
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• 2009

In the manufacture process of refrigerator cabinet, polyurethane(PU) liquid firstly is injected between outer plate and inner case in high temperature about $40^{\circ}C$, and PU foam is generated and solidified to the room temperature. There will be great residual stress in the PU foam, especially at the corners after the whole refrigerator is completely assembled. The stress condition will become more complicated under operating condition because of the large temperature difference between the freezing room and outer plate. And also, there are great differences of properties for plastic and steel which would cause different deformation under temperature gradient. The steel outer plate would expand compared to the PU foam or ABS material under operation condition, which induces a thermally bowing deformation in the refrigerator cabinet. The objective of this paper is to design an optimum bead structure or to use reinforcement in the refrigerator except for improving material properties in order to decrease the deformation.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.493-494
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• 2009

Two strengthened columns and an unstrengthened control column were tested to failure under cyclic lateral load combined with a constant axial load to effect of anchorage of T-shaped steel plate in the strengthened column using wire rope units. Main variables considered were anchorage method of T-shaped steel plate. Tested columns were compared with those of conventionally tied columns tested by research of before. Test results showed that lateral load capacity and the displacement ductility ratio of anchorage of T-shaped steel plate in the strengthened column increased 40% and 130% than unstrengthened column, respectively. In particular, at the same effective lateral reinforcement index, a much ductility ratio was observed in the strengthened columns than in the tied columns.

• Steel and Composite Structures
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• v.43 no.1
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• pp.107-116
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• 2022

This paper presents results of numerical studies completed on unreinforced and doubler plate reinforced Elliptical Hollow Section (EHS) T-joints subjected to axial compressive loading on the brace member. Non-linear finite element (FE) models were developed using the finite element code, ABAQUS. Available test data in literature was used to validate the FE models. Subsequently, a parametric study was carried out to investigate the effects of various geometrical parameters of main members and reinforcement plates on the ultimate capacity of reinforced EHS T-joints. The parametric study found that the reinforcing plate significantly increases the ultimate capacity of EHS T-joints up to twice the capacity of the corresponding unreinforced joint. The thickness and length of the reinforcing plate have a positive effect on the ultimate capacity of Type 1 joints. This study, however, found that the capacity of Type 1 orientation is not dependent on the brace-to-chord diameter ratio. As for type 2 orientations, the thickness and length of the reinforcement have a minimal effect on the ultimate capacity. A new design method is introduced to predict the capacity of the reinforced EHS T-joints Type 1 and 2 based on the multiple linear regression analyses.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.495-500
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• 1996

In this paper, it is the effect of using fiber sheet (Carbon Fiber Sheet & Aramid Fiber Sheet) and Steel Plate for reinforced concrete beam, 25 specimens are tested, 16 specimens for bending capacity and the other are for shear capacity. In the case of bending testing, the kind and quantity of the reinforcement materials, the bondage and the existence of crack were selected as experimental variables. And in the case of shear testing, it is testified the effect of reinforcement with the variables of the method of reinforcement (side type and U type). As a result, using the reinforcement meterials can increase the capacity of bending stress.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.23-24
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• 2023

In this study, an easily recyclable separable glued-laminated timber (GLT)-steel beam was developed, and a structural design method was presented. The GLT and steel were mechanically composited using self-tapping screws. The GLT-steel beam was designed to fail in the compression of GLT. The bending moment and load-carrying capacity of the GLT-steel beam were predicted based on composite beam theory and compared with experimental test data. As a result, the GLT-steel beam exhibited ductile behavior, and compression failure of GLT was observed. The screw connection showed no damage while the steel plate was extended. The load-carrying capacity of GLT after failure was similar to the load resistance predicted by the compressive strength of GLT and the tensile strength of steel. This indicates that the ductile behavior of the GLT-steel beam can be safely designed by the tensile strength (yield) of steel.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.589-596
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• 1998

Experimental studies are investigated for RC column retrofitting under cyclic load. Design considerations are jacketing of steel plate of carbon fiber with epoxy bonding, use of unbonded plate, additional concrete grouting, ratio of additional longitudinal steel reinforcement and longitudinal configuration of additional ties. Investigated results are 1) jacketing and additional reinforcements are effective for strengthening, 2) use of additional grouting is less effective with respect to increased section. Future studies are needed to evaluate the requirements about additional reinforcements for member stress level, 3) bond between original and additional grout concrete.

• Journal of Korean Association for Spatial Structures
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• v.7 no.1 s.23
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• pp.79-85
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• 2007

Steel plate bonding method with epoxy is common applied to repair and strengthen RC structures, but Steel is apt to corrode quickly, hard to manufacture and heavy. To overcome these defects, it is carried out research on strengthening RC structures with FRP(Fibre Reinforced Polyrner/Plastic) FRP is generally used in the shape of Plate or Sheet, but it has weak point such as premature failure, difficult work. To cope with these problem, NSMR(Near Surface Mounted Reinforcement) which uses CFRP in the shape of Rod is proposed and carried out active research on strengthening effect of variables such as quantity, anchorage length and space of CFRP-Rod. Strengthening with CFRP-Rod is carried out under loading to some degree in fact, and so the amount of pre-loading is selected as variable in this research. The amount of pre-loading is chosen in proportion to nominal strength of non-strengthened specimen with CFRP-Rod.

• Structural Engineering and Mechanics
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• v.63 no.1
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• pp.125-136
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• 2017

This study investigated the performance of a steel column standing on a reinforced concrete footing when it was subjected to collision of an eight-ton single unit truck. Finite element analyses of the structure with different connection schemes were performed using the finite element model of the truck, and the results showed that the behavior of the column subjected to the automobile impact depended largely on the column-footing connection detail. Various reinforcement schemes were investigated to mitigate the damage caused by the car impact. The probability of the model reinforced with a certain scheme to reach a given limit state was obtained by fragility analysis, and the effects of the combined reinforcement methods were investigated based on the equivalent fragility scheme. The analysis results showed that the reinforcement schemes such as increase of the pedestal area, decrease of the pedestal height, and the steel plate jacketing of the pedestal were effective in reducing the damage. As the speed of the automobile increased the contribution of the increase in the number of the anchor bolts and the dowel bars became more important to prevent crushing of the pedestal.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.1
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• pp.283-292
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• 2005

This paper predicts premature failure load of reinforced concrete beams by epoxy-boned partially steel plates. A parametric study is conducted to estimate premature failure load of beams such as with or without stirrups, unplated length ratio, steel and reinforcement ratio, shear span to depth ratio of reinforcement beam. By results of finite element analysis, it turned out that the unplated length played a dominant role in partially plated beams but reinforcement ratio and shear span to depth ratio effected the premature failure load. The approximate expression with regard to combined design variables is compared with experimental results. It shows closely agreement.