• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.469-474
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• 2003

Recently, to overcome the disadvantages of RC decks, advanced countries such as Japan and USA, and Europe are using prestressing connection precast decks and loop connection precast decks. The prestressing connection precast deck, however, has a weakness against steel corrosion, because of unreliable enforced grouting. The relatively low loading and fatigue capacities of the loop connection precast deck make it difficult to be used for the bridge that requires high fatigue resistance due to the frequent over loaded vehicles. This research proposes the improved connecting method for the precast decks to minimize its shortcomings based on both numerical analyses and full scale model tests. The proposed method maximizes the advantages of precast decks and extends it's service life.

• Computers and Concrete
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• v.18 no.6
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• pp.1083-1096
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• 2016

Beam-column joints are recognized as the weak points of reinforcement concrete frames. The ductility of reinforced concrete (RC) frames during severe earthquakes can be measured through the dissipation of large energy in beam-column joint. Retrofitting and rehabilitating structures through proper methods, such as carbon fiber reinforced polymer (CFRP), are required to prevent casualties that result from the collapse of earthquake-damaged structures. The main challenge of this issue is identifying the effect of CFRP on the occurrence of failure in the joint of a cross section with normal ductility. The present study evaluates the retrofitting method for a normal ductile beam-column joint using CFRP under monotonic and cyclic loads. Thus, the finite element model of a cross section with normal ductility and made of RC is developed, and CFRP is used to retrofit the joints. This study considers three beam-column joints: one with partial CFRP wrapping, one with full CFRP wrapping, and one with normal ductility. The two cases with partial and full CFRP wrapping in the beam-column joints are used to determine the effect of retrofitting with CFRP wrapping sheets on the behavior of the beam-column joint confined by such sheets. All the models are subjected to monotonic and cyclic loading. The final capacity and hysteretic results of the dynamic analysis are investigated. A comparison of the dissipation energy graphs of the three connections shows significant enhancement in the models with partial and full CFRP wrapping. An analysis of the load-displacement curves indicates that the stiffness of the specimens is enhanced by CFRP sheets. However, the models with both partial and full CFRP wrapping exhibited no considerable improvement in terms of energy dissipation and stiffness.

• Journal of Korean Society of Steel Construction
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• v.17 no.3 s.76
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• pp.347-356
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• 2005

Recently, pre-engineering building (P.E.B.) systematic frames are increasingly being used in steel factory buildings, but almost of the related techniques are dependent on the engineering program (e.g, MBS, LTI), which is usually imported from other countries. These are designed under the AISC-ASD because at present there is no Korean design code for P.E.B. frames. Also, there are few studies onbehaviour and we need to develop the element techniques by using H-shaped components.In particular, there is a tendency towards overestimated design because column-rafter connections have been designed with extended end plate type joint, which is treated asrigid joint,so structural examinations are needed. Therefore, this study represents a basic step in ascertaining the application of P.E.B. systematic frames by using H-shaped column-rafter connectionwith flush type end plate. Its structural performance is compared with that of existing extended type joint using a structural performance test. The structural behaviour of specimen was understood qualitatively and the possibility of application (e.g, design aid charts) of semi-connection (flush type) with H-shaped column-rafter was determined.

• KIEAE Journal
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• v.16 no.3
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• pp.103-112
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• 2016

Recently, many New Han-oks have been constructing in all over the country to popularize as a type of green house. But, achievement of thermal performance of external wall is still the very important issue to become popular. Purpose: The purpose of this study is to verify the thermal performance level of modern New Han-ok through Temperature Difference Ratio inside(TDRi) analysis at corners of the external wall in Han-ok. Method: To achieve this goal, measurements were carried out in 12 Han-oks(experimental mock-up(1), exhibition Han-ok(1), happy village Han-oks(10)) by taking a infra-red thermography using thermal video system. Following are analysis items about connection joint between wall and wood columns of external wall conditions; the part between external wall and external wall(2D), external wall and ceiling(or floor)(2D), 2 external walls and ceiling(or floor)(3D) and so on. Result: It was analyzed that the probability of condensation at most of connection joint appear high and TDRi of 3D corners is higher than that of 2D corners in general. It means that the development of construction techniques about connection joint between wood columns and external wall is still required. The results of this study may be used to improve the construction technology of new Han-ok and as a basis for the specifying the desired thermal comfort environment of dwelling.

• Steel and Composite Structures
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• v.16 no.4
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• pp.417-436
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• 2014

During an earthquake, steel frame columns can be subjected to high axial forces combined with inelastic rotation demand resulting from story drift. Generally, the whole beam or component can be represented with one element. In elasto-plastic analysis, subdivision is necessary if the plastic deformation occurs within two ends of beams. If effects of the joint panel are necessarily considered in the analysis, the joint panel should be represented with an independent element. It is a special element to represent the shear deformation of the joint panel in the beam-column connection zone. Several analytical models for panel zone (PZ) behavior exist, in terms of shear force-shear distortion relationships. Among these models, the Krawinkler PZ model is the most popular one which is used in the AISC code. Some studies have pointed out that Krawinkler's model gives good results for the range of thin to medium column flanges thickness. This paper, introduces a new model to estimate the response of shear force-shear distortion for the PZ including column axial force. The model is applicable to both thin and thick column flange. To achieve an appropriate PZ mathematical model first, the effects of PZ strength and stiffness on connection response are parametrically studied using finite element models. More than one thousand and four-hundred beam-column connections are included in the parametric study, with varied parameters; then based on analytical results a simple mathematical model is presented. A comparison between the results of proposed method herein with FE analyses shows the average error especially in thick column flange is significantly reduced which demonstrates the accuracy, efficiency, and simplicity of the proposed model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.314-319
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• 2010

This paper represents the results of study on Extra High Voltage Power Cable Connection System Development. The purpose is to evaluate structural safety by numerical analysis for the relaxation of electric field concentration and by structural analysis of Carrier Pipe for easy installation of High Insulating Rubber Sleeve in the field, which is core technique of connection system. According to the results, the thickness of Carrier Pipe needs at least 9mm by optimization analysis of deformation behavior and insulating design & relaxation of electric field concentration. The result of contraction behavior of the connection part can be demonstrated with the same result of electric field relaxation analysis at the boundary of the electrode inserted into the insulating rubber sleeve.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.2
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• pp.197-206
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• 2006

Statement of problem: One of common problems associated with single teeth dental implant prosthetic is the loosening of screws that retain the implants. Purpose: The maintenance of screw joint stability is considered a function of the preload achieved in the screw when the suggested initial tightening torque is applied. The purpose of this study was to investigate acquired preload after initial clamping torque for estimating screw joint stability. Material and methods: A comparative study on the effect of initial clamping of two types of implant systems with different connections was conducted Three dimensional non-linear finite element analysis is adopted to compare the characteristics of screw preloads and stress distributions between two different types of implant systems composed with abutment, screw, and fixture under the same loading and boundary conditions. Results: 1. When the initial clamping torque of 32Ncm was applied to the implant systems, all types of implants generated the maximum effective stress at the first helix region of screw. 2. Morse taper connection types of implants generate lower stress distributions compared to those by butt joint connection types or implants due to large contact surface between abutment and fixture. 3. The internal types of implant systems with friction grip type implant systems have higher resistance to screw loosening than that of the external types of implant systems since the internal types of implant systems generated larger preload than that generated by the external types for the same tightening moments.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.6
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• pp.119-128
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• 2008

In this study, new moment-resisting precast concrete beam-column joint is proposed for moderate seismic regions. It has the connection reinforcing bars, penetrated the joint and lap-spliced with the bottom bars of precast U-shaped PC beam. To evaluate the performance for noncontact lapped splice, experimental and analytical works were conducted. Major variables for tests are the length of lap, the diameter of connection reinforcing bars, and the distance between lapped bars. Analytic research was performed nonlinear finite element method. Analytic research focused on crack pattern, load-deflection curve, comparison of internal force, evaluation of ductility strains of reinforcement bar. Results of experimental and analytical works show that the these variables has much influence on flexural strength and ductility, and joint behavior.

• Journal of the Korean Society of Industry Convergence
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• v.9 no.2
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• pp.155-160
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• 2006

합성상판을 시공하는 경우 교축방향에 분할된 저강판을 접합 일체화해야 한다. 본 논문에서는 강 콘크리트 합성상판을 대상으로 3종류의 배력철근 방향 이음구조를 제안하며, 보 공시체에 의한 정적 정점피로 실험한다. 그 결과 보의 피로실험 결과 저강판 혹은 고력볼트가 피로파단 하였으며, 3차원 FEM해석에 이음부의 휨 강성도 및 피로강도에 대해서 해석적으로 검토된다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.1
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• pp.77-89
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• 2020

Submerged floating tunnel (SFT) is a type of tunnel that allows tunnel segments to float underwater by buoyancy, and is being actively studied in recent years. When the submerged floating tunnel is connected to the ground, the tunnel and the bored tunnel inside the ground must be connected. There is risk that the stress will be concentrated at the connection between the two tunnels due to the different constraints and behavior of the two tunnels. Therefore, special design and construction methods should be applied to ensure the stability around the connection. However, previous studies on the stability at the connection site have not been sufficiently carried out, so study on the basic stage of the stability at connection site are necessary. In this study, numerical analysis simulating the connection between submerged floating tunnel and the bored tunnel confirmed that the shear strain concentration occurred in the ground around the connection, and it was analyzed that the structural factors can be handled during construction to have effects on the stability of the ground around the connection. Numerical results show that the risks from disproportionate displacements in the two tunnels can be mitigated through the construction of grouting material and joint design. Although the results from this study are qualitative results, it is expected that it will contribute to the determination of structural factors and risk areas that should be considered in the design of connections between the submerged floating tunnel and bored tunnel in the future studies.