• Journal of the Korean Geosynthetics Society
• /
• v.15 no.3
• /
• pp.67-76
• /
• 2016

The railway bridge abutment subjected to the lateral earth pressure is a sensitive structure that is affected by backfill materials, installation methods, compaction, and drainage system and so on. The several design loads for the bridge abutment design consist of traffic loading on bridges and vertical & lateral force due to surcharge load at backfill. Especially, the lateral earth pressure of design load components is important and considered in the design of geotechnical engineering structure such as bridge abutment wall. The determination of cross section for abutment is finally determined with calculating external stability and member force of abutment wall structures. In this study, the abutment wall height is 12m and the optimal cross section of abutment wall has been determined that satisfies an external stability for abutment structure through friction angles of 35, 40, and 45 degrees of backfill materials. The external stability and member force of abutment wall with friction angle of backfill materials and were calculated and construction cost of each abutment wall structures was compared. It found that the construction cost was reduced from 2.2 to 8.4% with friction angle of backfill materials.

• Journal of the Korea Concrete Institute
• /
• v.22 no.4
• /
• pp.535-546
• /
• 2010

Recently, the probability of collision accident between vehicles or vessels and infrastructures are increasing at alarming rate. Particularly, collision impact load can be detrimental to sub-structures such as piers and columns. The damaged pier from an impact load of a vehicle or a vessel can lead to member damages, which make the member more vulnerable to impact load due to other accidents which. In extreme case, may cause structural collapse. Therefore, in this study, the vehicle impact load on concrete compression member was considered to assess the quantitative design resistance capacity to improve, the existing design method and to setup the new damage assessment method. The case study was carried out using the LS-DYNA, an explicit finite element analysis program. The parameters for the case study were cross-section variation of pier, impact load angle, permanent axial load and axial load ratio, concrete strength, longitudinal and lateral rebar ratios, and slenderness ratio. Using the analysis results, the performance based resistance capacity evaluation method for impact load using satisfaction curve was developed using Bayesian probabilistic method, which can be applied to reinforced concrete column design for impact loads.

• Steel and Composite Structures
• /
• v.19 no.1
• /
• pp.21-41
• /
• 2015

Push-out tests have been conducted on 18 rectangular concrete-filled steel tubular (CFST) columns with the aim of studying the bond behaviour between the steel tube and the concrete infill. The obtained load-slip response and the distribution of the interface bond stress along the member length and around the cross-section for various load levels, as derived from measured axial strain gradients in the steel tube, are reported. Concrete compressive strength, interface length, cross-sectional dimensions and different interface conditions were varied to assess their effect on the ultimate bond stress. The test results indicate that lubricating the steel-concrete interface always had a significant adverse effect on the interface bond strength. Among the other variables considered, concrete compressive strength and cross-section size were found to have a pronounced effect on the bond strength of non-lubricated specimens for the range of cross-section geometries considered, which is not reflected in the European structural design code for composite structures, EN 1994-1-1 (2004). Finally, based on nonlinear regression of the test data generated in the present study, supplemented by additional data obtained from the literature, an empirical equation has been proposed for predicting the average ultimate bond strength for SHS and RHS filled with normal strength concrete.

• Journal of the Korea Concrete Institute
• /
• v.14 no.6
• /
• pp.892-899
• /
• 2002

Among the methods for enhancement of load-carrying capacity on flexural concrete member, recently, a concept is being investigated which replaces the steel in a conventional reinforced concrete member with a fiber reinforced polymer(FRP) shell. This study focuses on modeling of the structural behavior of concrete surrounded with FRP shells in flexural bending members. A numerical model of fiber cross-sectional analysis is proposed to predict the stress and deformation state of the FRP shell and concrete. The stress-strain relationship of concrete confined by a FRP shell is formulated to be based on the constitutive law of concrete in multi-axial compressive stress state, in assuming that the compression response is dependent on the radial expansion of the concrete. To describe the FRP shell behavior, equivalent orthotropic properties of in-plane behavior from classical lamination theory are used. The present model is validated to compare with the experiments of 4-point bending tests of FRP shell concrete beam, and has well predicted the moment-curvature relationships of the members, axial and hoop strains in the section, and the enhancement of confinement effect in concrete surrounded by FRP shell.

• Korean Journal of Construction Engineering and Management
• /
• v.21 no.1
• /
• pp.40-49
• /
• 2020

This study analyzed the factors affecting the ruling of litigation on the housing reconstruction and housing redevelopment project based on the cross analysis and logistic regression analysis. According to cross analysis result, the defensive process prerequisite group was showed significant in many variables which were past legal relation, no ownership or association member status, double lawsuit, abuse of lawsuit right·litigation trust, existence of claim-preclusion, no standing to sue·no standing to be sued, lapse of litigation period, no legal interest, no own defect of approval. On the other hand, the offensive cause of action group was found to have no significant variable. According to logistic regression result, the defensive process prerequisite group was showed significant in many variables which were past legal relation, no standing to sue·no standing to be sued, no ownership or association member status, double lawsuit, no own defect of approval, abuse of lawsuit right·litigation trust, existence of claim-preclusion. Meanwhile, the offensive cause of action group was showed significant in only one variable that was defect in relation with articles of association. Overall, it is noteworthy that the offensive cause group showed very low significant results compared with the defensive process prerequisite group.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.6
• /
• pp.39-46
• /
• 2022

As the limit state design method is applied as the design method of reinforced concrete structure, the ultimate state is considered when analyses or designing. In fact, when the reinforced concrete member is bent, there is a confining effect by stirrup, but the material curve of unconfined concretes applied when designing. In this study, to evaluate the suitability of the confined concrete model for flexural members, a 4-point bending test was conducted on RC simple beam with a double-reinforced rectangular cross-section, and the behavior of the member after yield was analyzed in detail using image processing method. For detailed analysis, the DIC method was adopted as an image analysis method, and the validity of DIC method was verified by comparing the measurement results with the LVDT. The distribution of the strain on the concrete surface calculated as a result of the DIC method could be obtained, and the average strain distribution of the cross-section was calculated. Using the average strain distribution, the stress distribution applied existing confined concrete model as a material curve could be derived. Through the comparison of the experimental results and the existing model application results, the suitability of the confined concrete model for RC flexural members having a rectangular cross-section was evaluated.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.10
• /
• pp.1670-1674
• /
• 2007

Addition reactions of anilines (XC6H4NH2) to β-nitrostilbene (YC6H4CH=C(NO2)C6H4Y') have been investigated in acetonitrile at 30.0 oC. The magnitude of βX values (=0.11-0.34) indicates relatively earlier transition state for additions with anilines than with benzylamines. The signs of ρY and ρY' are positive with Δρ = ρY?ρY' = 0.04, demonstrating a TS imbalance with a negative charge development on the Cβ in the TS. The signs of cross-interaction constants ρXY (<0), ρXY' (<0) and ρYY' (>0) are consistent with bond forming and breaking processes. The relatively weak normal kinetic isotope effects involving deutarated nucleophiles, kH/kD>1, suggest an early, hydrogen-bonded, 4-member cyclic TS.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2000.04a
• /
• pp.93-96
• /
• 2000

The theory of non-prismatic folded plate structures was reported by the senior author in 1965 and 1966. Fiber reinforced composite materials are strong in tension. The structural element for such tension force is very thin and weak against bending because of small bending stiffnesses. Naturally, the box type section is considered as the optimum structural configuration because of its high bending stiffnesses. Such structures can be effectively analyzed by the folded plate theory with relative ease. The "hollow" bending member with uniform cross-section can be treated as prismatic folded plates which is a special case of the non-prismatic folded plates. Tn this paper, the result of analysis of a folded plates with one box type uniform cross-section is presented. Each plate is made of composite laminates with fiber orientation of [ABBCAAB]$_r$, with A=-B=$45^{\circ}$, and C=$90^{\circ}$. The influence of the span to depth ratio is also studied. When this ratio is 5, the difference between the results of folded plate theory and beam theory is 1.66%. is 1.66%.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.7-8
• /
• 2010

The temperature development of a structural element is dependent on section factor, which is estimated as a ratio of the fire-exposed perimeter to the cross-section area. Hence, with the higher section factor, the faster temperature development of the section os observed. Composite beam member, partially embedded asymmetry H beam, has a good fire resistance to the cross-section. The study was intended to conduct with change with section factor. The experimental result of section type which the Slim Beam Floor is bottom flange reinforced method.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.23-27
• /
• 1997

This paper introduces the structural design optimization of a high speed machining center using multi-step optimization combined with G.A.(Genetic Algorithm) and Weighted Method. In this case, the design problem is to find out the best design variables which minimize the static compliance, the dynamic compliance, and the weight of the machine structure simultaneously. Dimensional thicknesses of the thirteen structural members of the machine structure are adopted as design variables. The first step is the cross-section configuration optimization, in which the area moment of inertia of the cross-section for each structural member is maximized while its area is kept constant The second step is a static design optimization, In which the static compliance and the weight of the machine structure are minimized under some dimensional and safety constraints. The third step IS a dynamic design optimization, where the dynamic compliance and the structure weight are minimized under the same constraints. After optunization, static and dynamic compliances were reduced to 62.3% and 95.7% Eorn the initial design, while the weight of the moving bodies are also in the feaslble range.