• Journal of Korean Society of Steel Construction
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• v.26 no.1
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• pp.1-10
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• 2014

In this study, out-of-plane flexural test was performed to analyze behavior properties for a beam specimen which imitated a structure with connection member between reinforced concrete and steel plate concrete part. Tie bars between a upper and a lower steel plate, and tie wide flange shapes between upper and lower ribs were designed to prevent the steel plate or the ribs from breakaway in the connection of the specimen. As a result of the test, ductile failure behavior of the specimen and the functionality of the tie members were conformed as originally intended. Also, tension tests were performed to evaluate the design appropriateness of two specimens produced to anchor and connect mechanically #14 bars. The two test results showed that the anchorage connection system behaves in elastic limit during the main bars yielded, and the integrity of the designed system was verified.

• Composites Research
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• v.13 no.1
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• pp.1-10
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• 2000

During the compression molding process of the continuous fiber-reinforced polymeric composites, two main problems such as fiber-matrix separation and fiber orientation are produced by the difference of flow velocity. Molded parts are lead to be nonhomogeneous and anisotropic. As the mechanical property of the products are dependent on the separation and orientation, it is important to research the fiber mat structure and molding condition. If the fiber mat structure is changed by the increment of needling, the separation decreases and after compression molding the orientation is easily aligned. As it were, the compression moldability is good. But the defects as tears, thin thickness are produced in the products. Therefore, it is important to clarify the moldability in relation to the usage of products and the expenses of produce on the actual process. Therefore we must make the measurement methods that can define the moldability of products. In this research, the effects of the fiber mat structure(NP = 0, 5, 10, 25, 50 punches/$cm^2$) and the mold geometry($r_p$ = 1, 25, 50 mm) on the moldability of products were discussed. We investigated the case of one-dimensional flow in order to obtain the degree of nonhomogeneity and the fiber orientation function. In result, we could gain the correlation coefficient of the continuous fiber-reinforced polymeric composites. Also we experimented on the cup-type compression molding which was appeared the wrinkle on the flange part by the complex stress condition in order to gain the degree of nonhomogeneity and area ratio. In result, the moldability of products was expressed as the correlation coefficient and area ratio.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.4
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• pp.263-270
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• 2020

This study evaluates the structural behavior of connected long-span beams applied for excavation in urban areas with a narrow street. Generally, the reliability of the connection is reduced owing to the defect of the upper flange in the connection. An improved connection part was developed to complement the defects in the connected long-span beam. A finite element analysis based on a commercial program, ABAQUS, was employed to evaluate the behavior of the improved connection part. A numerical analysis model was proposed to analyze the high-strength bolt connection and the composite behavior of steel and concrete applied to the improved connection. The suitability of the proposed numerical analysis was verified by comparing the experimental and numerical analysis results of the references. Using the proposed numerical analysis method, the improved and general connections were analyzed and compared with each other. The stress distribution and elastic-plastic behavior of the long-span beam were analyzed numerically. The analysis confirmed that 25% of the compressive stress was improved, resulting in the improvement of structural safety and performance.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.3
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• pp.65-79
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• 1992

This study is concerned with the optimal design of two hinged steel arches with I cross sectional type and aimed at the exact analysis of the arches and the safe and economic design of structure. The analyzing method of arches which introduces the finite difference method considering the displacements of structure in analyzing process is used to eliminate the error of analysis and to determine the sectional force of structure. The optimizing problems of arches formulate with the objective functions and the constraints which take the sectional dimensions(B, D, $t_f$, $t_w$) as the design variables. The object functions are formulated as the total weight of arch and the constraints are derived by using the criteria with respect to the working stress, the minimum dimension of flange and web based on the part of steel bridge in the Korea standard code of road bridge and including the economic depth constraint of the I sectional type, the upper limit dimension of the depth of web and the lower limit dimension of the breadth of flange. The SUMT method using the modified Newton Raphson direction method is introduced to solve the formulated nonlinear programming problems which developed in this study and tested out throught the numerical examples. The developed optimal design programming of arch is tested out and examined throught the numerical examples for the various arches. And their results are compared and analyzed to examine the possibility of optimization, the applicablity, the convergency of this algorithm and with the results of numerical examples using the reference(30). The correlative equations between the optimal sectional areas and inertia moments are introduced from the various numerical optimal design results in this study.

• Journal of the Korea Concrete Institute
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• v.21 no.3
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• pp.319-326
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• 2009

Two parallel wide flange built-up beams are widely used as struts in resisting lateral earth pressure because of the effectiveness in structure and construction. In a certain structural system, the reinforced concrete columns are to be placed at the intersection where two perpendicular beams cross each other, the square part of the joint being filled with concrete. In the punching shear mechanism of the beam-column joint, the radial deformation caused due to shear cracking will be constrained by the spring action of the squarely encompassed beam flanges. As a result, the punching shear strength of the joint concrete can be expected to be increased. To verify this phenomenon experiments have been performed for various constraining elements and distances between columns and constraints. Test results are compared with the approximation analysis formula which has been proposed in this study, based on the code formula. The results calculated by the proposed equation show comparatively close agreement with the punching shear strength detected from the test.

• Journal of Korean Society of Steel Construction
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• v.20 no.6
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• pp.731-740
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• 2008

This paper deals with the fatigue behavior and strength of a new-type of steel-concrete composite bridge deck. The new-type composite bridge deck consists of corrugated steel plate, welded T-beams, stud-type shear connectors and reinforced concrete filler. A total of eight composite bridge deck specimens were fabricated, the fatigue tests were conducted under four-point bending test with three different stress ranges in constant amplitude. According to the test results, the fatigue crack generated at the welding part of the corrugated steel plate, progressed down to the bottom of the steel plate and encountered the crack, which came out from the opposite side at the same position. After the two cracks were connected at the bottom of the steel plate, the lower flange was cut off and the fatigue crack developed up to the T-beam. And the displacements and strains of fatigue test specimens were increasing with cyclic loading number, these were changed sharply at the fatigue failure. The fatigue results are compared with the design S-N curves specified in the Korea Highway Bridge Design Specifications and data in NCHRP 102 and NCHRP 147 report. The new-type composite bridge deck has a stress category of C, which means that new-type composite bridge deck can be designed by the current fatigue design specifications provided for steel members.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.5
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• pp.380-387
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• 2014

Piper Alpha disaster drew attention to the damage likely to arise from explosions and fires on an offshore platform. And great concerns have been increased to prevent these hazards. Blast wall is one of the passive safety systems; it plays a key part of minimizing the consequences. However, a buckling due to explosion loads is a factor which can reduce the strength of blast wall. The buckling often occurs between web and flange at the center of blast wall. This study aims to find a solution for reinforcing its strength by installing a flat plate at the spot where the buckling occurs. First of all, ANSYS finite element method is adopted to numerically compute the structural resistance characteristic of blast wall by using a quasi-static approach. Sequentially, the impact response characteristics of blast wall are investigated the effect on thickness of flat plate by using ANSYS/LS-DYNA. Finally, pressure-impulse diagrams (P-I diagram) are presented to permit easy assessment of structural response characteristics of stiffened blast wall. In this study, effective use is made to increase structural intensity. of blast wall and acquired important insights have been documented.

• Journal of Korean Society of Steel Construction
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• v.17 no.4 s.77
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• pp.419-429
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• 2005

The objective of this study is to clarify the structural features of members consisting of a connection, as part of the previous study on the CFT column-to-beam tensile connection with a combined cross diaphragm. This connection has the following merits: it evenly distributes the stress on the beam flange and the diaphragm and reduces the stress concentration by improving the stress transfer route and restraining the abrupt deformation of the diaphragm. Finite element analysis was performed to find out the stress transfer through the sleeve, which is an important member of the connection with a combined cross diaphragm. The length and thickness of the sleeve were used as variables for the analysis. The analysis results showed that the length and thickness of the sleeve did not influence the capacity of the connection and played the role of a medium for the transfer of the stress from the diaphragm to the filled concrete. It was proposed that the appropriate length of the sleeve have the same value as the diameter of the sleeve and that the appropriate ratio of the sleeve diameter to the sleeve thickness be 20. Two equations for the evaluation of the load carrying the capacity of the connection were also proposed through the modification of the evaluation equation suggested in the previous study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.134-141
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• 2019

This paper is a study on design improvement of rotorcraft horizontal stabilizer. The rotorcraft horizontal stabilizer stabilizes the behavior of the pitch, yaw, etc. from the aircraft. Because of this role, horizontal stabilizers are a major component (Flight Safety Part) that affects flight safety on rotorcraft. However, when the rotorcraft was operated in domestic, cracks were found in the inner structure of the horizontal stabilizer and design improvement was needed. In this paper, we identified the two causes of the horizontal stabilizer crack defects through fracture analysis and structural analysis. The first is the tightening torque when the bolt is tightened, and the second is the lead-lag behavior of aircraft. In order to improve these two causes, bolt fastening method, flange structure and thickness were changed and composite ring was applied. In order to verify the design improvement, the structural analysis was performed and the structural strength was improved. Also Fatigue analysis of the internal structure (Rib 1) was performed and it was confirmed that the requirements were satisfied.

• Journal of the Society of Disaster Information
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• v.16 no.4
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• pp.796-805
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• 2020

Purpose: A static loading test was performed to evaluate the ultimate flexural strength of a girder in which 80MPa high-strength concrete was synthesized on the compressive flange of the I-shape steel girder. Method: This test is designed and fabricated two types of specimens with different shear-connection specifications, and evaluated their ultimate flexural behavior until reaching the extreme event limit states. In addition, the ultimate strength was evaluated by comparing the test results and the results of the strain compatibility method. Result: By confirming the displacement within 0.02mm as a result of the relative slip measurement, it was verified that the two specimens secured perfect bonding. Therefore, the difference in the shear specification does not have a great effect on the stiffness, and if the specimens are completely synthesized, there is no difference in the behavior until it reaches the extreme-event limit states. Conclusion: The girder to be tested has a working load within the elastic range and meets the usability requirements for allowable deflection. Therefore, even if a part of the casing is subjected to the tensile force at the level of cracking, the deck will first reach the compression failure due to the role of the reinforcing bar.