• Title/Summary/Keyword: 정적응력해석

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A Study on the Continuation Effect of the PC Beam Bridge Reinforced by Span-Jointing of Slab (PC Beam 교의 슬래브 연속화 보강 효과에 대한 연구)

  • Sun, Chang-Ho;Lee, Jong-Seok;Kim, Ick-Hyun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.6 no.4
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    • pp.225-232
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    • 2002
  • Recently the slab span-jointing method has been employed as one of the retrofit technologies to enhance the capacity of existing simple beam bridges in many cases. In general this method makes simple beam bridges behave like multi-span continuous bridges under service loads excluding self weight in company with external prestress force method in the field. In this paper the continuation effect has been studied for the retrofitted bridges by the experimental and numerical approaches. The results show that the deflections and stresses of members are reduced due to the increase of the total stiffness of bridge system and the efficiency of bridge continuation based on the slab span-jointing method is about 40 % when comparing with the case of continuous bridges.

On the Grounding Damage of Ship Bottom Stiffened Platings(Part II : Damage Prediction Formula) (좌초시 선저보강판의 손상에 관한 연구(제2보 : 손상추정식))

  • Jeom-Kee Paik;Tak-Kee Lee
    • Journal of the Society of Naval Architects of Korea
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    • v.31 no.4
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    • pp.119-129
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    • 1994
  • The aim of the present study is to derive an empirical formula relating the absorbed energy and the cutting length for longitudinally stiffened steel palates which are cut by a wedge, idealizing the ship bottom stiffened platings in groundings. This study is based on the test results and the investigations of some parameters affecting the cutting response, described in Part I. By dimensionless ana1ysis of the test results obtained in a quasi-static loading condition, the energy absorbed while a longitudinally stiffened plate is cut by a wedge is expressed as functions of the cutting length, the yield stress, the equivalent plate thickness and the wedge angle. Also, the dynamic effects are incorporated into the static formula such that the proposed formula can be applied to the impact loading situations. The validity of the proposed formula is checked by comparing with the results obtained by the other existing formulas or by the drop-hammer tests.

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Splice Performance Evaluation of Fastening Coupler According to the Slope Length of Internal Fasteners (조임쇠 경사길이에 따른 체결식 커플러의 이음성능 평가)

  • Jung, Hyun-Suk;Choi, Chang-Sik
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.26 no.4
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    • pp.11-19
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    • 2022
  • In this study, in order to improve the splice performance of mechanical couplers, two new mechanical couplers with different connection modes were developed with rebar(SD400). The stress analysis of mechanical couplers with two different connection modes was carried out. Uniaxial tensile tests were carried out with type of steel, connection mode and the slope length of internal fastener as variables to analyze the influence on the maximum tensile strength. Building upon this previous work, the specimens that met the code in uniaxial tensile test were fabricated and static loading test and cyclic loading test were performed on the basis of Korean code(KS D 0249). The results of this research are as follows; (1) The tensile strength of steel and the slope length of internal fasteners have a certain influence on the maximum tensile strength. (2) The connection mode has some influence on the stiffness, slip and stiffness reduction rate of the connecting rebars. The results verify the feasibility of the proposed enhanced mechanical coupler in the field.

A Study on Transferred Load Reduction on Paved Track Roadbed with Low Elastic Base Plate Pad (저탄성 베이스플레이트 패드 적용에 따른 포장궤도 노반에서의 전달하중 저감에 관한 연구)

  • Lee, Il-Wha;Kang, Yun-Suk;Lee, Hee-Up
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.3D
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    • pp.399-405
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    • 2008
  • Development of the paved track is required as a low-maintenance of conventional line. The paved tracks are one of the types of the ballast reinforced tracks those are manufactured by adopting the prepacked concrete technique. The main elements of this tracks are large sleeper, low elastic pad, fastener, cement mortar, geotextile and recycled ballast. Low elastic pad is the most effective element of such tracks on the basis of stress-displacement characteristics, dynamic response and fatigue characteristics. The stiffness of the pad determine the stiffness of the track. Consequently, it is more important in case of concrete track structure such as paved track because application of low elastic pad seriously effect the durability and stability of the track. The main objective of this study is to confirm the reduction of train load, which transfer to roadbed through various pad effects. To achieve this task static, numerical analysis and real scale repeated loading test was performed while load reduction effect of low elastic pad was analyzed by using displacement, stress and strain ratio characteristics of the paved track.

A Study on the Development of Lightweight Seat Cushion Extension Module (경량형 시트 쿠션 익스텐션 모듈 개발에 관한 연구)

  • Jang, Hanseul;Choi, Seongkyu;Park, Sang-Chul;Lim, Heon-pil;Oh, Eu-Ddeum
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.8
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    • pp.200-207
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    • 2016
  • The automotive seat is an important component that moves in sync with the driver and is actively being developed with various new functions. The aim of this work is to develop a lightweight seat cushion extension module using a lightweight material. To this end, a structural strength analysis, vertical strength test, and durability test were conducted. In the structural analysis, the maximum value of deformation under vertical load was 4.98 mm at the front of the upper panel. The maximum stress was approximately 105 MPa, which occurred at the point of contact between the upper and lower panels of the module. The vertical strength test showed a maximum vertical deformation of 5.31 mm under a vertical load, which differed from the analysis results by approximately 6.45%. The structural safety of the product was verified by the fact that it showed no harmful deformation or damage during operation after the vertical strength test and a durability test for 20,000 cycles. Furthermore, the use of engineering plastics made it possible to reduce the weight by approximately 30% compared to existing products. The lack of damage after tests verified the passenger safety, strength, and rigidity of the product. The results are expected to be applied for improving environmental and fuel efficiency regulations and preventing accidents due to driver fatigue. The applications of this module could be expanded various types of vehicles, as well as other industries in which eco-friendly and lightweight materials are used.

A Study of Dynamic Instability for Sigmoid Functionally Graded Material Plates on Elastic Foundation (탄성지반위에 놓인 S형상 점진기능재료(FGM)판의 동적 불안정성에 관한 연구)

  • Lee, Won-Hong;Han, Sung-Cheon;Park, Weon-Tae
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.28 no.1
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    • pp.85-92
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    • 2015
  • This article presents the dynamic instability response of sigmoid functionally graded material plates on elastic foundation using the higher-order shear deformation theory. The higher-order shear deformation theory has ability to capture the quadratic variation of shear strain and consequently shear stress through the plate thickness. The governing equations are then written in the form of Mathieu-Hill equations and then Bolotin's method is employed to determine the instability regions. The boundaries of the instability regions are represented in the dynamic load and excitation frequency plane. The results of dynamic instability analysis of sigmoid functionally graded material plate are presented using the Navier's procedure to illustrate the effect of elastic foundation parameter on dynamic response. The relations between Winkler and Pasternak elastic foundation parameter are discussed by numerical results. Also, the effects of static load factor, power-law index and side-to-thickness ratio on dynamic instability analysis are investigated and discussed. In order to validate the present solutions, the reference solutions are used and discussed. The theoretical development as well as numerical solutions presented herein should serve as reference for the dynamic instability study of S-FGM plates.

A Analytical Study on Seismic Performance of Stainless Water Tank using Lead Rubber Bearing (납고무받침을 이용한 스테인리스 물탱크 내진성능에 관한 해석적 연구)

  • Kim, Hu-Seung;Oh, Ju;Jung, Hie-Young
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.11
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    • pp.230-236
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    • 2018
  • Earthquakes over 5.0 on the Richter scale have recently occurred in Korea, which has led to interest in the seismic safety of structures. If a water storage facility is damaged by an earthquake, the water could leak, and the insufficient water would make fire suppression difficult. Therefore, a water storage facility should satisfy safety requirements for earthquakes. In this study, the seismic performance of a water tank was improved by installing a lead rubber bearing between the foundation and the tank. It designed the lead rubber bearing available to the existed concrete foundation. ANSYS was used for modeling to consider the interaction between the fluid and structure of the tank and the hydrostatic and hydrodynamic pressure using four seismic waves. In the case of hydrostatic pressure at 2.5 water level, full level, the same stress appeared irrespective of whether the seismic isolation was installed. When hydrostatic pressure and hydrodynamic pressures are applied at the same time, the seismic-isolated water tank showed less seismic force, and the damping ratio was lower than that of general seismic isolation. This occurred because the weight of the water tank is much smaller than the stiffness of the seismic isolation. The result is expected to be used for further research on seismic capacity evaluation for water tanks.

Study on the Defect Improvement of Fuel Flow Proportioner Install Structure on Aircraft (항공기 연료흐름분배기 장착 구조물 결함개선 연구)

  • Choi, Hyoung Jun;Lee, Jin Won;Choi, Jae Ho;Park, Sung Jae
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.4
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    • pp.558-567
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    • 2020
  • This study examined the defect characteristics of fuel flow proportioner-mounted structures to analyze the causes of structural defects during aircraft operation. System vibrations and single component vibrations that occur during aircraft operations are usually the cause of structural defects. The fuel flow proportioner causes a defect in the support structure due to the vibration caused by the pressure change caused by the sudden increase in the flow rate. Defects in the support structure of the fuel flow proportioner are not correlated directly with the cracking of the maneuver, and flight time according to aircraft operation analysis is related to the use of A/B. The structural reinforcement configuration was confirmed through static and life analysis of the cracks of the bracket mounted under the fuel flow proportioner for improvement of the defect. An analysis of the reinforcement revealed a minimum structural strength of +0.15. Structural life analysis confirmed that the stress acted on the site under 15Ksi. The fatigue life was confirmed to be more than 7,700 Cycles.

Performance Improvement of Overpass Bridge by Weight Reduction (고가교 경량화에 따른 성능개선)

  • Kim, Sung Bae;Nam, Sang Hyeok;Kim, Jang-Ho Jay
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.2
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    • pp.51-60
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    • 2011
  • In this study, structural safety capacity analysis of the overpass railway bridge between Konkuk Univ. and Guui station railroad has been performed. The overpass is expected to have suffered durability reduction by deterioration. The weight reduction of the overpass has been implemented to prevent further durability reduction and to improve performance capacity. To reduce the weight, 3 procedures of replacing concrete soundproofing wall to light-weight soundproofing wall, replacing gravel ballast to concrete ballast, and reducing the weight of trough have been performed. The analysis of static/dynamic behaviors and improved capacity of the light-weighted overpass bridge has been performed. The structural safety verification of the improved structure has been implemented by using rating factors of load carrying capacity of PSC I girder. The results have shown that the deflection has been reduced by 2.6mm and tensile strength has been improved by 1.07MPa, which indicate that the structural capacity has effectively been improved. Also, the natural frequency has improved by approximately 30% where vibration reduction and dynamic behavior improvement have been achieved. Moreover, in the rating factor evaluation based on analysis and test results, an improvement from 1.82 to 1.93 has been observed. Therefore, weight reduction method for the overpass is effective considering overall results.