• Title, Summary, Keyword: 에너지 소산

Search Result 449, Processing Time 0.031 seconds

A Tensor Invariant Dissipation Equation Accounting for Extra Straining Effects (이차적인 변형률효과를 고려한 텐서 불변성 난류에너지 소산율방정식)

  • 명현국
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.18 no.4
    • /
    • pp.967-976
    • /
    • 1994
  • A tensor invariant model equation for the turbulent energy dissipation rate is proposed in the present study, which is able to simulate secondary straining effects such as curvature effects without the introduction of additional empirical input. The source term in this model has a combined form of the generation term due to the mean vorticity with the conventional one due to the mean strain rate. An extended low-Reynolds-number $k-\epsilon$ turbulence model involving this new model equation is tested for a turbulent Coutte flow between coaxial cylinders with inner cylinder rotated, which is a well defined example of curved flows. The predicted results indicate that the present model works much better for this flow, compared with previous models.

A Study on the Effect of Energy Dissipation in Extruding Clad Rod (복합봉재 압출에 의한 에너지 소산의 영향에 관한 연구)

  • Kim, Chang-Hoon
    • Journal of the Korean Society of Manufacturing Process Engineers
    • /
    • v.5 no.2
    • /
    • pp.56-64
    • /
    • 2006
  • Rapid progress in many branches of technology has led to a demand on new materials such as high strength light weight alloys, powdered alloys and composite materials. The hydrostatic extrusion is essentially a method of extruding a clad rod through a die. In order to investigate the effect of the process conditions such as friction heat, deformation and clad thickness on the clad extrusion process, viscoplastic finite element simulations were conducted. A specific model for theoretical analysis used in this study is The single scalar variable version of Hart's model. An experiment also has been carried out using 1.5MN hydrostatic extruder with variable speed ram, LVDT and load cell for comparison. It is found that the hydrostatic extrusion pressure considering the effect of heat dissipation in this theoretical work was closer to the experimental pressure than the isothermal hydrostatic extrusion pressure.

  • PDF

Experimental Test for Seismic Performance of PCS Structural System (PCS 구조 시스템의 내진 성능 분석)

  • Park, Soon-Kyu;Yeo, In-Seok
    • Journal of the Korea Concrete Institute
    • /
    • v.19 no.3
    • /
    • pp.313-322
    • /
    • 2007
  • The PCS system, which consists of precast concrete column and steel beam, is a kind of composite structural systems. In this paper, experimental study has been conducted to analyze seismic performance of bolted beam-to-column connections for the PCS system. Based on experimental results from the seismic testing of eight interior PCS specimens, it shows that behavior of PCS system is satisfactory to seismic performance criteria of ACI such as strength deterioration, stiffness degradation and energy dissipation capacity except initial stiffness. All of the specimens maintain their strength at large levels of story drift without significant loss of stiffness and show high ductility level for inelastic behavior. The energy dissipation capacity is two times greater than requirement of ACI criterion. But the initial stiffness of all specimens does not satisfy ACI criterion, and this phenomenon is similar to the other composite structural systems such as RCS, CFT system.

Structural Capacity of Steel Plate Walls According to Various Infill Plate Details (다양한 웨브강판 상세에 따른 골조강판벽의 구조성능)

  • Park, Hong Gun;Choi, In Rak;Jeon, Sang Woo;Kim, Won Ki
    • Journal of Korean Society of Steel Construction
    • /
    • v.19 no.1
    • /
    • pp.67-78
    • /
    • 2007
  • In this study, we performed an investigation on the variations in the structural capacity of steel plate walls with various infill plate details. Five three-story plate walls with thin web plates were tested. Parameters for the test specimens were the connection details between the moment frame and infill plates, such as weld and bolt connections, the location and length of weld connection, and coupling wall. Regardless of the details of infilled steel plate, the steel plate wall specimens showed excellent initial stiffness, strength, and energy dissipation capacity. However, the wall with bolt-connected infill plates showed slightly low deformation capacity. This result showed that for workability and cost efficiency,various wall details can be used in practice without causing a significant decrease in the structural capacity of steel plate walls. A method for making projections on strength and energy dissipation capacity of steel plate wall specimens with various details was developed.

Experimental Study on the Vibration Control Capacity of Hybrid Buckling-Restrained Braces (하이브리드 비좌굴가새의 진동제어능력에 관한 실험적 연구)

  • Kim, Do Hyun;Ju, Young Kyu;Kim, Myung Han;Sung, Woo Gi;Kim, Sang Dae
    • Journal of Korean Society of Steel Construction
    • /
    • v.21 no.1
    • /
    • pp.83-91
    • /
    • 2009
  • Buckling Restrained Braces (BRBs) show good seismic behavior. They do not dissipate energy, however, when they are subjected to minor earthquakes or wind. Hybrid Buckling Restrained Braces (H-BRBs), which can improve the wind performance of the BRB system, are a kind of hybrid damper system composed of a viscoelastic damper and BRBs. In this paper, two H-BRB specimens with different cores were experimentally investigated to ensure the structural behavior of the H-BRB system in an elastic range. The axial deformation of the primary resisting system was compared with that of the secondary resisting system, and the equivalent damping ratio of the H-BRBs was estimated. It was concluded that H-BRBs with double shear dampers show good structural behavior and are applicable to tall buildings, to improve the building performance at a comfortable level.

Dependency Evaluation According to Damper Strut Type (댐퍼 스트럿 형상에 따른 의존성 평가)

  • Lee, Hyun-Ho
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.18 no.5
    • /
    • pp.78-86
    • /
    • 2014
  • The purpose of this study is the displacement and velocity dependence evaluation of I type and S type metallic dampers. For this purpose, 12 metallic damper specimens are prepared and dependence test are performed. Test variables are strut type, displacement and velocity dependence. From the evaluation results of dependence tests, number of cycles are fully exceeded than minimum 5 cycles described in ASCE 7-10. According to displacement dependence test results, larger target displacement (50mm) shows lower cyclic numbers and cumulated energy dissipated area than lower target displacement (25mm). Also it show higher strength and early failure than short target displacement. In velocity dependence evaluation, fast target velocity (60mm/sec) shows lower cyclic numbers and cumulated energy dissipated area than target velocity (40mm/sec). As a results of basic properties, dependence evaluation and cumulated energy dissipated area evaluation, dependence capacity of S type metallic damper is far superior than I type.

Displacement and Velocity Dependence of Clamped Shape Metallic Dampers (꺽쇠형 강재 댐퍼의 변위 및 속도 의존성)

  • Lee, Hyun Ho
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.17 no.2
    • /
    • pp.62-70
    • /
    • 2013
  • The purpose of this study is the displacement and velocity dependence evaluation of clamped shape metallic damper, which were evaluated superior in energy dissipation capacity than straight type slit damper. For this purpose, 6 metallic damper specimens are prepared and dependence test are performed. Test variables are displacement dependence and velocity dependence. According to displacement dependence test results, larger target displacement (50mm) shows lower cyclic numbers and cumulated energy dissipated area than lower target displacement (25mm). Also it shows higher strength and early failure than short target displacement. In velocity dependence evaluation, fast target velocity (60mm/sec) shows lower cyclic numbers and cumulated energy dissipated area than slow target velocity (40mm/sec). Therefore the hysteresis dependence of metallic damper were evaluated as close relation to the loading displacement and velocity conditions.

Effects of Design Parameters on Structural Performance of Precast Piers with Bonded Prestressing Steels (부착 긴장재를 가진 조립식 교각 설계변수의 구조성능에 미치는 영향)

  • Shim, Chang-Su;Yoon, Jae-Young
    • Journal of The Korean Society of Civil Engineers
    • /
    • v.30 no.1A
    • /
    • pp.15-26
    • /
    • 2010
  • Quasi-static tests were conducted to evaluate structural performance of precast piers prestressed by bonded prestressing steels. Combinations of prestressing bars and normal reinforcing bars, embedded steel tubes and prestressing strands were used as continuous steels crossing the joints of a precast pier. Main design parameters were steel ratio, magnitude of prestress force, and section details. Flexural strength and energy dissipation capacity of precast columns with higher steel ratio showed better performance due to continuous steels after opening of the joints. Precast piers with embedded members showed stable behavior after reaching maximum loads resulting in higher displacement ductility and energy dissipation capacity increased as the introduced prestress increased. Self-centering behavior at early stages and stress increase of confining reinforcements were observed from highly prestressed columns. Combination of prestressing steels and normal reinforcing bars should be used in design to prevent rapid strength degradation after reaching the maximum load.

Collision Analysis of Submerged Floating Tunnel by Underwater Navigating Vessel (수중운항체에 대한 해중터널의 충돌해석)

  • Hong, Kwan-Young;Lee, Gye-Hee
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.27 no.5
    • /
    • pp.369-377
    • /
    • 2014
  • In this paper, to recognize the collision behavior between a submerged floating tunnel(SFT) and underwater navigation vessel(UNV), both structures are modeled and analyzed. The SFT of collision point is modeled tubular section using concrete with steel lining. The other part of SFT is modeled elastic beam elements. Mooring lines are modeled as cable elements with tension. The under water navigation vessel is assumed 1800DT submarine and its total mass at collision is obtained with hydrodynamic added mass. The buoyancy force on SFT is included in initial condition using dynamic relaxation method. The buoyancy ratio (B/W) and the collision speed are considered as the collision conditions. As results, energy dissipation is concentrated on the SFT and that of the UNV is minor. Additionally, the collision behaviors are greatly affected by B/W and the tension of mooring lines. Especially, the collision forces are shown different tendency compare to vessel collision force of current design code.

Experimental Study on the Cyclic Behavior of Modular Building with Strap Braced Load Bearing Steel Stud Walls (스트랩 브레이스를 갖는 내력벽식 모듈러건축 스틸스터드 벽체의 반복하중에 대한 거동 연구)

  • Lee, Doo Yong;Cho, Bong Ho;Kim, Tae Hyeong;Ha, Tae Hyu
    • Journal of Korean Society of Steel Construction
    • /
    • v.28 no.6
    • /
    • pp.415-425
    • /
    • 2016
  • Load-bearing steel stud wall system is widely used for the middle-to-high rise modular buildings worldwide. Seismic performance is a key issue to apply load-bearing steel stud wall system to modular buildings in Korea. This study proposes a new strap braced steel stud wall system with enhanced seismic performance and design equations considering the flexural behaviour of the vertical outer studs. For the verification, two specimens with different strap braces and vertical outer stud were designed and tested. The test results showed that the total strengths were evaluated to be 1.11 to 1.18 times higher than the predicted values. Usually strap braced walls are considered to have low energy dissipation capacities. The proposed system showed enhanced seismic performance with equivalent damping of 9.42% due to the reduced pinching effects.