• Title/Summary/Keyword: structural safety

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Structural Safety of Lightweight Valve Disc by Topology Optimization Design based on Computational Simulation (전산 시뮬레이션 기반의 위상최적설계에 의한 경량 밸브디스크의 구조적 안전성)

  • Kim, Taehyung
    • Journal of Energy Engineering
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    • v.29 no.3
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    • pp.25-33
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    • 2020
  • In this study, flow and structural computational analysis were performed to investigate the structural safety of the lightweight butterfly valve disc designed by topology optimization. After flow analysis, as the opening angle increased, the flow coefficient increased non-linearly and showed a gentle slop. When the opening angle was 12 degree, the cavitation could be predicted. After FE analysis, all FE von-Misses stresses of the lightweight disc were smaller than the yield strength of the material, and all FE maximum deformations were also smaller than the conservative deformation of the previous study. Ultimately, it was confirmed that the structural safety of the lightweight valve disc based on computational analysis is effective.

Investigation of Structural Safety of Monobloc Tubular Drive Shaft Subjected to Torque (비틀림 모멘트가 부가되는 일체형 중공 드라이브 샤프트의 구조 안정성 분석)

  • Guk, Dae-Sun;Ahn, Dong-Gyu;Lee, Ho-Jin;Jung, Jong-Hoon
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.12
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    • pp.1073-1080
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    • 2015
  • A drive shaft is used to transmit torque and rotation through the connection of components of a drive train. Recently, a monobloc drive shaft without welding regions is developed to improve the safety of the drive shaft. The drive shaft bears the shear stress induced by torque. The objective of this paper is to investigate into the structural safety of a monobloc tubular drive shaft subjected to torque. Elasto-plastic finite element (FE) analysis is performed to estimate the deformation behavior of the drive shaft and stress-strain distribution in the drive shaft. Several techniques are used to create finite element (FE) model of the monobloc tubular drive shaft subjected to torque. Through the comparison of the results of FE analyses with those of experiments from the viewpoint of rotational angle, appropriate correction coefficients for different load conditions are estimated. The safety of the tubular drive shaft is examined using the results of FE analyses for different load conditions. Finally, it is noted that the designed tubular drive shaft has a sufficient structural safety.

A Study on the Structural Safety of the Roof Improvement Project (슬레이트지붕 개량사업 구조안전성 검토)

  • Kang, Kyung-Soo
    • Journal of the Korean Institute of Rural Architecture
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    • v.20 no.1
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    • pp.19-26
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    • 2018
  • The roof improvement project is being carried out under the government's leadership for the sake of national welfare. The project is to replace the asbestos slate roof with a metallic one. In this study, the structural safety of the improved roof was examined and the project guidelines were reviewed. The causes of the roof damage were investigated and the structural analysis was performed for the roof frame subject to wind and snow loads. Metallic roof assemblies have higher strength and load resistance capability than usual slate ones, so the structural safety is governed by the frame. The stresses of the roof frame elements caused by the wind and snow loads were analyzed according to roof frame with various spacings between the rafters and the purlins. Wind load analysis was performed by 24, 28, and 38 m/sec of the basic wind speed. Snow load analysis was carried out by 0.5, 1.0 and $2.0kN/m^2$ of the ground snow load. As the analysis result, the current spacing and the size of the lumber did not satisfy the Korean building code specification. To secure the safety of the roof improvement project, the spacing of the roof frame elements and the size of the lumber should be determined based on the analysis results by structural engineers.

In-structure Response Evaluation of Shear Wall Structure via Shaking Table Tests (진동대 실험을 통한 전단벽 구조물의 층응답 특성 평가)

  • Jung, Jae-Wook;Ha, Jeong-Gon;Hahm, Daegi;Kim, Min Kyu
    • Journal of the Earthquake Engineering Society of Korea
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    • v.25 no.3
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    • pp.129-135
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    • 2021
  • After the manual shutdown of the Wolseong nuclear power plant due to an earthquake in Gyeongju in 2016, anxiety about the earthquake safety of nuclear power plants has become a major social issue. The shear wall structure used as a major structural element in nuclear power plants is widely used as a major structural member because of its high resistance to horizontal loads such as earthquakes. However, due to the complexity of the structure, it is challenging to predict the dynamic characteristics of the structure. In this study, a three-story shear wall structure is fabricated, and the in-structure response characteristics of the shear wall structure are evaluated through shaking table tests. The test is performed using the Gyeongju earthquake that occurred in 2016, and the response characteristics due to the domestic earthquake are evaluated.

Investigation of the Performance Based Structural Safety Factor of Elbows in Nuclear Power Plants (원전 엘보우의 성능기반 안전여유도 분석)

  • Lee, Sung-Ho;Park, Chi-Yong;Park, Jai-Hak
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.8
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    • pp.826-831
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    • 2009
  • The piping systems in nuclear power plant are composed of various typed pipes such as straight, elbow pipe, branch and reducer etc. The elbow is connected from straight pipe to another pipes in order to establish the complicated piping system. Elbow is one of very important components considering management of wall thinning degradation. It is however applied by various loads such as system pressure, earthquake, postulated break loading and many transient loads, which provoke simply the internal pressure, bending and torsional stress. In this study, firstly pipes in the secondary system of the nuclear power plant are classified as pipe size and type for selecting the investigating range. Next, a large number of finite element analysis considering the all typed dimensions of commercial pipe has been performed to find out the behavior of TES(twice elastic slop) plastic load of elbows, which is based on evaluation of the structural safety factor. Finally performance based structural safety factor was investigated comparing with maximum allowable load by construction code.

Design of Anti-Surge Valve for FPSO Fuel Gas Compressor System (FPSO용 연료가스압축 시스템을 위한 서지방지 밸브 설계)

  • Park, Hyung-Wook;Cho, Jong-Rae;Lee, Seung-Min;Park, Jong-Jin
    • Journal of Advanced Marine Engineering and Technology
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    • v.35 no.4
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    • pp.443-450
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    • 2011
  • Fuel gas compressor system is applied to medium FPSO. In order to avoid surge, this system used the anti-surge valves. When surge occurs it may lead to system's fracture. So anti-surge valves are evaluated structural strength and structural safety. Especially, in emergency mode, valves are must be guaranteed structural safety. In this study, structural strength and structural safety of anti-surge valve was evaluated using the numerical simulation. Unigraphics NX 4.0 was used as Geometrical models, structural strength and structural safety calculation were carried out by ANSYS Workbench 12.1. The ASME Boiler & Pressure Vessel Code is refer to allowable strength and safety factor of the valves.

Structural safety reliability of concrete buildings of HTR-PM in accidental double-ended break of hot gas ducts

  • Guo, Quanquan;Wang, Shaoxu;Chen, Shenggang;Sun, Yunlong
    • Nuclear Engineering and Technology
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    • v.52 no.5
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    • pp.1051-1065
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    • 2020
  • Safety analysis of nuclear power plant (NPP) especially in accident conditions is a basic and necessary issue for applications and commercialization of reactors. Many previous researches and development works have been conducted. However, most achievements focused on the safety reliability of primary pressure system vessels. Few literatures studied the structural safety of huge concrete structures surrounding primary pressure system, especially for the fourth generation NPP which allows existing of through cracks. In this paper, structural safety reliability of concrete structures of HTR-PM in accidental double-ended break of hot gas ducts was studied by Exceedance Probability Method. It was calculated by Monte Carlo approaches applying numerical simulations by Abaqus. Damage parameters were proposed and used to define the property of concrete, which can perfectly describe the crack state of concrete structures. Calculation results indicated that functional failure determined by deterministic safety analysis was decided by the crack resistance capability of containment buildings, whereas the bearing capacity of concrete structures possess a high safety margin. The failure probability of concrete structures during an accident of double-ended break of hot gas ducts will be 31.18%. Adding the consideration the contingency occurrence probability of the accident, probability of functional failure is sufficiently low.

A Study on Structural Safety Management Plan for Above Ground and Underground Structure Dismantling work (지상 및 지하구조물 해체공사를 위한 구조 안전관리 방안 연구)

  • Shim, Hak-Bo;Jeon, Hyun-Soo;Seok, Won-Kyun
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2021.11a
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    • pp.194-195
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    • 2021
  • Due to urban regeneration projects or changes in the living environment, there is an increasing need to demolish old buildings that have lost their functions. Demolition of above ground and underground structures is an important construction project that greatly affects the construction period and safety of the entire process. However, it is difficult for the safety officer to manage the demolition work due to the lack of specific and diverse data applicable to the site of the demolition plan. Therefore, in this study, items that need to be improved in structural safety when the above-ground and underground structures are demolished are reviewed and organized. For the main contents of structural safety management in demolition work, 1) structural review reflecting the order of demolition work, 2) installation and dismantling of steel pipe scaffolding and dust nets, 3) installation and dismantling of system scaffolding, 4) installation and dismantling of fall prevention nets, 5) jack support Installation and dismantling, 6) movement of equipment, movement and planning between floors, 7) equipment for demolition of structures, height of remnants, 8) site cleanup, and 9) equipment operators were categorized and arranged.

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Analysis of 3D Laser Scanner Input Performance in Structual Safety Diagnosis (구조안전진단에서의 3D 레이저 스캐너 투입 성과 분석)

  • Seong, Do-Yun;Baek, In-Soo;Kim, Jea-Jun;Ham, Nam-Hyuk
    • Journal of KIBIM
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    • v.11 no.3
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    • pp.34-44
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    • 2021
  • This study quantitatively analyzes the work performance of the structural safety diagnosis team that diagnoses pipe racks. To this end, a method for evaluating the performance of the structural safety diagnosis team using the queuing model was proposed. For verification, the case of applying the existing method and the method of introducing a 3D laser scanner for one site was used. The period, number of people, and initial investment cost of each project were collected through interviews with case project experts. As a result of analyzing the performance of the structural safety diagnosis team using the queuing model, it was possible to confirm the probability of delay in the work of each project and the amount of delayed work. Through this, the cost (standby cost) when the project was delayed was analyzed. Finally, economic analysis was conducted in consideration of the waiting cost, labor cost, and initial investment cost. The results of this study can be used to decide whether to introduce 3D laser scanners.

Wind Pressure Analysis of Movable Shading Using CFD (CFD 해석을 이용한 가변 차양 장치의 풍압력 분석)

  • Kim, Gee-Chul;Lee, Joon-Ho;Baik, Yong-Kyu
    • Journal of Korean Association for Spatial Structures
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    • v.19 no.2
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    • pp.83-90
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    • 2019
  • Most of the variable shading devices are installed outdoors, so they are greatly affected by structural safety due to external climate change, wind, rain, and snow. Especially, due to strong wind such as typhoons, safety problems may occur due to the dropout of the device. Therefore, it is necessary to secure the structural safety against the wind. Therefore, it is necessary to analyze the structural behavior of the windshield to evaluate the structural safety of the variable sunshade device. In this study, we analyze the wind pressure applied to the shading material according to the change of the length of the variable shading device, and apply it to the calculation of the wind load for the structural design of the variable shading device. The CFD (Computational Fluid Dynamic) analysis of the structure of the sample was used to analyze wind pressure magnitude and distribution. In order to estimate the wind pressure, the maximum wind loads of the static and negative pressures acting on the structure were analyzed from numerical simulation results.