• Title/Summary/Keyword: structural adequacy

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Nonlinear Aseismic Analysis of Spent Fuel Storage Racks(I) (핵폐기물 저장설비의 비선형 내진해석(I))

  • Lee, Chong-Dong;Chang, Jae-Wan;Yoo, Bong
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1993.04a
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    • pp.191-198
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    • 1993
  • This paper presents the analysis briefs to evaluate the structural adequacy of the KMRR spent fuel storage racks which stack modules in three layers. The seismic analysis models are idealized to consider the overall dynamic motions such as rocking, sliding and liftoff in the event of an postulated earthquake. The displacement time histories of the floor obtained from the floor response spectra in three orthogonal directions are simultaneously applied to the nonlinear seismic model of the structure with gap and friction elements.

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Structural Strength Assessment of Forward Cargo Hold for Kamsarmax CSR Bulk Carrier (Kamsarmax급 CSR Bulk Carrier의 Forward Cargo Hold 구조적 특성 및 안정성 검증)

  • Hwang, Sang-Wook;Park, Jeong-Jun
    • Special Issue of the Society of Naval Architects of Korea
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    • 2011.09a
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    • pp.17-20
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    • 2011
  • The International Association of Classification Societies (IACS) had developed the Common Structural Rules (CSR) for bulk carriers as per the needs noted above. ISO and IMO GBS (Goal-Based Standards) are now being developed in this regard. This study has been prepared to verity the strength of forward cargo hold of 82,000 DWT class bulk carriers. A cargo hold/tank 3-D FE model was established to assess the structural adequacy of the primary structural members with the loading conditions. Full breadth model was established for the analysis considering asymmetric nature of structural layout and loading conditions. To summarize this result of structural assessment based on IACS CRS for bulk carrier, it is benefit to design this kind of bulk carriers and to study the strength assessment for the similar type of bulk carriers.

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Structural Equation Modeling for Career Satisfaction, Career Commitment and Career Withdrawal Intention in Clinical Nurses (임상간호사의 경력만족, 경력몰입 및 경력변경의도에 대한 구조모형)

  • Choi, Hyun Ju
    • Journal of Korean Clinical Nursing Research
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    • v.20 no.2
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    • pp.236-245
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    • 2014
  • Purpose: Preventing frequent change and discontinuation of the nurses' carrier is one of major issues for human resource management in a health organization (HO). This study was conducted to get evidences for improvement nursing manpower management and career development of the clinical nurses through investigating affecting factors to their career withdrawal intention (CWI). Methods: A self-report questionnaire survey was conducted on the subjects of the 590 clinical nurses with more than one year tenure from the eight hospitals in Busan city during December, 2013. Data analysis was performed using SPSS program (ver 20.0) and AMOS program (ver 20.0) for structural modeling. Results: Career satisfaction (CS) showed positive(+) effects, and increased with higher job adequacy (${\beta}=.139$, t=2.676, p=.007), job autonomy (${\beta}=.260$, t=4.815, p<.001), and career planning (${\beta}=.301$, t=5.797, p<.001). Career commitment (CC) showed positive(+) effects, and increased with higher job adequacy (${\beta}=.107$, t=2.280, p=.023), job autonomy (${\beta}=.257$, t=5.035, p<.001), career planning (${\beta}=.232$, t=4.717, p<.001), and career satisfaction (CS)(${\beta}=.123$, t=2.293, p=.022). CWI showed negative(-) effects and increased with lower CC (${\beta}=-.906$, t=-15.72, p<.001). Conclusion: Results indicate that CC and CS have important mediating roles between job adequacy, job autonomy, career planning and CWI. As CC directly influenced CWI, there is a need to strengthen CC to prevent frequent changes and discontinuation of nurses' careers and to contribute to productivity HO's.

Exchange Rate Volatility Measures and GARCH Model Applications : Practical Information Processing Approach (환율 변동성 측정과 GARCH모형의 적용 : 실용정보처리접근법)

  • Moon, Chang-Kuen
    • International Commerce and Information Review
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    • v.12 no.1
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    • pp.99-121
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    • 2010
  • This paper reviews the categories and properties of risk measures, analyzes the classes and structural equations of volatility forecasting models, and presents the practical methodologies and their expansion methods of estimating and forecasting the volatilities of exchange rates using Excel spreadsheet modeling. We apply the GARCH(1,1) model to the Korean won(KRW) denominated daily and monthly exchange rates of USD, JPY, EUR, GBP, CAD and CNY during the periods from January 4, 1998 to December 31, 2009, make the estimates of long-run variances in the returns of exchange rate calculated as the step-by-step change rate, and test the adequacy of estimated GARCH(1,1) model using the Box-Pierce-Ljung statistics Q and chi-square test-statistics. We demonstrate the adequacy of GARCH(1,1) model in estimating and forecasting the volatility of exchange rates in the monthly series except the semi-variance GARCH(1,1) applied to KRW/JPY100 rate. But we reject the adequacy of GARCH(1,1) model in estimating and forecasting the volatility of exchange rates in the daily series because of the very high Box-Pierce-Ljung statistics in the respective time lags resulting to the self-autocorrelation. In conclusion, the GARCH(1,1) model provides for the easy and helpful tools to forecast the exchange rate volatilities and may become the powerful methodology to overcome the application difficulties with the spreadsheet modeling.

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Development of Analytical Model to Predict The Inelastic Behavior of Reinforced Concrete And Masonry Structures (RC 및 조적조구조물의 비탄성 거동예측을 위한 해석적 모델개발)

  • 홍원기;이호범;변근주
    • Proceedings of the Korea Concrete Institute Conference
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    • 1993.04a
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    • pp.160-167
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    • 1993
  • In earthquake structural engineering towards a better understanding of both the earthquake ground motion and structural response, the design of concrete structures to resist strong ground input motions is not a simple matter, and analytical models for such structures must be developed from a design perspective that accounts for the complexities of the structural responses. The primary objective earthquake structural engineering research is to ensure the safety of structures by understanding and improving a design menthodology. Ideally, this would require the development of an analytical model related to a design methodology that ensures a dectile performance. For the accurate assessment of the adequacy of analytically developed model, experiments conducted to study the inplane inelastic cyclic behavior of structures should verify the analytical approach. The paper is to demonstrate experimentally verified analytical method that provide the adequate degree of safety and confidience in the behavior of R.C. structural components and further attempts to extend the developed modeling technique for use by practicing structural engineers.

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Seismic response modification factors for stiffness degrading soil-structure systems

  • Ganjavi, Behnoud;Bararnia, Majid;Hajirasouliha, Iman
    • Structural Engineering and Mechanics
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    • v.68 no.2
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    • pp.159-170
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    • 2018
  • This paper aims to develop response modification factors for stiffness degrading structures by incorporating soil-structure interaction effects. A comprehensive parametric study is conducted to investigate the effects of key SSI parameters, natural period of vibration, ductility demand and hysteretic behavior on the response modification factor of soil-structure systems. The nonlinear dynamic response of 6300 soil-structure systems are studied under two ensembles of accelograms including 20 recorded and 7 synthetic ground motions. It is concluded that neglecting the stiffness degradation of structures can results in up to 22% underestimation of inelastic strength demands in soil-structure systems, leading to an unexpected high level of ductility demand in the structures located on soft soil. Nonlinear regression analyses are then performed to derive a simplified expression for estimating ductility-dependent response modification factors for stiffness degrading soil-structure systems. The adequacy of the proposed expression is investigated through sensitivity analyses on nonlinear soil-structure systems under seven synthetic spectrum compatible earthquake ground motions. A good agreement is observed between the results of the predicted and the target ductility demands, demonstrating the adequacy of the expression proposed in this study to estimate the inelastic demands of SSI systems with stiffness degrading structures. It is observed that the maximum differences between the target and average target ductility demands was 15%, which is considered acceptable for practical design purposes.

Assessment of collapse safety margin for DDBD and FBD-designed RC frame buildings

  • Alimohammadi, Dariush;Abadi, Esmaeel Izadi Zaman
    • Structural Engineering and Mechanics
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    • v.83 no.2
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    • pp.229-244
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    • 2022
  • This paper investigates the seismic performance of buildings designed using DDBD (Direct Displacement based Design) and FBD (Force based Design) approaches from the probabilistic viewpoint. It aims to estimate the collapse capacity of structures and assess the adequacy of seismic design codes. In this regard, (i) IDA (Incremental Dynamic Analysis) curves, (ii) interstory drift demand distribution curves, (iii) fragility curves, and (iv) the methodology provided by FEMA P-695 are applied to examine two groups of RC moment resistant frame buildings: 8-story structures with different plans, to study the effect of different span arrangements; and 3-, 7- and 12-story structures with a fixed plan, to study the dynamic behavior of the buildings. Structural modeling is performed in OpenSees software and validated using the results of an experimental model. It is concluded that increasing the building height would not significantly affect the response estimation of IDA and fragility curves of DDBD-designed structures, while the change in span arrangements is effective in estimating responses. In the investigation of the code adequacy, unlike the FBD approach, the DDBD can satisfy the performance criteria presented in FEMA P-695 and hence provide excellent performance.

An investigation into adequacy of separation gap to preclude earthquake-induced pounding

  • Yazan Jaradat;Pejman Sobhi and Harry Far
    • Structural Engineering and Mechanics
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    • v.86 no.1
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    • pp.29-48
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    • 2023
  • Pounding happens when contiguous structures with differing heights vibrate out of line caused by a seismic activity. The situation is aggravated due to the insufficient separation gap between the structures which can lead to the crashing of the buildings or total collapse of an edifice. Countries around the world have compiled building standards to address the pounding issue. One of the strategies recommended is the introduction of the separation gap between structures. AS1170.4-2007 is an Australian standard that requires 1% of the building height as a minimum separation gap between buildings to preclude pounding. This article presents experimental and numerical tests to determine the adequacy of this specification to prevent the occurrence of seismic pounding between steel frame structures under near-field and far-field earthquakes. The results indicated that the recommended minimum separation gap based on the Australian Standard is inaccurate if low-rise structure in a coupled case is utilised under both near and far field earthquakes. The standard is adequate if a tall building is involved but only when a far-field earthquake happens. The research likewise presents results derived by using the ABS and SRSS methods.

Performance comparison of shear walls with openings designed using elastic stress and genetic evolutionary structural optimization methods

  • Zhang, Hu Z.;Liu, Xia;Yi, Wei J.;Deng, Yao H.
    • Structural Engineering and Mechanics
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    • v.65 no.3
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    • pp.303-314
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    • 2018
  • Shear walls are a typical member under a complex stress state and have complicated mechanical properties and failure modes. The separated-elements model Genetic Evolutionary Structural Optimization (GESO), which is a combination of an elastic-plastic stress method and an optimization method, has been introduced in the literature for designing such members. Although the separated-elements model GESO method is well recognized due to its stability, feasibility, and economy, its adequacy has not been experimentally verified. This paper seeks to validate the adequacy of the separated-elements model GESO method against experimental data and demonstrate its feasibility and advantages over the traditional elastic stress method. Two types of reinforced concrete shear wall specimens, which had the location of an opening in the middle bottom and the center region, respectively, were utilized for this study. For each type, two specimens were designed using the separated-elements model GESO method and elastic stress method, respectively. All specimens were subjected to a constant vertical load and an incremental lateral load until failure. Test results indicated that the ultimate bearing capacity, failure modes, and main crack types of the shear walls designed using the two methods were similar, but the ductility indexes including the stiffness degradation, deformability, reinforcement yielding, and crack development of the specimens designed using the separated-elements model GESO method were superior to those using the elastic stress method. Additionally, the shear walls designed using the separated-elements model GESO method, had a reinforcement layout which could closely resist the actual critical stress, and thus a reduced amount of steel bars were required for such shear walls.

Strength Evaluation of the Cylinder Cover Stud for Low-Speed Marine Diesel Engine (대형엔진 실린더 커버 스터드의 강도 평가)

  • Kim, Byung-Joo;Lee, Jae-Ock;Park, Jin-Soo;Kim, Se-Lak
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.554-559
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    • 2007
  • The cylinder cover stud for assembling the combustion chamber components of low-speed marine diesel engine is one of the main structural components in engine. To understand the structural behavior of the stud is quite important for safe and economic design of it. In this paper, the structural behavior and design adequacy of the stud have been evaluated through strain measurement and structural analysis for the world's two largest engine types. Moreover, a feasibility study for design modification was carried out based on fatigue test and calculation. The results showed that 1) the stud experiences very high stress ratio under normal operating conditions, 2) the fatigue strength of the stud is sufficient, and 3) results from strain measurement and structural analysis were quite close each other.

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