• Title/Summary/Keyword: structural safety

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A Gaussian process-based response surface method for structural reliability analysis

  • Su, Guoshao;Jiang, Jianqing;Yu, Bo;Xiao, Yilong
    • Structural Engineering and Mechanics
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    • v.56 no.4
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    • pp.549-567
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    • 2015
  • A first-order moment method (FORM) reliability analysis is commonly used for structural stability analysis. It requires the values and partial derivatives of the performance to function with respect to the random variables for the design. These calculations can be cumbersome when the performance functions are implicit. A Gaussian process (GP)-based response surface is adopted in this study to approximate the limit state function. By using a trained GP model, a large number of values and partial derivatives of the performance functions can be obtained for conventional reliability analysis with a FORM, thereby reducing the number of stability analysis calculations. This dynamic renewed knowledge source can provide great assistance in improving the predictive capacity of GP during the iterative process, particularly from the view of machine learning. An iterative algorithm is therefore proposed to improve the precision of GP approximation around the design point by constantly adding new design points to the initial training set. Examples are provided to illustrate the GP-based response surface for both structural and non-structural reliability analyses. The results show that the proposed approach is applicable to structural reliability analyses that involve implicit performance functions and structural response evaluations that entail time-consuming finite element analyses.

Structural Safety of Single-Span Greenhouses under Wind Load of Costal Reclaimed Lands (간척지 내 단동형 온실의 풍하중에 대한 구조 안정성 분석)

  • Hong, Se-Woon;Kim, Rack-Woo;Choi, Won
    • Journal of The Korean Society of Agricultural Engineers
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    • v.59 no.4
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    • pp.109-117
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    • 2017
  • Coastal reclamation has created large flat lands, part of which is an attractive site to construct greenhouse complexes for the horticulture industry. Wind environments over these coastal lands are entirely different from those of the inland area, and demand increased structural safety. The objective of this study is to evaluate the structural safety of two single-span greenhouses, peach type and even-span type, under the wind characteristics of coastal reclaimed lands. The wind pressure coefficients acting on the walls and roofs of two greenhouses were measured by wind tunnel experiments, and those acting on the roofs were approximately two times larger than those suggested by the existing design guidelines. Consequently, structural analysis conducted by SAP2000 showed that greenhouse structures designed by the existing guidelines might lead to structural failure under coastal wind conditions because their maximum allowable wind speeds were lower than the design wind speed. Especially, the peach type greenhouse constructed in a reclaimed land could be damaged by approximately 48 % of the design wind speed and needed improvement of structural designs. This study suggested increasing the spacing of rafters with thicker pipes for the peach type greenhouse to enhance economic feasibility of the building under strong wind conditions of reclaimed lands.

Three-dimensional finite element static analysis and safety evaluation of attachable roadside barriers on bridges (탈·부착식 교량 방호울타리의 3차원 유한요소 정적해석 및 안전성 평가)

  • Lee, Sang-Youl
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.4
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    • pp.2414-2418
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    • 2014
  • This study carried out three-dimensional finite element analysis and structural safety evaluation of attachable roadside barriers. The effects of diaphragm distance and the number of bolts on displacements and maximum stresses for various parameters are studied using the LS-DYNA finite element program for this study. In this study, the existing finite element analysis of barriers using the LS-DYNA program is further extended to study static behaviors and structural safety of the barrier with module structures connected by anchor bolt inserted through concrete bridge decks. The numerical results for six parameters are verified by comparing different models with displacements and stress distribution occurred in the barrier and shows good structural performance.

Effect of seismic design level on safety against progressive collapse of concentrically braced frames

  • Rezvani, Farshad Hashemi;Asgarian, Behrouz
    • Steel and Composite Structures
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    • v.16 no.2
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    • pp.135-156
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    • 2014
  • In this research the effect of seismic design level as a practical approach for progressive collapse mitigation and reaching desired structural safety against it in seismically designed concentric braced frame buildings was investigated. It was achieved by performing preliminary and advanced progressive collapse analysis of several split-X braced frame buildings, designed for each seismic zone according to UBC 97 and by applying various Seismic Load Factors (SLFs). The outer frames of such structures were studied for collapse progression while losing one column and connected brace in the first story. Preliminary analysis results showed the necessity of performing advanced element loss analysis, consisting of Vertical Incremental Dynamic Analysis (VIDA) and Performance-Based Analysis (PBA), in order to compute the progressive collapse safety of the structures while increasing SLF for each seismic zone. In addition, by sensitivity analysis it became possible to introduce the equation of structural safety against progressive collapse for concentrically braced frames as a function of SLF for each seismic zone. Finally, the equation of progressive collapse safety as a function of bracing member capacity was presented.

An Experimental Study on Structural Safety Assesment of Wet Type Floor Heating System with Insulation (완충재 적용에 따른 습식온돌의 구조안전성 평가를 위한 실험연구)

  • Ahn, Jae-Won;Jun, Myoung-Hoon;Lee, Bum-Sik;Lee, Do-Heun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.287-290
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    • 2005
  • Housing is demanded to convert simple dwelling space into delightful one by improving of standard of living by economic development It is interested in the impact noise of the apartment housing that is revised to housing construction criteria at 29 March 2005 and then regulated the level of floor impact noise by the rule. The plan, which is actively investigated by counterplan for the reduction of impact noise, is application of sound insulation. In generally, first target by using insulation is the reduction of floor thermal transmittance in floor heating system of apartment housing. It is recently proposed soft materials that reduce the impact noise. However, it is a fact that the application of soft sound insulation includes some problem about structural performance. In this study, we made wet-heating specimen with various sound insulations, and carried out structralexperiment for evaluating the structural safety of it.

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Analysis on the Structural Safety of the Tower Crane under Load (하중을 받는 타워크레인의 구조 안전성 해석)

  • Cho, Jae-Ung;Kim, Sei-Hwan
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.11 no.10
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    • pp.3641-3646
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    • 2010
  • In this study, the deformation analysis is done at tower crane by applying the load at the end of jib and the moment at mast. The greatest stain and stress are happened at the end of wire supporting jib. The great deformation takes place at the end of jib applied by stress and there is no deformation at the lower part of mast. As the life becomes smallest at the upper part of mast, this part becomes weakest. The safety design and durability can be improved by applying the result of structural safety analysis at tower crane.

Probabilistic Finite Element Analysis of Plane Frame (평면 FRAME 구조물의 확률유한요소 해석)

  • 양영순;김지호
    • Computational Structural Engineering
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    • v.2 no.4
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    • pp.89-98
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    • 1989
  • In order to take account of the statistical properties of random variables used in the structural analysis, the conventional approach usually adopts the safety factor based on past experiences for the qualitative assessment of structural safety problem. Recently, new approach based on the probabilistic concept has been applied to the assessment of structural safety in order to circumvent the difficulties of the conventional approach in choosing the appropriate safety factor. Thus, computer program called "Probabilistic finite element method" is developed by incorporating the probabilistic concept into the conventional matrix method in order to investigate the effects of the random variables on the final output of the structural analysis. From the comparison of some examples, it can be concluded that the PFEM developed in this study deals consistently with the uncertainty of random variables and provides the rational tool for the assessment of structural safety of plane frame.

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A Study on Structural Safety of Integrated Machine for Grinding Wheel Forming (연삭 휠 형상 복합가공시스템의 구조 안전성에 관한 연구)

  • Lee, Won-Suk;An, Beom-Sang;Kim, Jin-Hyeon;Lee, Jong-Chan;Woo, Bong-Geun;Lee, Young-Sik
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.15 no.2
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    • pp.84-88
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    • 2016
  • This study evaluated the structural safety of a heavy-duty integrated machine for grinding wheel forming. Structural analysis was performed to evaluate the structural safety of the base. The base was designed by dividing the single base and detachable base. The analysis conditions were applied to the own weight and the load of component parts. From the structural analysis results, although the stress of the detachable base was decreased, the amount of deformation was increased. If the deformation of the detachable base decreases, it is expected to be safer than the single base.

Study on Structural Safety of Automotive Inner and Outer Bumper (차체 안쪽과 바깥쪽 범퍼의 구조 안전성에 관한 연구)

  • Han, Moon-Sik;Cho, Jae-Ung
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.10 no.2
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    • pp.130-134
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    • 2011
  • This study aims at the structural safety with optimum design of automotive bumper in order to minimize the maximum stress and displacement and reduce the minimum quantity of bumper material. As the forces of X and Y direction increase, equivalent stress and displacement increase. The displacement of X direction force increases more than 20% in comparison with Y direction force. But the equivalent stress of Y direction force increases more than 60% in comparison with X direction force. The mass of inner bumper becomes minimum and the mass of outer bumper becomes maximum when the force of 4000N is applied on the direction inclined at $45^{\circ}$ toward outer bumper. In 50% range of increase and decrease at X and Y direction force, the optimum forces of X and Y component becomes 2368.8N and 1538.8N respectively. And the masses of inner and outer polypropylene bumper become $3.3227{\times}10^{-2}kg$and $3.5538{\times}10^{-2}kg$respectively.

Fatigue Strength Analysis of Marine Propeller Blade to Change in Skew Angle (박용 프로펠라의 스큐각 변화에 따른 피로강도해석)

  • Bal-Young Kim;Joo-Sung Lee
    • Journal of the Society of Naval Architects of Korea
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    • v.35 no.1
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    • pp.80-87
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    • 1998
  • This paper deals with the evaluation of structural safety to fatigue strength of marine propeller blades having high skew angle and operating in irregular wake field. The determination of the optimum skew angle of a propeller blade is one of the important task at the initial design stage especially in the case of high speed vessel such as container ships. A computer program system has been developed to evaluate the structural safety to fatigue strength and has been applied to several propeller blades with varying skew angle within a wide range. In the parametric study the pressure acting on the blade surface is calculated using the non-lineal lifting surface theory and the structural analysis is performed using MSC/NASTRAN. The relationship between skew angle and structural safety to fatigue strength is investigated and this paper ends with describing the optimum skew angle of a propeller blade.

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