• Title/Summary/Keyword: Failure zone

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Characteristics of Fatigue Failure according to Thickness of Material and Number of Passes in Cruciform Fillet Weld Zone (십자형 필릿 용접부에서 재료 두께 및 용접 층수에 따른 피로파괴 특성)

  • Lee, Yong-Bok
    • Journal of Welding and Joining
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    • v.28 no.6
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    • pp.45-50
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    • 2010
  • Most of joining processes for machine and steel structure are performed by butt and fillet welding. The mechanical properties and fatigue strength of their welding zone can be effected largely by the differential of generated heat and changes of grain size according to thickness of material and number of passes in welding process. In this study, it was investigated about characteristics of fatigue failure according to thickness of material and number of passes in cruciform fillet weld zone as the basic study for safe and economic design of welding structures. Fracture modes in cruciform fillet weld zone are classified into toe failure and root failure according to non-penetrated depth. It can be accomplished economic design of welding structures considering fatigue strength when the penetrated depth in fillet weld zone is controled properly.

Failure Zone Estimation from the correlation between the Temperature in Slope and the Soil Nail Strain (지중온도와 변형율과의 상관관계를 통한 활동영역의 추정)

  • Chang, Ki-Tae
    • Journal of the Korean Geophysical Society
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    • v.8 no.3
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    • pp.123-130
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    • 2005
  • It is necessary, in the light of the importance of long-term slope stability problem, to develop a simple method or tool which can figure out the possible failure zone resulted from weathering effect and other factors. The FBG sensor system is used to estimate the correlations between the temperature and the slope in Kimhae, and to find a failure zone in slopes effectively. This research is to seek for the correlation between the soil temperature distribution and the strain distribution in a active zone by analyzing the data from the in-situ measurement so that the possible failure zone should be well defined based on the correlation. For instance, the zone of high temperature fluctuation can be regarded as one of the possible sliding zone due to the weathering effect while the constant temperature depth of the ground, if exists would not be relatively affected by the weathering process.

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Deformation Estimation of Slope Reinforced Materials by Rain and Temperature (사면보강재의 강우 및 온도에 의한 변형 해석)

  • 홍성진;장기태;한희수
    • Proceedings of the Korean Geotechical Society Conference
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    • 2002.10a
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    • pp.643-650
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    • 2002
  • It is necessary, in the light of the importance of long-term slope stability problem, to develop a simple method or tool which can figure out the possible failure zone resulted from weathering effect and other factors. The FBG sensor system is used to estimate the correlations between the temperature and the slope in Yunhwajae, and to find a failure zone in slopes effectively. This research is to seek for the correlation between the soil temperature distribution and the strain distribution in a active zone by analyzing the data from the in-situ measurement so that the possible failure zone should be well defined based on the correlation. The zone of high temperature fluctuation can be regarded as one of the possible sliding zone due to the weathering effect while the constant temperature depth of the ground, if exists, would not be relatively affected by the weathering process.

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Behavior of Failure for Embankment and Spillway Transitional Zone of Agriculture Reservoirs due to Overtopping (농업용 저수지 월류시 제체와 여수토 접속부의 붕괴거동)

  • Noh, Jae Jin;Lee, Dal Won
    • Journal of The Korean Society of Agricultural Engineers
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    • v.56 no.1
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    • pp.71-79
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    • 2014
  • In this study, an experiment with large-scale model was performed according to raising the embankment in order to investigate the behavior of failure for embankment and spillway transitional zone due to overtopping. The pore water pressure, earth pressure, settlement and failure pattern by a rapid drawdown and overtopping were compared and analyzed. The pore water pressure and earth pressure at spillway transitional zone by overtopping increased a rapidly with the expansion of seepage erosion, but the crest showed a smally change due to effect of the inclined core type. And it is considered an useful data that can accurately estimate the possibility of failure of the reservoirs. A settlement at overtopping decreased a rapidly due to failure of crest. The relative settlement difference due to change of the water level at the upstream and downstream slope cause increase largely crack of crest. The behavior of failure by overtopping was gradually enlarged towards reservoirs crest from the bottom of the spillway transition zone, the inclined core after the raising the embankment was influenced significantly to prevent the seepage erosion.

Monte Carlo analysis of the induced cracked zone by single-hole rock explosion

  • Shadabfar, Mahdi;Huang, Hongwei;Wang, Yuan;Wu, Chenglong
    • Geomechanics and Engineering
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    • v.21 no.3
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    • pp.289-300
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    • 2020
  • Estimating the damage induced by an explosion around a blast hole has always been a challenging issue in geotechnical engineering. It is difficult to determine an exact dimension for damage zone since many parameters are involved in the formation of failures, and there are some uncertainties lying in these parameters. Thus, the present study adopted a probabilistic approach towards this problem. First, a reliability model of the problem was established and the failure probability of induced damage was calculated. Then, the corresponding exceedance risk curve was developed indicating the relation between the failure probability and the cracked zone radius. The obtained risk curve indicated that the failure probability drops dramatically by increasing the cracked zone radius so that the probability of exceedance for any crack length greater than 4.5 m is less than 5%. Moreover, the effect of each parameter involved in the probability of failure, including blast hole radius, explosive density, detonation velocity, and tensile strength of the rock, was evaluated by using a sensitivity analysis. Finally, the impact of the decoupling ratio on the reduction of failures was investigated and the location of its maximum influence was demonstrated around the blast point.

Analysis and Application of Mechanical Clinched Joint Using Cohesive Zone Model (접착영역모델을 이용한 클린칭 접합부의 해석 모델 설계 및 적용)

  • Hwang, B.N.;Lee, C.J.;Lee, S.B.;Kim, B.M.
    • Transactions of Materials Processing
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    • v.19 no.4
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    • pp.217-223
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    • 2010
  • The objective of this study is to propose the FE model for mechanical clinched joint using cohesive zone model to analyze its failure behavior under impact loading. Cohesive zone model (CZM) is two-parameter failure criteria approach, which could describe the failure behavior of joint using critical stress and fracture toughness. In this study, the relationship between failure behavior of mechanical clinched joint and fracture parameters is investigated by FE analysis with CZM. Using this relationship, the critical stress and fracture toughness for tensile and shear mode are determined by H-type tensile test and lap shear test, which were made of 5052 aluminum alloy. The fracture parameters were applied to the tophat impact test to evaluate the crashworthiness. Compared penetration depth and energy absorption at the point where 50% of total displacement in result of FE analysis and experiment test for impact test, those has shown similar crashworthiness.

Study on Strain Localization and Progressive Failure of Concrete (콘크리트의 변형률 국소화 및 진행성 파괴에 관한 연구)

  • 송하원;김형운;우승민
    • Journal of the Korea Concrete Institute
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    • v.11 no.3
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    • pp.181-192
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    • 1999
  • The progressive failure following strain localization in concrete can be analyzed effectively using finite element modeling of fracture process zone of concrete with a finite element embedded discontinuity. In this study, a finite element with embedded discontinuous line is utilized for the analysis of progressive failure in concrete. The finite element with embedded discontinuity is a kind of discrete crack element, but the difficulties in discrete crack approach such as remeshing or adding new nodes along with crack growth can be avoided. Using a discontinuous shape function for this element, the displacement discontinuity is embedded within an element and its constitutive equation is modeled from the modeling of fracture process zone. The element stiffness matrix is derived and its dual mapping technique for numerical integration is employed. Then, a finite element analysis program with employed algorithms is developed and failure analysis results using developed finite element program are verified through the comparison with experimental data and other analysis results.

Experiment and bearing capacity analyses of dual-lintel column joints in Chinese traditional style buildings

  • Xue, Jianyang;Ma, Linlin;Wu, Zhanjing;Zhai, Lei;Zhang, Xin
    • Steel and Composite Structures
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    • v.28 no.5
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    • pp.641-653
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    • 2018
  • This paper presents experiment and bearing capacity analyses of steel dual-lintel column (SDC) joints in Chinese traditional style buildings. Two SDC interior joints and two SDC exterior joints, which consisted of dual box-section lintels, circular column and square column, were designed and tested under low cyclic loading. The force transferring mechanisms at the panel zone of SDC joints were proposed. And also, the load-strain curves at the panel zone, failure modes, hysteretic loops and skeleton curves of the joints were analyzed. It is shown that the typical failure modes of the joints are shear buckling at bottom panel zone, bending failure at middle panel zone, welds fracturing at the panel zone, and tension failure of base metal in the heat-affected zone of the joints. The ultimate bearing capacity of SDC joints appears to decrease with the increment of axial compression ratio. However, the bearing capacities of exterior joints are lower than those of interior joints at the same axial compression ratio. In order to predict the formulas of the bending capacity at the middle panel zone and the shear capacity at the bottom panel zone, the calculation model and the stress state of the element at the panel zone of SDC joints were studied. As the calculated values showed good agreements with the test results, the proposed formulas can be reliably applied to the analysis and design of SDC joints in Chinese traditional style buildings.

Deformation Estimation of Slope Reinforced Materials by Rain and Temperature (사면보강재의 강우 및 온도에 의한 변형 해석)

  • Hong, Sung-Jin;Chang, Ki-Tae;Han, Heui-Soo
    • Journal of the Korean Geophysical Society
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    • v.8 no.2
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    • pp.97-103
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    • 2005
  • It is necessary, in the light of the importance of long-term slope stability problem, to develop a simple method or tool which can figure out the possible failure zone resulted from weathering effect and other factors. The FBG sensor system is used to estimate the correlations between the temperature and the slope in Yunhwajae, and to find a failure zone in slopes effectively. This research is to seek for the correlation between the soil temperature distribution and the strain distribution in a active zone by analyzing the data from the in-situ measurement so that the possible failure zone should be well defined based on the correlation. The zone of high temperature fluctuation can be regarded as one of the possible sliding zone due to the weathering effect while the constant temperature depth of the ground, if exists, would not be relatively affected by the weathering process.

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A Mechanical Model of the End Anchorage Zone of Prestressed Concrete Members

  • Kang, Won-Ho;You, Young-Min;Oh, Seung-Hyun;Lee, Sang-Woo
    • International Journal of Concrete Structures and Materials
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    • v.18 no.1E
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    • pp.35-41
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    • 2006
  • It is expected that recent development of mechanical models will soon supersede previous empirical methods of detailing. In this study, a mechanical model is proposed to analyze the behavior of the anchorage zone of prestressed concrete members. The main characteristics of the proposed model lies in its rational consideration of material properties such as concrete strength in biaxial stress state and that of local zone reinforced by spirals. The shear friction strength of concrete surrounding a spiral is also considered. The computational results of the proposed model as well as the existing Strut-and-Tie model(STM) and nonlinear finite element analysis are compared with experimental results. The results of the comparison revealed that the proposed model showed better prediction of the failure mode as well as the failure load. Additionally, the proposed model also explained the three-dimensional failure mechanism very well, while other methods based on two-dimensional analysis could not do so well.