• Journal of the Korea Society of Computer and Information
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• v.10 no.6 s.38
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• pp.27-36
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• 2005

Finite failure NHPP models presented in the literature exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates Per fault. This Paper Proposes reliability model using the generalized gamma distribution, which can capture the monotonic increasing(or monotonic decreasing) nature of the failure occurrence rate per fault. Equations to estimate the parameters of the generalized gamma finite failure NHPP model based on failure data collected in the form of interfailure times are developed. For the sake of proposing shape parameter of the generalized gamma distribution, used to the special pattern. Data set, where the underlying failure process could not be adequately described by the knowing models, which motivated the development of the gamma or Weibull model. Analysis of failure data set for the generalized gamma modell, using arithmetic and Laplace trend tests . goodness-of-fit test, bias tests is presented.

• Steel and Composite Structures
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• v.52 no.4
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• pp.391-403
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• 2024

The flexural behavior of composite sandwich wall panels with different thicknesses, numbers of holes, and hole forms, and arrangement form of longitudinal steel bar (uniform type and concealed-beam type) are investigated. A total of twelve composite sandwich wall panels are prepared, utilizing modified polystyrene particles mixed with foam concrete for the flexural performance test. The failure pattern of the composite sandwich wall panels is influenced by the extruded polystyrene panel (XPS) panel thickness and the reinforcement ratio in combination, resulting in both flexural and shear failure modes. Increasing the XPS panel thickness causes the specimens to transition from flexural failure to shear failure. An increase in the reinforcement ratio leads to the transition from flexural failure to shear failure. The hole form on the XPS panel and the steel bar arrangement form affect the loading behavior of the specimens. Plum-arrangement hole form specimens exhibit lower steel bar strain and deflection compared to linear-arrangement hole form specimens. Additionally, specimens with concealed beam-type steel bar display lower steel bar strain and deflection than uniform-type steel bar specimens. However, the hole form and steel bar arrangement form have a limited impact on the ultimate load. Theoretical formulas for cracking load are provided for both fully composite and non-composite states. When compared to the experimental values, it is observed that the cracking load of the specimens with XPS panels closely matches the calculations for the non-composite state. An accurate prediction model for the ultimate load of fully composite wall panels is developed. These findings offer valuable insights into the behavior of composite sandwich wall panels and provide a basis for predicting their performance under various design factors and conditions.

• Structural Engineering and Mechanics
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• v.36 no.3
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• pp.247-278
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• 2010

The study of the seismic vulnerability of masonry buildings requires structural properties of walls such as stiffness, ultimate load capacity, etc. In this article, a method is suggested for modeling the masonry walls under in-plane loading. At the outset, a set of analytical equations was established for determining the elastic properties of an equivalent homogeneous material of masonry. The results for homogenized unreinforced brick walls through detailed modeling were compared in different manners such as solid and perforated walls, in-plane and out-of-plane loading, etc, and it was found that this method provides suitable accuracy in estimation of the wall linear properties. Furthermore, comparison of the results of proposed modeling with experimental out coming indicated that this model considers the non linear properties of the wall such as failure pattern, performance curve and ultimate strength, and would be appropriate to establish a parametric study on those prone factors. The proposed model is complicated; therefore, efforts need to be made in order to overcome the convergency problems which will be included in this study. The nonlinear model is basically semi-macro but through a series of actions, it can be simplified to a macro model.

• Computers and Concrete
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• v.21 no.4
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• pp.451-461
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• 2018

Present study is mainly concerned about the idea of innovative utilization of bamboo in modern construction. Owing to its compatible mechanical properties, a beneficial effect of its use in reinforced concrete (RC) frame infills has been observed. In this investigation, finite element analyses have been performed to examine the failure pattern and stress distribution pattern through the infills of a moment resisting RC frame. To validate the pragmatic use of bamboo reinforced components as infills, earthquake loading corresponding to Nepal earthquake had been considered. The analysis have revealed that introduction of bamboo in RC frames imparts more flexibility to the structure and hence may causes a ductile failure during high magnitude earthquakes like in Nepal. A more uniform stress distribution throughout the bamboo reinforced wall panels validates the practical feasibility of using bamboo reinforced concrete wall panels as a replacement of conventional brick masonry wall panels. A more detailed analysis of the results have shown the fact that stress concentration was more on the frame components in case of frame with brick masonry, contrary to the frame with bamboo reinforced concrete wall panels, in which, major stress dispersion was through wall panels leaving frame components subjected to smaller stresses. Thus an effective contribution of bamboo in dissipation of stresses generated during devastating seismic activity have been shown by these results which can be used to concrete the feasibility of using bamboo in modern construction.

• Geomechanics and Engineering
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• v.13 no.6
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• pp.1045-1055
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• 2017

Tensile strength is considered key properties for characterizing rock material in engineering project. It is determined by direct and indirect methods. Point load test is a useful testing method to estimate the tensile strengths of rocks. In this paper, the effects of rock shape on the point load index of gypsum are investigated by PFC2D simulation. For PFC simulating, initially calibration of PFC was performed with respect to the Brazilian experimental data to ensure the conformity of the simulated numerical models response. In second step, nineteen models with different shape were prepared and tested under point load test. According to the obtained results, as the size of the models increases, the point load strength index increases. It is also found that the shape of particles has no major effect on its tensile strength. Our findings show that the dominant failure pattern for numerical models is breaking the model into two pieces. Also a criterion was rendered numerically for determination of tensile strength of gypsum. The proposed criteria were cross checked with the results of experimental point load test.

• Structural Engineering and Mechanics
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• v.69 no.1
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• pp.51-67
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• 2019

In this paper, the anisotropy of tensile behaviours of layered rocks consisting internal notch has been investigated using particle flow code. For this purpose, firstly calibration of PFC2D was performed using Brazilian tensile strength. Secondly Brazilian test models consisting bedding layer was simulated numerically. Thickness of layers was 10 mm and layered angularity was $90^{\circ}$, $75^{\circ}$, $60^{\circ}$, $45^{\circ}$, $30^{\circ}$, $15^{\circ}$ and $0^{\circ}$. The strength of bedding interface was too high. Each model was consisted of one internal notch. Notch length is 1 cm, 2 cm and 4 cm and notch angularities are $60^{\circ}$, $45^{\circ}$, $30^{\circ}$, $15^{\circ}$ and $0^{\circ}$. Totally, 90 model were tested. The results show that failure pattern was affected by notch orientation and notch length. It's to be noted that layer angle has not any effect on the failure pattern. Also, Brazilian tensile strength is affected by notch orientation and notch length.

• Journal of the Earthquake Engineering Society of Korea
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• v.25 no.5
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• pp.191-199
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• 2021

In seismic design, hollow section concrete columns offer advantages by reducing the weight and seismic mass compared to concrete section RC bridge columns. However, the flexure-shear behavior and spirals strain of hollow section concrete columns are not well-understood. Octagonal RC bridge columns of a small-scale model were tested under cyclic lateral load with constant axial load. The volumetric ratio of the transverse spiral hoop of all specimens is 0.00206. The test results showed that the structural performance of the hollow specimen, such as the initial crack pattern, initial stiffness, and diagonal crack pattern, was comparable to that of the solid specimen. However, the lateral strength and ultimate displacement of the hollow specimen noticeably decreased after the drift ratio of 3%. The columns showed flexure-shear failure at the final stage. Analytical and experimental investigations are presented in this study to understand a correlation confinement steel ratio with neutral axis and a correlation between the strain of spirals and the shear resistance capacity of steel in hollow and solid section concrete columns. Furthermore, shear strength components (V_c, V_s·, V_p) and concrete stress were investigated.

• Journal of Technologic Dentistry
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• v.43 no.4
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• pp.160-167
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• 2021

Purpose: In this study, when the etching treatment method, which is a chemical surface treatment method, is applied to colored zirconia, the shear bond strength between the veneering ceramic material and colored zirconia is compared with that without surface treatment, and the fracture type is observed to evaluate the etching treatment effect of colored zirconia. Methods: Experiments were conducted after dividing the study sample into two groups, which are the zirconia control group without surface treatment using colored zirconia blocks (without etching zirconia, NZC group) and the zirconia group treated with a commercially available etching solution (etching liquid zirconia, EZC group). Results: The mean shear bond strength of the NZC group was 20.31±2.32 Mpa, and that of the EZC group was 25.95±2.34 Mpa, and the difference between these two values was statistically significant (p<0.05). Further, the surface roughness Ra value was higher in the EZC group than in the NZC group. In the fracture pattern, cohesive fractures were dominant, and adhesive fractures and cohesive fractures were mixed. Conclusion: The bond strength was significantly higher in the group treated with colored zirconia. The fracture pattern was mostly cohesive failure in the group not treated with etching and changed to mixed failure as the etching treatment progressed.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.5
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• pp.469-475
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• 2017

Software reliability is one of the most basic and essential problems in software development. In order to detect the software failure phenomenon, the intensity function, which is the instantaneous failure rate in the non-homogeneous Poisson process, can have the property that it is constant, non-increasing or non-decreasing independently at the failure time. In this study, was compared the reliability performance of the software reliability model using the Landely lifetime distribution with the intensity function decreasing pattern and Erlang lifetime distribution from increasing to decreasing pattern in the software product testing process. In order to identify the software failure phenomenon, the parametric estimation was applied to the maximum likelihood estimation method. Therefore, in this paper, was compared and evaluated software reliability using software failure interval time data. As a result, the reliability of the Landely model is higher than that of the Erlang distribution model. But, in the Erlang distribution model, the higher the shape parameter, the higher the reliability. Through this study, the software design department will be able to help the software design by applying various life distribution and shape parameters, and providing software reliability attributes data and basic knowledge to software reliability model using software failure analysis.

• Journal of IKEEE
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• v.9 no.2 s.17
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• pp.143-151
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• 2005

Finite failure NHPP models proposed in the literature exhibit is either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault. For the sake of proposing shape parameter of the Gamma family distribution, used the special pattern. Data set, where the underlying failure process could not be adequately described by the knowing models, which motivated the development of the Gamma or Weibull model and Gompertz model. Analysis of failure data set that led us to the Gamma or Weibull model and Gompertz model using arithmetic and Laplace trend tests, bias tests was presented in this Paper.