The Experts below are selected from a list of 219 Experts worldwide ranked by ideXlab platform

Liu Zhu-ping - One of the best experts on this subject based on the ideXlab platform.

R. K. Bhasin - One of the best experts on this subject based on the ideXlab platform.

  • Probabilistic Stability Evaluation of Oppstadhornet Rock Slope, Norway
    Rock Mechanics and Rock Engineering, 2008
    Co-Authors: H. S. B. Duzgun, R. K. Bhasin
    Abstract:

    Probabilistic analyses provide rational means to treat the uncertainties associated with underlying parameters in a systematic manner. The stability of a 734-m-high jointed rock slope in the west of Norway, the Oppstadhornet rock slope, is investigated by using a probabilistic method. The first-order reliability method (FORM) is used for probabilistic modeling of the plane failure problem in the rock slope. The Barton–Bandis (BB) shear strength criterion is used for the Limit State Equation. The statistical distributions of the BB criterion parameters, for which comprehensive data were collected and statistically analyzed, are determined by using distribution fitting algorithms. The sensitivity of the FORM model for the BB criterion is also investigated. It is found that the model is most sensitive to the mean value of the residual friction angle ( ϕ _r) and least sensitive to the mean value of the slope angle ( β _f). It is also found that the standard deviation of joint compressive strength (JCS) causes the greatest difference in the reliability index, which has the least sensitivity to the change in the mean and standard deviation of joint roughness coefficient (JRC).

Lu Zhenzhou - One of the best experts on this subject based on the ideXlab platform.

  • Support Vector Machine response surface method based on fast Markov chain simulation
    2009 IEEE International Conference on Intelligent Computing and Intelligent Systems, 2009
    Co-Authors: Yuan Xiukai, Lu Zhenzhou, Lu Yuanbo
    Abstract:

    The support vector machine (SVM) response surface method (RSM) is proposed on fast Markov chain simulation for the problem with implicit Limit State function usually encountered in engineering reliability analysis and design. In the proposed method, Markov chain is used to generate the samples in the important region of the Limit State function, and the SVM is employed to construct the response surface by use of these samples. Since Markov chain can adaptively simulate the samples in the important region, and the candidate State but not Markov State is used as the training samples for SVM, the proposed method can well approximate the Limit State Equation in the zone surrounding the design point, and can make full use of information provided by Markov chain simulation. In addition, the iterative strategy is adopted to improve the convergence speed of the failure probability. Moreover, the proposed method uses the SVM regression method to construct the response surface, which can automatically apply the structural risk minimization (SRM) inductive principle in approximating the Limit State Equation, thus it can approximate the failure probability with high accuracy. Finally applications in a numerical example and an engineering example indicate that the proposed method owns good performance in calculating efficiency and accuracy.

  • a composite response surface method for failure probability calculation of nonlinear implicit Limit State Equation
    Engineering mechanics, 2006
    Co-Authors: Lu Zhenzhou
    Abstract:

    To solve failure probability of the implicit Limit State Equation with high curvature in the vicinity of the design point,a new composite response surface method(RSM) is presented.The major response surface and some sub-response surfaces are adopted in the method.The function form of response surface is taken as a quadratic polynomial without cross terms.According to the conventional RSM,the major response surface is obtained by the proper selection of sampling points and iterative calculation.The design point of the major response surface is named as the major design point.A pair of quasi-mean value points are taken by perturbing the major design point along the positive and negative direction of each coordinate axis.Based on the quasi-mean value point,a pair of sub-response surfaces are obtained in the similar manner as the major response surface.And the tangent hypersurfaces of all response surfaces are used to fit the actual implicit Limit State Equation and solve failure probability.Illustrations show that the accuracy of the present method is very high.

Zach Liang - One of the best experts on this subject based on the ideXlab platform.

  • Bridge pier failure probabilities under combined hazard effects of scour, truck and earthquake. Part I: occurrence probabilities
    Earthquake Engineering and Engineering Vibration, 2013
    Co-Authors: Zach Liang
    Abstract:

    In many regions of the world, a bridge will experience multiple extreme hazards during its expected service life. The current American Association of State Highway and Transportation Officials (AASHTO) load and resistance factor design (LRFD) specifications are formulated based on failure probabilities, which are fully calibrated for dead load and nonextreme live loads. Design against earthquake loads is established separately. Design against scour effect is also formulated separately by using the concept of capacity reduction (or increased scour depth). Furthermore, scour effect cannot be linked directly to an LRFD Limit State Equation, because the latter is formulated using force-based analysis. This paper (in two parts) presents a probability-based procedure to estimate the combined hazard effects on bridges due to truck, earthquake and scour, by treating the effect of scour as an equivalent load effect so that it can be included in reliability-based bridge failure calculations. In Part I of this series, the general principle of treating the scour depth as an equivalent load effect is presented. The individual and combined partial failure probabilities due to truck, earthquake and scour effects are described. To explain the method of including non-force-based natural hazards effects, two types of common scour failures are considered. In Part II, the corresponding bridge failure probability, the occurrence of scour as well as simultaneously having both truck load and equivalent scour load are quantitatively discussed.

  • Bridge pier failure probabilities under combined hazard effects of scour, truck and earthquake. Part II: failure probabilities
    Earthquake Engineering and Engineering Vibration, 2013
    Co-Authors: Zach Liang
    Abstract:

    In many regions of the world, a bridge will experience multiple extreme hazards during its expected service life. The current American Association of State Highway and Transportation Officials (AASHTO) load and resistance factor design (LRFD) specifications are formulated based on failure probabilities, which are fully calibrated for dead load and non-extreme live loads. Design against earthquake load effect is established separately. Design against scour effect is also formulated separately by using the concept of capacity reduction (or increased scour depth). Furthermore, scour effect cannot be linked directly to an LRFD Limit State Equation because the latter is formulated using force-based analysis. This paper (in two parts) presents a probability-based procedure to estimate the combined hazard effects on bridges due to truck, earthquake and scour, by treating the effect of scour as an equivalent load effect so that it can be included in reliability-based failure calculations. In Part I of this series, the general principle for treating the scour depth as an equivalent load effect is presented. In Part II, the corresponding bridge failure probability, the occurrence of scour as well as simultaneously having both truck load and equivalent scour load effect are quantitatively discussed. The key formulae of the conditional partial failure probabilities and the necessary conditions are established. In order to illustrate the methodology, an example of dead, truck, earthquake and scour effects on a simple bridge pile foundation is represented.

H. S. B. Duzgun - One of the best experts on this subject based on the ideXlab platform.

  • Probabilistic Stability Evaluation of Oppstadhornet Rock Slope, Norway
    Rock Mechanics and Rock Engineering, 2008
    Co-Authors: H. S. B. Duzgun, R. K. Bhasin
    Abstract:

    Probabilistic analyses provide rational means to treat the uncertainties associated with underlying parameters in a systematic manner. The stability of a 734-m-high jointed rock slope in the west of Norway, the Oppstadhornet rock slope, is investigated by using a probabilistic method. The first-order reliability method (FORM) is used for probabilistic modeling of the plane failure problem in the rock slope. The Barton–Bandis (BB) shear strength criterion is used for the Limit State Equation. The statistical distributions of the BB criterion parameters, for which comprehensive data were collected and statistically analyzed, are determined by using distribution fitting algorithms. The sensitivity of the FORM model for the BB criterion is also investigated. It is found that the model is most sensitive to the mean value of the residual friction angle ( ϕ _r) and least sensitive to the mean value of the slope angle ( β _f). It is also found that the standard deviation of joint compressive strength (JCS) causes the greatest difference in the reliability index, which has the least sensitivity to the change in the mean and standard deviation of joint roughness coefficient (JRC).