Papers by Keyword: Failure Probability

Abstract: Stiffened plate is widely used in vessel structure because of its high bearing capacity and low weight so the research of failure probability for stiffened plate under explosion load has important engineering meaning. Stiffened plate under near-field explosion is taken as research subject, dynamite density and yield stress of plate are selected as random variables, the original values of one hundred groups of random variables are gotten through the random number generation program, and the moments of random variables are obtained. Based on failure criterion of displacement ductility, the performance function of structure is established, probability density function of performance function is fitted using maximum entropy method then the failure probability of stiffened plate structure is obtained. So as to solve the problem of calculate failure probability when the sample size is small and the probability density function is unknown.

Abstract: As a bridge assessment method, risk assessment is more and more applied to load-carrying capacity assessment of existing bridge. This method assesses the bridge through the failure risk value which calculated by the failure probability and failure loss value. The most important factor to the risk assessment of load-carrying capacity upon the existing and diseased bridge is the calculation of failure probability. This paper combines the reliability calculation theory with a certain site detective data of bridge that considering uncertainty of load and resistance along with the diseases of bridge, and induces in the correction coefficient of load and resistance respectively to calculate the failure probability and reliability index of bridge. Finally, these indexes are compared with those provided by the current code to implement risk assessment of load-carrying capacity of the bridge.

Abstract: This paper presents the Bayesian analysis of the zero-failure data with double hyper parameters a, b. We take prior distribution of failure probability pi be its conjugated distribution—Beta (pi-1, 1, 1, b) and hyper parameter b as the uniform distribution in (1, c). With quadratic loss function, If pi  (pi-1, 1), the E-Bayesian estimation of pi is . When 0 < c < si, and satisfy (I) ;(II) . The results satisfy . The properties of E-Bayesian estimation are given. A Simulation example is discussed, which shows that the method is both efficiency and easy to operate.

Abstract: For slope risk analysis of tailings dam, the current research focuses on treating physical and mechanical parameters of tailing materials as the basic random variables. The influence of the external natural random factors is considered little. In practice, the slope stability of tailings dam is influenced by not only their random material parameters but the various natural factors including the changes of water level and the seismic intensity size. As a rule of thumb, there might be heavy rains before the earthquake. Therefore, it is necessary to comprehensively consider the slope risk of tailings dam under the coupling effect of rainstorms and earthquakes. Aiming at this problem, reliability theory was employed in this paper to study the influence under both rainstorms and earthquake actions. In this project, the slope risk analysis of tailings dams is evaluated under natural multi-random factors.

Abstract: In this paper, the probability theory was applied in the stability analysis of a potential landslide, which is located at Lishan Mountain, China. By employing a cyclic loading ring shear apparatus, the geotechnical parameters in the stability analysis was measured under the testing conditions of simulating earthquake and heavy rainfall. Based on the calculation results, the failure probability as well as the stability of Lishan potential landslide was discussed. The results show that Lishan landslide is unstable under cyclic loading and become very dangerous to failure at the time of heavy rainfall.

Abstract: Drag suction hopper dredger is dredg the hard compacted soil,dreghead teeth intensity will lead to an undersized cutting depth and a large cutting resistance, it raise failure probability. In this paper, investigate the relation between dredging depth，width,resistance and draghead teeth reliability influenced under different conditions,including various teeth,loads,navigating speeds and high-pressure jets.Discussed their effects on cutting depth,width and resistance.At last this paper obtain the reliability index and failure probability of the draghead teeth through the calculation numerical example.In this example,the method improvements efficiency for Draghead Teeth based on analysis on reliability.

Abstract: The complexity of the geological conditions and the non-uniformity of geotechnical material make the study of slope stability with big uncertainties, so it is necessary to analyze the reliability of slope. In this paper, firstly, the matrix suction of Malan loess in Gansu Province is measured by tension meter, and a fitted soil-water characteristic curve (SWCC) is obtained according to the empirical formula; then SWCC parameters of Malan loess such as a, n and θs (saturation volumetric water content) are thought as random variables, the method of simplified Bishop is used to calculate of slope stability, and the reliability of cutting slope of Malan loess is analyzed according to Rosenbleuth method. Through calculating, obtain mean factor of safety, failure probability and reliability index of the slope. After analyzing the relations between mean factor of safety, failure probability, reliability index and variability of parameters, the results show that, the factor of safety is 1.005 and it is stable when the variability of SWCC parameters are not considered. When variation coefficients of a, n and θs are all 0.3, the average factor of safety is 1.051, the reliability index is 10.94 and failure probability is 29.81%. It is obvious that variability of SWCC parameters has certain influence on stability of the slope. In parameters of SWCC, comparing with a and θs, the variability of n has the most important influence on the mean factor of safety and failure probability. But the corresponding reliability index is minimum (the change ratios of the mean factor of safety， failure probability and reliability index with variation coefficient of n are 0.37，3.247 and 282.0 respectively). So variation level of n should be specially taken into account in reliability analysis of the slope. This research provides an important basis for the determination of the SWCC parameters of Malan loess, the stability calculation, stability estimation and prevention sliding of loess cutting slope caused by rainfall.

Abstract: This paper analyzed the board of reliability on the elastic half space model. Considered the random of the larger variability parameters, such as foundation, board, load, the paper studied the reliability of this issue application of the response surface method of quadratic polynomials. This paper analyzed the influence of the random parameter variability on the reliability index β and failure probability, obtained some useful conclusions and had some engineering referencing.

Abstract: Failure probability of a component is the major project of engineering probability. The reliability of a mechanical system or a structural system is calculated by components in the system. However, statistics data shows that the distribution of test data of components is not according with the distribution by theory as normal distribution. Normal distribution is extensively applied in the component reliability nowadays. Its domain is the field of real numbers, whereas, test data of exper-iments are on a finite field. Consequently, the component reliability used the normal distributions has some limitations. It is necessary to choose a suitable distribution in the calculating method. Comparing the normal distribution density curve and the statistics graph, a new distribution is pre-sented in this paper. The examples by both normal distribution and the new distribution are given, respectively. The results suggest that the new distribution is more accurate than normal distribution in the component reliability.

Abstract: Considering the various factors which influenced the safety of hoist system, and the general objective which was the failure probability of hoist system, it established the safety risk assessment model for hoist system. Then it used the time-varying effect to forecast the failure probability and crash damage of hoist system. It constructed the evaluation index system, and used the AHP method, the fuzzy mathematics method and the method of expert advice on weight distribution at various levels. Based on the evaluation and analysis of Zhuzhuang reservoir projects on the gate crane, it proved that the safety risk assessment model for hoist system was scientific, safety and reliability.