Reliability Analysis of a Mechanism with Grey System Parameters

2012 ◽  
Vol 538-541 ◽  
pp. 3154-3159 ◽  
Author(s):  
Jian Guo Zhang ◽  
Jian Jun Chen ◽  
Jing Li Du
Keyword(s):  
Reliability Analysis ◽  
Limit State ◽  
Assessment Method ◽  
Theory Model ◽  
Grey Theory ◽  
Grey System ◽  
State Equations ◽  
System Parameters ◽  
Gray Theory ◽  
Reliability Calculation

By using gray theory model, the problem with less data and poor information is easy to be solved. Thus, the grey theory and the reliability assessment method were connected to analyze the mechanism motion. At first, the concept and model of mechanism’s grey movement reliability were presented. And then, from the limit state equations of a mechanism’s moving function and kinematic accuracy, the gray reliability calculation formulas were deduced. Finally, combined with two examples the method was applied to the actual reliability analysis. The results show that the method is feasible and efficient, so it is practical to apply the grey reliability model in mechanism reliability analysis.

Application of Grey System Theory in the Dynamic Monitoring of Bridge

2014 ◽  
Vol 501-504 ◽  
pp. 829-833
Author(s):  
Cheng Xin Yu ◽  
Zheng Wen Yu ◽  
Yong Qian Zhao ◽  
Jia Dong Zhang
Keyword(s):  
Dynamic Deformation ◽  
Active Role ◽  
Theory Model ◽  
Grey System Theory ◽  
Dynamic Monitoring ◽  
Grey Theory ◽  
Observation Error ◽  
Bridge Structure ◽  
Grey System ◽  
Safety And Reliability

It has great significance to ensure the safety of bridge structure by using information technology to monitor the bridge dynamic deformation and find out problems in time, besides, it is more effective to make analysis of the bridge by using grey theory model. The combination of the two methods could avoid the observation error, and play an active role in improving the safety and reliability of bridge.

A Study of the Prediction of Load-Settlement Curves of Bored Piles with an Improved Grey Model

2013 ◽  
Vol 671-674 ◽  
pp. 3-9 ◽  
Author(s):  
Cheng Hua Wang ◽  
Mei Na Zhang
Keyword(s):  
Theory Model ◽  
Grey Model ◽  
System Model ◽  
Engineering Practice ◽  
Grey Theory ◽  
Grey System ◽  
Loading Tests ◽  
Bored Piles ◽  
Grey System Model

An improved grey system model GM(1,1) was proposed in this paper, considered that the large difference between predicted results and measured load-settlement relationship results of bored piles, in which the prediction results were given by the original theory. The complete and incomplete load-settlement curves from pile loading tests were fitted and predicated by the improved grey model. The results calculated with empirical equations or methods in technical code for building pile foundations were compared with those predicted with the improved grey model. Analysis of a case study showed that the results predicted by the improved grey theory model GM(1,1) had higher precision, which demostrated that this improved theory was of significance in engineering practice.

scholarly journals Reliability on timber columns under fire situation

Fire Research ◽  
2018 ◽  
Author(s):  
Auro Cândido Marcolan Júnior ◽  
Poliana Dias de Moraes
Keyword(s):  
Reliability Analysis ◽  
Cross Section ◽  
Structural Reliability ◽  
Rectangular Cross Section ◽  
Limit State ◽  
Random Variable ◽  
State Equations ◽  
Reduced Cross Section ◽  
Reliability Method ◽  
In Fire

Timber structures in fire situation are subject to intrinsic uncertainties from the material and the actions on the structure and their probabilistic behavior has not being studied exhaustively. In this paper, four limit state equations using the reduced cross-section method are developed for timber columns in fire situation. The security criteria taken into account in these equations are the compression, the lateral stability and the combined bending and compression, according to the NBR 7190:1997 standard. The structural reliability analysis of five simply supported timber columns with rectangular cross-section in fire situation and different base and height ratios where performed using the first order reliability method. The overall probability of failure of the column was obtained by associating the failure criteria in a series system. The reliability behavior of the different base to height ratios was evaluated, leading to different results for the distinct ratios and the criteria used. Also, a sensitivity analysis was performed indicating the timber charring rate as the most important random variable in the reliability analysis for these limit state equations.

Reliability Analysis of Arch Dam Considering Temperature Change Field

2012 ◽  
Vol 226-228 ◽  
pp. 1332-1337
Author(s):  
Ming Zhu Yang ◽  
Qing Xi Wu ◽  
Jun Lu
Keyword(s):  
Reliability Analysis ◽  
Temperature Change ◽  
Water Pressure ◽  
Limit State ◽  
Complex Structure ◽  
Temperature Drop ◽  
Random Variable ◽  
Arch Dam ◽  
State Equations ◽  
Tension And Compression

The loads on the arch dam and the materials physical properties of the dam and the bedrock are uncertain, and can be described with random variable. Due to the huge volume, the complex structure of the dam and excessive random variable, the reliability analysis of the dam is difficult. The dam is a higher order statically indeterminate structure, and the variation of the temperature obviously affects the stress and displacement of the structure, therefore, it is very important to consider the randomness of the temperature change load in the reliability analysis of arch dam. Based on the analysis of the stable temperature field, temperature rise and temperature drop field of the dam, the calculation method of temperature change field is further studied and applied in the reliability analysis of the arch dam. Considering random variables such as temperature change, water pressure, elastic modulus and strength of the materials, the stress and displacement of the arch dam and bedrock are calculated with a three dimensional finite element method, the limit state equations are established by RSM. Then the tension and compression reliability of the arch dam are analyzed using gradient optimization method. The results indicate that the temperature change field significantly influences the tension and compression reliability of the dam, and should be seriously considered in the reliability analysis of arch dams.

Study on Deformation Prediction of Landslide Based on Grey Theory and BP Neural Network

2012 ◽  
Vol 204-208 ◽  
pp. 520-525 ◽  
Author(s):  
Rong Yu Li ◽  
Yong Fen Ruan ◽  
Shi Sheng Li ◽  
Yong Hong Wu
Keyword(s):  
Neural Network ◽  
System Theory ◽  
Bp Neural Network ◽  
Theory Model ◽  
Grey System Theory ◽  
Practical Significance ◽  
Grey Theory ◽  
Grey System ◽  
Engineering Project ◽  
Landslide Deformation

The stability of the landslide can be effectively evaluated and predicted by predicting the future development of landslide deformation according to the actual deformation of the landslide. Therefore, the accuracy of the prediction regarding the landslide deformation determines the validity of the landslide stability assessment. The GM (1.1) model in the grey system theory, uses displacement time series to establish the grey differential equation. By solving the equation, we can obtain a time response function, which can then be used to predict the landslide deformation. The BP neural network is a used for training and exercising on the deformed samples. After the error meets the requirement, we can then use the trained model to predict the landslide deformation. This paper use both grey system theory model and BP neural network model to predict Jinlong ditch application field landslide deformation.The prediction results are compared and analyzed to test the accuracy of these two predictions. Finding a more accurate prediction method for application in actual engineering project has practical significance.

scholarly journals Reliability analysis of a prestressed bridge beam designed in serviceability limit state as recommended by NBR 6118 and 7188

2020 ◽  
Vol 13 (2) ◽  
pp. 380-397
Author(s):  
P. H. C. DE LYRA ◽  
A. T. BECK ◽  
F. R. STUCCHI
Keyword(s):  
Reliability Analysis ◽  
Reliability Index ◽  
Limit State ◽  
Economic Losses ◽  
Allowable Stress ◽  
State Equations ◽  
First Order ◽  
Serviceability Limit State ◽  
Reliability Method ◽  
Brazilian Standard

Abstract Nowadays it is known that it is important to study the safety of structures to avoid tragic accidents or economic losses. The most widely used method in the world to evaluate the safety of structures is structural reliability. The reliability index of prestressed precast beams of bridges designed using Brazilian standards (NBR6118 and NBR7188) is not known. This work evaluates the annual reliability indexes of a prestressed precast beam bridge at the serviceability limit state (SLS) projected using the Brazilian standard and compares it with results from the literature. The studied bridge has 33.5 meters of span, is simply supported, constituted by five precast concrete beams with U section. The reliability analysis was carried out using two methods for the four limit state equations: First Order Mean Value (FOMV) and First Order Reliability Method (FORM). Sensitivity analyzes were performed to consider both the relative contribution of these variables and the effect of their distributions on the annual reliability indexes for SLS. It was verified that the effect of load trains and the allowable stress significantly reduce the reliability index obtained for Brazilian standard. The service limit state equations are particularly sensitive to load trains, allowable stress and prestress losses, as well as their respective distributions.

scholarly journals An Efficient Time-Variant Reliability Analysis Method with Mixed Uncertainties

Algorithms ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 229
Author(s):  
Fangyi Li ◽  
Yufei Yan ◽  
Jianhua Rong ◽  
Houyao Zhu
Keyword(s):  
Reliability Analysis ◽  
Limit State ◽  
Random Variables ◽  
Equivalent Model ◽  
Independent Random Variables ◽  
Problem Analysis ◽  
Analysis Method ◽  
Calculation Algorithm ◽  
Reliability Problem ◽  
Interval Variables

In practical engineering, due to the lack of information, it is impossible to accurately determine the distribution of all variables. Therefore, time-variant reliability problems with both random and interval variables may be encountered. However, this kind of problem usually involves a complex multilevel nested optimization problem, which leads to a substantial computational burden, and it is difficult to meet the requirements of complex engineering problem analysis. This study proposes a decoupling strategy to efficiently analyze the time-variant reliability based on the mixed uncertainty model. The interval variables are treated with independent random variables that are uniformly distributed in their respective intervals. Then the time-variant reliability-equivalent model, containing only random variables, is established, to avoid multi-layer nesting optimization. The stochastic process is first discretized to obtain several static limit state functions at different times. The time-variant reliability problem is changed into the conventional time-invariant system reliability problem. First order reliability analysis method (FORM) is used to analyze the reliability of each time. Thus, an efficient and robust convergence hybrid time-variant reliability calculation algorithm is proposed based on the equivalent model. Finally, numerical examples shows the effectiveness of the proposed method.

Explosion Recurrence Modelling

2004 ◽  
Author(s):  
Sirous F. Yasseri ◽  
Jake Prager
Keyword(s):  
Risk Assessment ◽  
Goodness Of Fit ◽  
Residential Buildings ◽  
Limit State ◽  
Life Time ◽  
Assessment Method ◽  
The North ◽  
Offshore Installations ◽  
Risk Assessment Method ◽  
Explosion Load

This paper describes a recurrence law for explosions. The proposed recurrence law fits quite well to the historic explosion data in residential buildings as well as to the data on offshore installations in the North Sea. Generally quantified explosion risk assessment is performed for offshore installations, since it is believed historic data does not correspond to a specific installation and it may not be appropriate for use in performance based explosion engineering, which may in itself require realistic load description of explosion recurrence. The goodness-of-fit of the model for explosion occurrence data obtained using the quantified risk assessment method is also discussed. The paper then introduces the concept of performance-based design, which is an attempt to design structures with predictable performance under explosion loading. Performance objectives such as life safety, collapse prevention, or immediate resumption of operation are used to define the state of an installation following a design explosion. The recurrence law is then used to associate a level of explosion load to each limit state using a desirable level of probability of exceedance during the installations life time.

Response surface method strategies coupled with NLFEA for structural reliability analysis of prestressed bridges

2021 ◽  
Author(s):  
Silvia J. Sarmiento Nova ◽  
Jaime Gonzalez-Libreros ◽  
Gabriel Sas ◽  
Rafael A. Sanabria Díaz ◽  
Maria C. A. Texeira da Silva ◽  
...  
Keyword(s):  
Reliability Analysis ◽  
Response Surface ◽  
Response Surface Method ◽  
Structural Reliability ◽  
Limit State ◽  
Material Behavior ◽  
Nonlinear Material ◽  
State Function ◽  
Surface Method ◽  
Highly Nonlinear

<p>The Response Surface Method (RSM) has become an essential tool to solve structural reliability problems due to its accuracy, efficacy, and facility for coupling with Nonlinear Finite Element Analysis (NLFEA). In this paper, some strategies to improve the RSM efficacy without compromising its accuracy are tested. Initially, each strategy is implemented to assess the safety level of a highly nonlinear explicit limit state function. The strategy with the best results is then identified and used to carry out a reliability analysis of a prestressed concrete bridge, considering the nonlinear material behavior through NLFEA simulation. The calculated value of &#120573; is compared with the target value established in Eurocode for ULS. The results showed how RSM can be a practical methodology and how the improvements presented can reduce the computational cost of a traditional RSM giving a good alternative to simulation methods such as Monte Carlo.</p>

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