Implementing statistical fitting and reliability analysis for geotechnical engineering problems in R

Author(s):  
Xing Zheng Wu
Author(s):  
Qian Wang

Probabilistic analysis of practical engineering problems has long been based on traditional sampling-based approaches, such as Monte Carlo Simulations (MCS) and gradient-based first-order and second-order methods. Since the finite element (FE) or other numerical methods are required to evaluate engineering system responses, such as forces or displacements, it is not efficient to directly integrate FE and sampling-based analysis approaches. Over the years, various approximate methods have been developed and applied to the reliability analysis of engineering problems. In this study, an efficient model reduction technique based on high-dimensional model reduction (HDMR) method has been developed using augmented radial basis functions (RBFs). The basic idea is to use augmented RBFs to construct HDMR component functions. The first-order HDMR model only requires sample points along each variable axis. The HDMR model, once created and used to explicitly express a performance function, is further combined with MCS to perform probabilistic calculations. As test problems, a mathematical problem and a 10-bar truss example are studied using the proposed reliability analysis approach. The proposed method works well, and accurate reliability analysis results are found with a small number of original performance function evaluations, i.e., FE simulations.


Author(s):  
Zhe Zhang ◽  
Chao Jiang ◽  
G. Gary Wang ◽  
Xu Han

Evidence theory has a strong ability to deal with the epistemic uncertainty, based on which the uncertain parameters existing in many complex engineering problems with limited information can be conveniently treated. However, the heavy computational cost caused by its discrete property severely influences the practicability of evidence theory, which has become a main difficulty in structural reliability analysis using evidence theory. This paper aims to develop an efficient method to evaluate the reliability for structures with evidence variables, and hence improves the applicability of evidence theory for engineering problems. A non-probabilistic reliability index approach is introduced to obtain a design point on the limit-state surface. An assistant area is then constructed through the obtained design point, based on which a small number of focal elements can be picked out for extreme analysis instead of using all the elements. The vertex method is used for extreme analysis to obtain the minimum and maximum values of the limit-state function over a focal element. A reliability interval composed of the belief measure and the plausibility measure is finally obtained for the structure. Two numerical examples are investigated to demonstrate the effectiveness of the proposed method.


2011 ◽  
Vol 320 ◽  
pp. 20-25
Author(s):  
Wei Dong Pan ◽  
Ren Guo Gu ◽  
Ke Zhu ◽  
Yong Gang Lv

As an international general finite element analysis software, ABAQUS has super nonlinear analysis function and is playing an increasingly important role in the numerical calculation analysis of geotechnical engineering structures. CAE module of its own provides a certain amount of convenience for the beginners, but it is inadequate in the face of more complex geotechnical engineering problems. Based on parametric language PYTHON, using its modular model code, bypassing the CAE module, the ABAQUS finite element analysis calculated and analyzed the influence of ER on the CFG pile composite foundation settlement and pile side friction. Finite element analysis and the results show that: the process of ABAQUS finite element analysis, which is based on the parameter language PYTHON, is simple and has very high computational efficiency and accuracy in the analysis complex geotechnical engineering problems.


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