scholarly journals Investigation on the Mathematical Relation Model of Structural Reliability and Structural Robustness

2021 ◽  
Vol 26 (2) ◽  
pp. 26
Author(s):  
Qi-Wen Jin ◽  
Zheng Liu ◽  
Shuan-Hai He
Keyword(s):  
Structural Damage ◽  
Structural Reliability ◽  
Relational Model ◽  
Engineering Practice ◽  
Variation Trend ◽  
Evaluation Indexes ◽  
Structural Robustness ◽  
Mathematical Relation ◽  
Relation Model ◽  
Random Variation

Structural reliability and structural robustness, from different research fields, are usually employed for the evaluative analysis of building and civil engineering structures. Structural reliability has been widely used for structural analysis and optimization design, while structural robustness is still in rapid development. Several dimensionless evaluation indexes have been defined for structural robustness so far, such as the structural reliability-based redundancy index. However, these different evaluation indexes are usually based on subjective definitions, and they are also difficult to put into engineering practice. The mathematical relational model between structural reliability and structural robustness has not been established yet. This paper is a quantitative study, focusing on the mathematical relation between structural reliability and structural robustness so as to further develop the theory of structural robustness. A strain energy evaluation index for structural robustness is introduced firstly by considering the energy principle. The mathematical relation model of structural reliability and structural robustness is then derived followed by a further comparative study on sensitivity, structural damage, and random variation factor. A cantilever beam and a truss beam are also presented as two case studies. In this study, a parabolic curve mathematical model between structural reliability and structural robustness is established. A significant variation trend for their sensitivities is also observed. The complex interaction mechanism of the joint effect of structural damage and random variation factor is also reflected. With consideration of the variation trend of the structural reliability index that is affected by different degrees of structural damage (mild impairment, moderate impairment, and severe impairment), a three-stage framework for structural life-cycle maintenance management is also proposed. This study can help us gain a better understanding of structural robustness and structural reliability. Some practical references are also provided for the better decision-making of maintenance and management departments.

scholarly journals Structural Damage Identification Based on Integrated Utilization of Inverse Finite Element Method and Pseudo-Excitation Approach

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 606
Author(s):  
Tengteng Li ◽  
Maosen Cao ◽  
Jianle Li ◽  
Lei Yang ◽  
Hao Xu ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Structural Damage ◽  
Damage Identification ◽  
Displacement Measurement ◽  
Engineering Practice ◽  
Position Measurement ◽  
Inverse Finite Element Method ◽  
Pseudo Excitation ◽  
Element Method

The attempt to integrate the applications of conventional structural deformation reconstruction strategies and vibration-based damage identification methods is made in this study, where, more specifically, the inverse finite element method (iFEM) and pseudo-excitation approach (PE) are combined for the first time, to give rise to a novel structural health monitoring (SHM) framework showing various advantages, particularly in aspects of enhanced adaptability and robustness. As the key component of the method, the inverse finite element method (iFEM) enables precise reconstruction of vibration displacements based on measured dynamic strains, which, as compared to displacement measurement, is much more adaptable to existing on-board SHM systems in engineering practice. The PE, on the other hand, is applied subsequently, relying on the reconstructed displacements for the identification of structural damage. Delamination zones in a carbon fibre reinforced plastic (CFRP) laminate are identified using the developed method. As demonstrated by the damage detection results, the iFEM-PE method possesses apparently improved accuracy and significantly enhanced noise immunity compared to the original PE approach depending on displacement measurement. Extensive parametric study is conducted to discuss the influence of a variety of factors on the effectiveness and accuracy of damage identification, including the influence of damage size and position, measurement density, sensor layout, vibration frequency and noise level. It is found that different factors are highly correlated and thus should be considered comprehensively to achieve optimal detection results. The application of the iFEM-PE method is extended to better adapt to the structural operational state, where multiple groups of vibration responses within a wide frequency band are used. Hybrid data fusion is applied to process the damage index (DI) constructed based on the multiple responses, leading to detection results capable of indicating delamination positions precisely.

Causes of Structural Failures with Steel Structures

2017 ◽  
Author(s):  
Goran Alpsten
Keyword(s):  
Structural Damage ◽  
Human Error ◽  
Structural Reliability ◽  
Steel Structures ◽  
Fatigue Loading ◽  
Structural Instability ◽  
Human Errors ◽  
Collapse Mode ◽  
Load Carrying ◽  
Structural Failures

This paper is based on the experience from investigating over 400 structural collapses, incidents and serious structural damage cases with steel structures which have occurred over the past four centuries. The cause of the failures is most often a gross human error rather than a combination of “normal” variations in parameters affecting the load-carrying capacity, as considered in normal design procedures and structural reliability analyses. Human errors in execution are more prevalent as cause for the failures than errors in the design process, and the construction phase appears particularly prone to human errors. For normal steel structures with quasi-static (non-fatigue) loading, various structural instability phenomena have been observed to be the main collapse mode. An important observation is that welds are not as critical a cause of structural steel failures for statically loaded steel structures as implicitly understood in current regulations and rules for design and execution criteria.

Reliability analysis for a hypersonic aircraft’s wing spar

2019 ◽  
Vol 91 (4) ◽  
pp. 549-557
Author(s):  
Yuhui Wang ◽  
Peng Shao ◽  
Qingxian Wu ◽  
Mou Chen
Keyword(s):  
Reliability Analysis ◽  
Structural Reliability ◽  
Strength Degradation ◽  
Structural Safety ◽  
Engineering Practice ◽  
Flight Safety ◽  
Content Type ◽  
Hypersonic Aircraft ◽  
Analysis Scheme ◽  
Wing Spar

Purpose This paper aims to present a novel structural reliability analysis scheme with considering the structural strength degradation for the wing spar of a generic hypersonic aircraft to guarantee flight safety and structural reliability. Design/methodology/approach A logarithmic model with strength degradation for the wing spar is constructed, and a reliability model of the wing spar is established based on stress-strength interference theory and total probability theorem. Findings It is demonstrated that the proposed reliability analysis scheme can obtain more accurate structural reliability and failure results for the wing spar, and the strength degradation cannot be neglected. Furthermore, the obtained results will provide an important reference for the structural safety of hypersonic aircraft. Research limitations/implications The proposed reliability analysis scheme has not implemented in actual flight, as all the simulations are conducted according to the actual experiment data. Practical implications The proposed reliability analysis scheme can solve the structural life problem of the wing spar for hypersonic aircraft and meet engineering practice requirements, and it also provides an important reference to guarantee the flight safety and structural reliability for hypersonic aircraft. Originality/value To describe the damage evolution more accurately, with consideration of strength degradation, flight dynamics and material characteristics of the hypersonic aircraft, the stress-strength interference method is first applied to analyze the structural reliability of the wing spar for the hypersonic aircraft. The proposed analysis scheme is implemented on the dynamic model of the hypersonic aircraft, and the simulation demonstrates that a more reasonable reliability result can be achieved.

Temperature effect on electromechanical admittance–based concrete structural health monitoring

2019 ◽  
Vol 19 (3) ◽  
pp. 661-692 ◽  
Author(s):  
Demi Ai ◽  
Chengxing Lin ◽  
Hui Luo ◽  
Hongping Zhu
Keyword(s):  
Numerical Analysis ◽  
Structural Health Monitoring ◽  
Damage Detection ◽  
Temperature Effect ◽  
Health Monitoring ◽  
Structural Damage ◽  
Shield Tunnel ◽  
Engineering Practice ◽  
Damage Evaluation ◽  
Structural Health

Concrete structures in service are often subjected to environmental/operational temperature effects, which change their inherent properties and also inflict a challenge to their extrinsic monitoring systems. Recently, piezoelectric lead zirconate titanate (PZT)-based electromechanical admittance technique has been increasingly growing into an effective tool for concrete structural health monitoring; however, uncertainty in the changes of monitoring signals induced by temperature impact on concrete/PZT sensor would inevitably cause interference to structural damage detection, which adversely hinder its application from laboratory to engineering practice. This article, aiming at exploring the temperature effect on the electromechanical admittance–based concrete damage evaluation, primarily covered a series of theoretical/numerical analysis with rigorously experimental verifications. Three aspects of comparative studies were performed in theoretical/numerical analysis: (1) thermal-dependent parameters were inclusively evaluated in contribution to the electromechanical admittance characteristics via PZT-structure interaction models; (2) three-dimensional finite element analysis in multi-physics coupled field was employed to qualitatively assess the singular temperature effect on the electromechanical admittance behaviors of free-vibrated PZT, surface-bonded PZT/inside-embedded PZT coupled healthy concrete cubes; and (3) depending on the modeling of surface-bonded PZT-/inside-embedded PZT-cracked concrete cube, thermal effect on damage evaluation was addressed via quantification on the electromechanical admittance variations. In the experimental study, rigorous validation tests were carried out on a group of lab-scale concrete cubes, where surface-bonded PZT/inside-embedded PZT transducers were simultaneously employed for electromechanical admittance monitoring in view of thermal difference between concrete surface and its inner part. Correlation coefficient deviation value-based effective frequency shifts algorithm was also employed to compensate the temperature effect. Moreover, temperature effect was further testified on the monitoring of a full-scale shield-tunnel segment structure. Experimental results indicated that temperature triggered different behaviors of electromechanical admittance signatures for surface-bonded PZT/inside-embedded PZT transducers and contaminated the electromechanical admittance responses for damage detection. Structural damage severity level can be disadvantageously amplified by temperature increment even if under the same damage scenarios.

scholarly journals Fuzzy Damage Analysis of the Seismic Response of a Long-Distance Pipeline under a Coupling Multi-Influence Domain

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 62 ◽  
Author(s):  
Peng Zhang ◽  
Yihuan Wang ◽  
Guojin Qin
Keyword(s):  
Structural Damage ◽  
Structural Reliability ◽  
Dimensional Space ◽  
Space Time ◽  
Response Analysis ◽  
Seismic Load ◽  
Long Distance ◽  
Analysis And Design ◽  
Pressure Pipeline ◽  
The Impact

For a long-distance pipeline, the seismic load is a four-dimensional space-time excitation that simultaneously changes with time and space. In this work, a novel random space-time seismic model is established for a long-distance pipeline, which uses the Clough-Penzien model based on a random process and model of a random field. The response analysis of a long-distance pipeline for multipoint excitation and a buried pressure pipeline are established, while the stress analysis of the buried pressure pipeline is carried out in combination with von Mises theory. In addition, we consider the impact of the site type. The application of the proposed methodology is proved through numerical simulation. A fuzzy damage model and fuzzy safety criteria are established to assess the degree of the structure. The results indicate that a reasonable assessment and design method should consider the coupling multi-influence domain. In particular, evaluation of the structural damage should be done to establish fuzzy damage models and fuzzy safety criteria. The effective measurement of the uncertainty of such parameters forms an important basis for subsequent structural reliability analysis and design.

Study on Stability of Rock at Reservoir Banks Slop Based on AHP

2012 ◽  
Vol 204-208 ◽  
pp. 2309-2317 ◽  
Author(s):  
Zhi Jun Zhou ◽  
Han Liang ◽  
Xiao Dong Wang
Keyword(s):  
Slope Stability ◽  
Set Theory ◽  
Fuzzy Set ◽  
Fuzzy Set Theory ◽  
Engineering Practice ◽  
Stability Evaluation ◽  
Analytic Hierarchy ◽  
Evaluation Indexes ◽  
Comprehensive Evaluations ◽  
Research On Application

The paper aims to present the authors’ research on application of engineering fuzzy set theory analysis to reservoir ranks rock slop stability evaluation by using analytic hierarchy processing (AHP). Many methods, which used to analysis highway slope stability, are compared in the paper. On the basis of research on the general slope stability evaluation methods, lots of fuzzy factors of stability evaluation for highway slope are researched and fuzzy comparison matrix model is established. Correspondence relationship between mood operator and fuzzy value are determined. Evaluation indexes and grading standards are identified on the basis of engineering practice. The weight of every index is obtained by using analytic hierarchy processing and the method of Ridge-type distribution, which the method of combining with the bigger the more excellent and the smaller the more excellent. Engineering fuzzy set theory is used to make a comprehensive evaluations, overall evaluation of the highway slope stability is obtained according to the principle of maximum degree of subjection and the result of subjection degree vector. Slope stability evaluation of AN-SHAN Expressway is analyzed with analytical hierarchy process. Evaluation results provide a basis for the progress of the project, and the project carried out smoothly with the guidance of it. The results show that the model makes slope stability evaluation more comprehensive, scientific and rational.

scholarly journals A Sensitivity-Based Approach for Reliability Analysis of Randomly Excited Structures With Interval Axial Stiffness

2020 ◽  
Vol 6 (4) ◽  
Author(s):  
Alba Sofi ◽  
Giuseppe Muscolino ◽  
Filippo Giunta
Keyword(s):  
Reliability Analysis ◽  
Interval Analysis ◽  
Structural Reliability ◽  
Reliability Function ◽  
Extreme Value ◽  
Axial Stiffness ◽  
Engineering Practice ◽  
Stress Process ◽  
Rational Series ◽  
Interval Reliability

Abstract Reliability assessment of linear discretized structures with interval parameters subjected to stationary Gaussian multicorrelated random excitation is addressed. The interval reliability function for the extreme value stress process is evaluated under the Poisson assumption of independent up-crossing of a critical threshold. Within the interval framework, the range of stress-related quantities may be significantly overestimated as a consequence of the so-called dependency phenomenon, which arises due to the inability of the classical interval analysis to treat multiple occurrences of the same interval variables as dependent ones. To limit undesirable conservatism in the context of interval reliability analysis, a novel sensitivity-based procedure relying on a combination of the interval rational series expansion and the improved interval analysis via extra unitary interval is proposed. This procedure allows us to detect suitable combinations of the endpoints of the uncertain parameters which yield accurate estimates of the lower bound and upper bound of the interval reliability function for the extreme value stress process. Furthermore, sensitivity analysis enables to identify the most influential parameters on structural reliability. A numerical application is presented to demonstrate the accuracy and efficiency of the proposed method as well as its usefulness in view of decision-making in engineering practice.

scholarly journals Reliability basis for assessment of existing building structures with reference to sans 10160

2021 ◽  
Vol 63 (1) ◽  
Author(s):  
M Holický ◽  
J V Retief ◽  
C Viljoen
Keyword(s):  
South Africa ◽  
Alternative Assessment ◽  
Structural Reliability ◽  
Background Information ◽  
Design Stage ◽  
Engineering Practice ◽  
Building Structures ◽  
Design Standards ◽  
Structural Assessment ◽  
Existing Building

The principles of structural reliability are firmly established to provide the basis for structural performance as incorporated in design standards. Reliability-based procedures provide for variabilities and uncertainties that could reasonably be expected during the design service life of the structure. However, not all possible conditions to which all structures are exposed during such an extended service period can be accounted for effectively and economically at the design stage. The assessment of the reliability performance of an existing structure therefore forms an integral part of structural management and engineering practice. Despite the lag between the development and implementation of a basis for design and assessment of structures, the extensive body of information on structural assessment progresses steadily towards standardisation. This paper provides a review of the progress to provide background information towards extending the scope of South African structural standards to include guidance on structural assessment. The focus is on such developments to include provisions for existing structures in Eurocode, together with related investigations. In addition to a general review of background investigations, interrelationships between the basis of design and assessment for Eurocode (potentially also for South Africa) are considered. The main elements of a standardised basis for assessment are defined, and alternative assessment approaches are presented and demonstrated by representative examples. In conclusion, an outline of a possible development path for implementation in South Africa is provided.

Relative Distance Measure Model for the Fuzzy Synthetic Evaluation of Subgrade Stability in Seasonal Frozen Area

2012 ◽  
Vol 178-181 ◽  
pp. 1213-1217
Author(s):  
Han Bing Liu ◽  
Yi Ming Xiang ◽  
Hui Wang ◽  
Yan Yi Sun
Keyword(s):  
Structural Reliability ◽  
Distance Measure ◽  
Simulation Method ◽  
Relative Distance ◽  
Fuzzy Synthetic Evaluation ◽  
Interval Numbers ◽  
Evaluation Indexes ◽  
Measure Model ◽  
Grading Standards ◽  
Synthetic Evaluation

Based on the fuzziness and uncertainty of the subgrade stability in seasonal frozen area, the relative distance measure model with evaluation indexes and weights in the form of interval numbers is presented for the fuzzy synthetic evaluation of the subgrade stability. Firstly, the relative distance measure of each single index between the evaluated subgrade stability and the grading standards is defined. Then, the fuzzy synthetic evaluation model, which considers the functionality and proportionality of evaluation indexes, is established to calculate the comprehensive relative distance measure by using the Monte Carlo simulation method and the sequential relation analysis. Finally, a new decision index of the comprehensive relative distance measure is defined considering the concept of structural reliability, and the stability grade of seasonal frost soil subgrade can be determined by the minimum decision index from the corresponding grading standards. A practical example is given to demonstrate the feasibility and practicability of the proposed model.

Study on Crack Component Fatigue Life Analysis Based on SIF Fitting

2012 ◽  
Vol 229-231 ◽  
pp. 656-660
Author(s):  
Yan Chen ◽  
Yuan Tao Sun
Keyword(s):  
Fatigue Life ◽  
Crack Length ◽  
Infinite Plate ◽  
Mathematical Expression ◽  
Large Error ◽  
Engineering Practice ◽  
Type I ◽  
Mathematical Relation ◽  
Fatigue Life Analysis ◽  
Component Shape

The present structure crack analysis method simplifies the crack as type I crack, and put the stress intensity factor (SIF) mathematical expression of infinite plate under the bi-directional even stress load into Paris formula to analyse the fatigue life of crack components. Due to the finiteness and complexity of component shape and the nonuniformity of the stress distribution in the engineering practice, which makes the SIF value inaccuracy according to the present method, so that the result of crack fatigue life has a large error. Considering the shortcomings of the method, this paper offers a new method which is using the finite element method to calculate SIF in different crack length directly. By means of function fitting, this method determines the mathematical relation between SIF and the crack length and changes the form of Paris formula based on the relation. Furthermore, it can analyse the fatigue life of crack components and improve the analysis accuracy theoretically.

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