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Structural reliability assessment is of great significance for the safety and maintenance of structures. In recent years, the moment method has been rapidly developed and applied widespread for its simplicity and performance. Sometimes, the accuracy of the moment method, using only the first four moments (i.e., mean value, standard deviation, skewness, and kurtosis), is not sufficient in evaluating the reliability index of strong non-Gaussian performance functions. In this study, a method based on the quartic normal transformation (QNT) is proposed for structural reliability assessment, which enables incorporation of the first five moments, including the super-skewness, of performance function. The structural reliability index based on the QNT model is derived. The first five moments of the performance function are estimated by introducing the point estimate method. Seven engineering examples are employed to demonstrate the efficacy of the QNT. The results show that the computational efficiencies of CNT and QNT were close to each other and both superior to that of MCS. The results also show that the performance of QNT is superior to CNT in aspect of accuracy and robustness in particular to performance functions with strong non-Gaussianity. [ABSTRACT FROM AUTHOR]

The article is dedicated to problem of technical state assessment of real steel truss under operation for residual life prediction after technical investigation. The reliability index is calculated based on design, real and prospective loads. Method of statistical data analysis adopted for stress-strain determination also for all kinds of applied loads. The residual life with the reliability index determined as a transition from satisfactory to emergency technical state. The method provides the possibility for estimation of future safety steel structures operation witreliability index; residual life; steel truss; technical stateh technical investigation results only that exclude any subjective opinion. [ABSTRACT FROM AUTHOR]

Retaining walls are important structural systems used in the construction of highways. With asset management methods for retaining wall inventories lagging those developed for highway bridges, there is a need to develop risk management methods for these critical structural systems. A major challenge is the vast inventories of retaining walls that asset managers must manage and the inherent limitations of visual inspections. This study proposes an asset management framework for retaining walls based on risk assessments using structural monitoring data. First, a long-term wireless monitoring solution is proposed to measure wall tilt and strain over long periods of time. Second, an analytical framework is developed to separate wall thermal responses from lateral earth pressures responses with the latter used to extract estimated lateral earth pressure distributions. A statistical distribution of lateral earth pressures are used in a reliability assessment of the wall to provide a measure of failure probability that can be combined with failure consequences to estimate asset risk. To illustrate the proposed methodology, a reinforced concrete cantilever retaining wall panel is selected for long-term structural health monitoring. A wireless structural health monitoring system is installed to measure the tilt, strain, and temperature response of the wall continuously over 15 months. The study reveals the wall exhibits strong diurnal and seasonal variations offering insight into wall behavior under operational conditions. Hypothesized levels of corrosion in the steel reinforcement at the base of the wall are explored to estimate the wall reliability. Even under the assumption of 20% reinforcement section loss, the monitored wall was found to have a reliability index well above 3.0. [ABSTRACT FROM AUTHOR]

Analytical and numerical solutions for the problem of geosynthetic-reinforced fills over a void have been the subject of investigation for the last four decades. A common feature of this prior work is that all methods have treated the analytical solutions as deterministic. While the treatment of some input parameters must be taken as deterministic, there are other parameters that have uncertainty. Furthermore, the underlying mechanistic models for load and resistance terms in the limit state equations for the reinforced fill over a void problem can be expected to have different accuracy. This paper revisits the problem of geosynthetic-reinforced fills over voids from a probabilistic point of view for reinforcement tensile strain, tensile strength, and geosynthetic stiffness limit states. Particular attention is paid to the method used to select the isochronous stiffness of the reinforcement and the associated uncertainty in the magnitude of that value. The paper demonstrates how the factor of safety from deterministic past practice can be linked quantitatively to the reliability index used in contemporary probabilistic design. Finally, the paper demonstrates the advantage of using product-specific constant-load creep test results to maximise margins of safety for strength and stiffness limit states in both deterministic and probabilistic frameworks. [ABSTRACT FROM AUTHOR]

Due to the complexity of the transmission tower structure and the correlation between wind and ice loads in the actual project, it is difficult to analyze the reliability of transmission towers with traditional methods. To solve this problem, the unscented transformation (UT) principle is presented concisely and used in the reliability analysis of transmission towers in this paper. Moreover, the finite element model of the target transmission tower is created. The reliability indices of the transmission tower under various loading cases are evaluated using UT and analyzed relative to the outcomes of the Monte Carlo method (MCS). Lastly, by analyzing and validating a wine-cup shape tangent tower, the simulation results show that the UT yields reliability indices with less than 6% relative error compared with MCS results for the transmission towers with lower reliability, which are more important in engineering. Variations in error caused by the change in correlation coefficients among variables are small. Consequently, the efficiency of calculations is improved by the UT-based reliability calculations for transmission towers in the case of correlated variables, which better meet engineering application requirements. It is proved that the method of reliability analysis for transmission towers based on the UT is applicable. [ABSTRACT FROM AUTHOR]

The bearing capacity of strip footings is significantly influenced by uncertainties related to the footing, soil conditions, and load inclination. Given the inherent unpredictability in footing design, the reliability-based design of geotechnical structures has garnered considerable interest in the research community. This paper presents a state-of-the-art probabilistic design for footings under inclined loading using the first-order reliability method (FORM) combined with a hybrid least squares support vector machine (LSSVM) learning approach. A comprehensive dataset comprising 920 samples from the literature, with the reduction factor (RF) as the output parameter, was utilized to simulate hybrid LSSVM models based on particle swarm optimization (PSO) and Harris hawks optimization (HHO). The input variables for predicting the bearing capacity include the load eccentricity-to-width ratio, embedment ratio, load inclination-to-friction angle, and load arrangement. The performance metrics indicate that among the three proposed machine learning models, the LSSVM-PSO model achieves the best predictive performance, with an R2 of 0.991 and an RMSE of 0.051 during training and an R2 of 0.962 and an RMSE of 0.109 during testing. The model's performance was further evaluated via rank analysis, reliability analysis, regression plots, and uncertainty analysis. The reliability index (β) and corresponding probability of failure (POF) computed using FORM were compared with the actual values for both phases. The study concluded that the LSSVM-PSO is the most reliable method for reliability-based design, demonstrating superior performance and reliability. This hybrid approach offers a robust framework for addressing uncertainties in geotechnical engineering, enhancing the reliability and accuracy of footing design under inclined loading conditions. [ABSTRACT FROM AUTHOR]

There are different methods to assess the liquefaction potential of sandy soil sites. Meanwhile, the comparison of these methods in terms of the effect of soil heterogeneity and based on the system reliability index has received less attention. This study of sandy soil liquefaction potential using two different approaches, which are the standard penetration test (SPT) and shear wave velocity (Vs) have been analyzed stochastically. For this purpose, a real saturated site with ten heterogeneous soil layers and three boreholes was considered. The site was networking and SPT and Vs data in areas other than borehole's locations were predicted using the kriging method via a codded computer program in MATLAB. In the next step, each column of the assumed network is considered to be a borehole and using the predicted SPT-N and Vs data, and Monte Carlo Simulation (MCS) the reliability index of the system of the site by Sequential Compounding Method (SCM) were determined. The results show that for the assigned site the determined system reliability index using SPT-N data was larger than the Vs data which confirms that the SPT approach is more conservative. [ABSTRACT FROM AUTHOR]

Digital image correlation (DIC), a widely used non-contact measurement technique, often requires empirical tuning of several algorithmic parameters to strike a balance between computational accuracy and efficiency. This paper introduces a novel uncertainty analysis approach aimed at optimizing the parameter intervals of a DIC algorithm. Specifically, the method leverages the inverse compositional Gauss–Newton algorithm combined with a prediction-correction scheme (IC-GN-PC), considering three critical parameters as interval variables. Uncertainty analysis is conducted using a non-probabilistic interval-based multidimensional parallelepiped model, where accuracy and efficiency serve as the reliability indexes. To achieve both high computational accuracy and efficiency, these two reliability indexes are simultaneously improved by optimizing the chosen parameter intervals. The optimized algorithm parameters are subsequently tested and validated through two case studies. The proposed method can be generalized to enhance multiple aspects of an algorithm's performance by optimizing the relevant parameter intervals. [ABSTRACT FROM AUTHOR]

This paper presents a finite element analysis (FEA) of and reliability study on concrete-filled steel tube (CFST) members under the combined effects of corrosion and compressive loading. First, a stochastic-based FE model is established through the proposed secondary development program based on ABAQUS 2021 software. The model could account for the uncertainties of material, geometric, and corrosion effect on CFST members. The reliability of the built model was validated through experimental data of corroded CFST members under compression loading. Subsequently, the compressive performance of CFST under a combination of corrosion and loading was further investigated by numerical parameter analysis. A total of 1800 models were created to clarify the coupling mechanism among the core concrete strength, the steel tube strength, the steel ratio, and the maximum strength of the CFST member. Three theoretical formulas presented in classical design standards were used to calculate the axial compressive strength of the corroded CFST, and the uncertainty parameters μkp and δkp were also obtained for the discussed design formulas. Finally, the First Order and Second Moment (FOSM) method was employed to estimate the reliability indices β across different standards. The calculations revealed that the reliability indices β according to European standard ranges from 2.93 to 5.52, with some results falling below the target reliability index βT of 3.65. In addition, the multi-parameter coupling effects on reliability index β were investigated, and the main influencing factors were obtained. By leveraging the reliability analysis, reasonable design requirements can be proposed for CFST members under the coupling effects of corrosion and external load, which provides a design basis for the CFST member. [ABSTRACT FROM AUTHOR]

The estimation of the resistance factor in load and resistance factor design (LRFD) calibration for simple soil–structure limit states is most often based on model bias data of limited size. Frequently, the bias data are only available or required for the resistance term. In this study, the confidence in the estimate of the mean of the resistance factor is computed for the case of one resistance factor and one load factor where limited model bias data are available for both load and resistance terms. The bootstrap method is used to compute synthetic load and resistance bias data sets from which confidence intervals on the point (mean) estimate of the resistance factor and load factor are computed. A closed-form solution is used to calculate the resistance factor for a single prescribed load factor and target reliability index, bias data, and nominal load and resistance variables that are lognormally distributed. However, the approach is general using Monte Carlo simulation. The method is demonstrated using the case of the internal stability pullout limit state for steel strip mechanically stabilized earth walls. The example demonstrates the quantitative influence on pullout design using upper and lower 95% confidence interval limits for load and resistance factors. [ABSTRACT FROM AUTHOR]

This study characterizes the statistical uncertainties in the bivariate distribution of friction angle and cohesion of soils using bootstrap method and explores its application to the reliability‐based design of slopes. First, the bivariate distribution of friction angle and cohesion is modelled using the copula approach based on limited test data. Then, the statistical uncertainties in the derived bivariate distribution of friction angle and cohesion are characterized by the bootstrap method. Finally, an infinite slope is employed to investigate the impact of the statistical uncertainties in friction angle and cohesion on slope reliability. The reliability‐based designs of slopes based on the point and interval estimate of reliability index are compared. The results indicate that the bivariate distribution of friction angle and cohesion derived from limited test data exhibits large statistical uncertainties. The reliability index of the infinite slope shows visible variation because of the large statistical uncertainties in friction angle and cohesion. The reliability index of slopes considering the statistical uncertainties in friction angle and cohesion is presented as a confidence interval. The interval estimate of reliability index gives a more comprehensive description of slope reliability than the point estimate of reliability index. Furthermore, the reliability‐based design of slopes based on the interval estimate of reliability index can reflect the effect of the amount of test data on the design and link the site investigation efforts and investments on shear tests to final design savings. [ABSTRACT FROM AUTHOR]

Fibre-reinforced polymer (FRP) reinforcement has been employed as an alternative to conventional steel reinforcement in concrete structures, which is attributed to its excellent strength and corrosion resistance. However, one drawback is that FRP reinforcements are brittle and affect the ductility of concrete structures. One of the recent effective techniques proposed to overcome ductility issues is the compression yielding (CY) concept. The CY mechanism allows the structure to fail differently than the conventional FRP-reinforced concrete structure. Thus, the existing design recommendations as per the current codes for FRP-reinforced concrete structures are not appropriate. Hence, reliability studies are crucial for the development of a functional CY beam design in order to emphasise the structure's lifetime performance and to guarantee safety requirements. In this study, a reliability-based design approach is developed for a compression-yielded FRP-reinforced concrete beam (CY beam) using load and resistance factor design (LRFD). Firstly, the flexural failure modes of CY beams are discussed. The uncertainties involved in the development of the probabilistic model for the CY beam are defined. A case study is consequently conducted for a CY beam with random variables that are associated with the statistical characteristics of material properties and load. The reliability analysis method employed in this research is the Hasofer–Lind method. The results suggest the importance of choosing appropriate design variables and stochastic parameters for CY blocks that contribute to a higher level of reliability. The reliability index and resistance factors of a CY beam are then evaluated using the Monte Carlo Simulation computational method. The reliability index value of 3.336 is obtained from the simulation, which indicates that the CY beam demonstrates ductile behaviour. The results not only demonstrate ductile behaviour but also contribute to a possible reduction in material costs and a substantial safety margin. When compared to conventional FRP-reinforced concrete beams, for different load ratios, CY beams showed higher resistance and better reliability levels. [ABSTRACT FROM AUTHOR]

Background The study aimed to study the relative and absolute indicators of liver cancer (C22) in Kazakhstan over 10 years in the prism of a trend indicator (moving average), coefficient of variation (Cv), accounting reliability index (Idi).In 2022, in Kazakhstan, the incidence of liver cancer (C22) was 5.1 per 100 thousand people, mortality was 2.9, respectively, the index of reliability of accounting was 0.2.The unified risk of morbidity of the population of Kazakhstan with liver cancer for the period 2013-2022 amounted to 28.6%, mortality - 33.5%, respectively. Result Over the period 2013-2022, newly diagnosed liver cancer in Kazakhstan increased by 31%, the rate of decrease in the number of newly diagnosed liver cancers varied unevenly over the years, which demonstrates a high rate and amplitude of change from 105 to -140, which significantly complicates the prediction of this pathology. Conclusion: For the period 2013-2022, posthumously registered liver cancer consistently occupied the first place in the structure of specific gravity among all malignant neoplasms in Kazakhstan. [ABSTRACT FROM AUTHOR]

In engineering practice, liquefaction severity map is usually developed from liquefaction potential index (LPI) which is estimated using in-situ tests, such as cone penetration tests (CPTs). To efficiently perform in-situ tests for obtaining a reliable liquefaction severity map, it is advantageous to use adaptive sampling strategy, which uses results from initial measurements to sequentially decide CPT number and locations in a later stage. For example, the optimal number and locations of subsequent CPTs may be determined for maximising the reduction of overall uncertainty in the interpolated LPI data over the map obtained from a preliminary stage. However, uncertainty-based adaptive sampling might not provide optimal results for liquefaction severity mapping because the threshold of liquefaction severity classification is not considered. To properly evaluate the reliability of interpreted liquefaction severity map, a reliability index, $\beta$ β , is proposed in this study and further used to determine the optimal number and locations of in-situ tests. The proposed risk-informed adaptive sampling strategy is illustrated and compared with the uncertainty-based strategy. The example shows that the proposed method is more efficient than the uncertainty-based strategy. [ABSTRACT FROM AUTHOR]

The investigation introduces an advanced model procedure for evaluating the structural reliability of semi-rigid frame connections in existing aged buildings. Specifically, the focus is on the top angle and seat pad (TA–SP) semi-rigid connection, which was not initially considered in the current design standards. The approach employs a plastic hinge model to predict the ultimate strength of the connection and its beam-to-column behaviour. In order to increase computational efficiency, the investigation leverages the nonlinear behaviour of the finite element (FE) model to validate critical parameters. The statistical properties of the existing connection were obtained based on past experimental data, highlighting the weakest elements in the system. The first-order and second-order reliability methods and Monte Carlo simulations were employed to estimate the reliability index. Percentile errors were assessed to understand their impact on higher-order interactions. This new technique of identification quantifies the probability of the system failure interactions. Notably, a 45% lesser error aligns with the target reliability index, while a 114.5% larger error indicates a significant deviation from actual failure probability values. Each methodology introduced adheres to the current standard, and the system reliability analysis provides a vigorous conclusions scheme framework for assessing the existing TA–SP semi-rigid connection. [ABSTRACT FROM AUTHOR]

A probabilistic limit equilibrium framework combining empirical load transfer factor and anisotropy of soil cohesion is developed to conduct pile‐reinforced slope reliability analysis. The anisotropy of soil cohesion is determined conditioned on that the thrust force direction is parallel to the major principal direction and it is easily combined with load transfer factor, which are related with soil parameters, and pile parameters. The proposed method is illustrated against a homogeneous soil slope. The sensitivity studies of pile parameters on factor of safety (FS; calculated at respective means of soil parameters) and β demonstrated that the anisotropy of soil cohesion tends to pose significant effect on reliability index β than on FS. The effect of anisotropy of soil cohesion on FS is found to be slightly different under different pile locations, whereas its effect on β is observed to be least if piles are drilled at the middle part of slope and more significant effect is observed when piles are drilled at the lower and upper part of slope. The plots from the sensitivity studies provide an alternative tool for pile designs aiming at the target reliability index β. The proposed method contributes to the pile‐reinforced slope stability within limit equilibrium framework. [ABSTRACT FROM AUTHOR]

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For the purpose of reliability quantitative assessment of the surrounding rock of the deeply embedded karst tunnel and the geological body around the cavern in the case of the cavern in the forepart of the tunnel face, on the basis of the upper bound limit analysis method, the energy dissipation theory, as well as the reliability theory, the dimensionless performance function of each damage area of the deeply buried karst tunnels could be established in the case of the cavern in the front of the tunnel face. Subsequently, the probability of failure and the reliability index of each damage region of the deep–bedded karst tunnel in the case of the cavern in the front of this tunnel face should be calculated through the Monte Carlo simulation sampling approach. The investigation has demonstrated that the larger the cohesion of the geotechnical body and the larger the internal friction angle within the geotechnical body, the larger the reliability indexes of the geotechnical bodies around the tunnel. The larger the diameter of the cavern and the larger the tunnel burial depth, the greater the probability of failure in the left part of the geotechnical body around this cavern, and the smaller the reliability indexes of these damage areas. [ABSTRACT FROM AUTHOR]

Concrete confinement using fiber-reinforced polymers (FRPs) has been vastly used for strengthening of reinforced concrete (RC) columns. The strengthening of RC columns belongs to the realm of existing structures, which has been recognized as distinct from the design of new structures. Code development efforts for the strengthening of RC columns should follow a reliability-based framework similar to the one used in the code development for new structures. In this process, a number of additional issues arise: the mechanical model of FRP confinement representing existing RC columns, the statistical description of the design variables, and the target reliability to be attained. In this study, the reliability levels of 288 axially loaded, FRP-RC short columns of circular cross sections, strengthened according to ACI 440 guidelines, are assessed. Monte Carlo simulation is used in the probabilistic description of column strength and computation of the probability of failure. An FRP confinement model that explicitly accounts for the presence of transversal steel and attendant model errors associated to the estimation of ultimate stress and ultimate strain are used in the computation of the FRP-RC column capacity. The values of the reliability index are in the range of 3.92 to 4.61, satisfying the target reliability suggested for both new and existing structures. The research findings presented herein provide further support for the efforts of ACI Committee 440 in the development of standards related to the FRP strengthening of RC columns. [ABSTRACT FROM AUTHOR]

The level of electrical energy demand in an area reflects the welfare of that community. The greater the use of electrical energy, the higher the community's standard of living, followed by the public's critical attitude towards everything that happens and influences lives, including electricity services. Generally, a network's reliability level can be seen from the size of the SAIDI and SAIFI values on the PLN (state electricity company) side. The calculation and reliability analysis results of the Lhokseumawe ULP above show that the total SAIFI index value is 2.68 times/year. The SAIFI Rayon Lhokseumawe reliability index is categorized as reliable because its value does not exceed the standard set by PLN in SPLN 68-2 of 1986, namely 3.2 times/year. The total value of the SAIDI index is 45.30 hours/year. The Lhokseumawe Rayon SAIDI reliability index is categorized as unreliable because its value exceeds the standard set by PLN in SPLN 68-2 of 1986, namely 21 hours/year. There are certainly differences in infrastructure, electrical equipment, and number of customers in 1986 compared to current years; this has a different influence on electricity reliability values such as SAIDI and SAIFI.

Due to the complexity of the transmission tower structure and the correlation between wind and ice loads in the actual project, it is difficult to analyze the reliability of transmission towers with traditional methods. To solve this problem, the unscented transformation (UT) principle is presented concisely and used in the reliability analysis of transmission towers in this paper. Moreover, the finite element model of the target transmission tower is created. The reliability indices of the transmission tower under various loading cases are evaluated using UT and analyzed relative to the outcomes of the Monte Carlo method (MCS). Lastly, by analyzing and validating a wine-cup shape tangent tower, the simulation results show that the UT yields reliability indices with less than 6% relative error compared with MCS results for the transmission towers with lower reliability, which are more important in engineering. Variations in error caused by the change in correlation coefficients among variables are small. Consequently, the efficiency of calculations is improved by the UT-based reliability calculations for transmission towers in the case of correlated variables, which better meet engineering application requirements. It is proved that the method of reliability analysis for transmission towers based on the UT is applicable.

In this work, we performed a reliable study of the IEF model, which calculates the critical stress intensity factor, KIC, already studied in our previous article (Daoud et al. Int J Adv Manuf Technol 92:569–581, 2017), by the Phimeca-soft, where we performed a parametric study of the variation of the reliability index (β) as a function of the crack length (a) of the three states G1(x), G2(x) and G3(x) of the four sample types (R2, R4, R10 and R80), and also found the FORM/SORM results, as well as the histogram of elasticity of all variables used in the reliability study for the four sample types, with E26 galvanized sheet, safety and failure domains depending on the limit state used and importance of calculation variables on the reliability of the fracture. Then, the critical stress intensity factor (KIC) was found by the analytical method (IEF Model) equal to 63.13 MPa.m1/2 (accurate but not precise value), by the numerical method using the software Franc2D equal to 57.94 ± 4.29 MPa.m1/2 (precise but not accurate value) and by the reliability method using the software Phimeca-soft equal to 38.93 ± 0.83 MPa.m1/2 (accurate and precise value). [ABSTRACT FROM AUTHOR]

In this paper, a novel statistical vibration-based damage detection method is developed considering uncertainties in measured resonance frequencies. The proposed method is based on the application of resonance frequencies as the most accurate and easiest measurable vibration feature. For proof of efficiency of the proposed method, case studies were undertaken using two identical composite plates, one delaminated and the other pristine. In this respect, the frequency response functions (FRFs) were measured and used as the main input to the Resonance Detection Algorithm as the proposed method. Applying these FRFs to a Resonance Detector Function can determine the resonant frequencies and their statistical distribution. Through the statistical distributions of the corresponding resonant frequencies, their reliability of detecting damage has been obtained via the beta distribution. By observing the damage detection reliability of the two sets of corresponding resonant frequencies, it has been determined that the changes in natural frequencies are due to structural changes and not random errors through measurement. [ABSTRACT FROM AUTHOR]

Resistance factors (ϕ-factors) are reliability-based factors of safety used in load and resistance factor design (LRFD) of structural systems. The ϕ-factors specified in the consensus standard for the structural design of pultruded fiber-reinforced polymer (FRP) structural members and connections are generally lower than the ϕ-factors used for more conventional materials (e.g., structural steel, reinforced concrete, and wood) for comparable limit states, consequently potentially limiting the application of pultruded FRP as a structural material. This work describes a review of 350 published experimental tests of bolted connections in pultruded FRP and compares these test results with the nominal strengths from equations in the consensus standard. Subsequently, a first-order reliability method analysis—following the methodology proposed by Ellingwood for pultruded FRP composites—was performed to re-examine ϕ-factors for the most common limit states of bolted connections in pultruded FRP. All relevant limit states for bearing-type connections as defined by the consensus standard were considered in the study and the derived ϕ-factors were compared with the ϕ-factors prescribed in the consensus standard with the goal of highlighting the need for additional research. [ABSTRACT FROM AUTHOR]

In the context of this research, understanding the reliability of a power generator is essential as a criterion for assessing its suitability for use or the need for further development. The method used in this study is reliability analysis, known as "Expected Energy Not Supplied (EENS)." The initial step of this method is to calculate the FOR (Forced Outage Rate) to determine the level of disturbances in the generator unit. The subsequent process involves calculating individual probabilities, analyzing the generator load curve, determining the EENS values of three generators, and comparing them with the EENS standards established by the National Electricity Market. These standards stipulate that EENS should not exceed 0.002% of the total energy consumption in the region. This research marks a significant milestone as the first endeavour conducted on Lombok Island within this specific context. The study was conducted by analyzing three operational Micro-Hydro Power (MHP) units on Lombok Island. The research findings indicate that the EENS metric for MHP on Lombok Island stands at 2.822%. This result suggests that the reliability of MHP on Lombok Island falls below the established criterion, which is less than 0.002% annually. In practical terms, these findings imply that MHP plants located on Lombok Island may not be relied upon as the primary source to meet the electricity demands of the Lombok region in 2022. This research provides valuable insights into the challenges of energy reliability on Lombok Island and serves as a crucial foundation for further considerations in the development of renewable energy sources in the region. [ABSTRACT FROM AUTHOR]

With the increasing scale of the power system, the increasing penetration of renewable energy, and the increasing uncertainty factors, traditional reliability evaluation methods based on Monte Carlo simulation have greatly reduced computational efficiency in complex power systems and cannot meet the requirements of real-time and rapid evaluation. This article proposes a hybrid data-driven strategy to achieve a rapid assessment of power grid reliability on two levels: offline training and online evaluation. Firstly, this article derives explicit analytical expressions for reliability indicators and component parameters, avoiding the computational burden of repetitive Monte Carlo simulation. Next, a large number of samples are quickly generated by parsing expressions to train convolutional neural networks (CNNs), and the system reliability index is quickly calculated under changing operating conditions through CNNs. Finally, the effectiveness and feasibility of the proposed method are verified through an improved RTS-79 testing system. The calculation results show that the method proposed in this article can achieve an online solution of second-level reliability indicators while ensuring calculation accuracy. [ABSTRACT FROM AUTHOR]

Abstract A probabilistic limit equilibrium framework combining empirical load transfer factor and anisotropy of soil cohesion is developed to conduct pile‐reinforced slope reliability analysis. The anisotropy of soil cohesion is determined conditioned on that the thrust force direction is parallel to the major principal direction and it is easily combined with load transfer factor, which are related with soil parameters, and pile parameters. The proposed method is illustrated against a homogeneous soil slope. The sensitivity studies of pile parameters on factor of safety (FS; calculated at respective means of soil parameters) and β demonstrated that the anisotropy of soil cohesion tends to pose significant effect on reliability index β than on FS. The effect of anisotropy of soil cohesion on FS is found to be slightly different under different pile locations, whereas its effect on β is observed to be least if piles are drilled at the middle part of slope and more significant effect is observed when piles are drilled at the lower and upper part of slope. The plots from the sensitivity studies provide an alternative tool for pile designs aiming at the target reliability index β. The proposed method contributes to the pile‐reinforced slope stability within limit equilibrium framework.

The article is dedicated to problem of technical state assessment of real steel truss under operation for residual life prediction after technical investigation. The reliability index is calculated based on design, real and prospective loads. Method of statistical data analysis adopted for stress-strain determination also for all kinds of applied loads. The residual life with the reliability index determined as a transition from satisfactory to emergency technical state. The method provides the possibility for estimation of future safety steel structures operation with technical investigation results only that exclude any subjective opinion.

In power systems with a high proportion of renewable energy, to achieve coordinated optimal scheduling of source and load considering multiple uncertainties is an important issue in power system operation. Therefore, a probabilistic spinning reserve optimization model based on multiple scenarios is constructed. Multiple uncertain factors are considered in the model, such as wind power and solar power forecast errors, load forecast error and unscheduled generator outage. Renewable energy curtailment and load shedding are used as special reserve resources in the day-ahead security-constrained unit commitment (SCUC) to improve the economic operation efficiency. The calculations of reliability indexes, expected energy not served and expected energy curtailment, are simplified, and the inequality constraints related to these two indexes are reduced, which improves the computational performance of the model. The model optimizes the total expected cost considering multiple uncertainties. Case studies based on the IEEE-RTS demonstrate the effectiveness of the proposed model. The numerical results show that the improved calculation method of reliability indexes can effectively reduce the solution time of the SCUC model. The reserve optimization model can realize the dynamic allocation of the spinning reserve capacity of the system and improve economic operation of the system.

In line with the principles of modern design a building structure should not only be safe but also optimized. In deterministic optimization, the uncertainties of the structures are not explicitly taken into account. Traditionally, uncertainties of the structural system (i.e. material parameters, loads, dimensions of the cross-sections) are considered by means of partial safety factors specified in design codes. Worth noticing, that optimal structures are sensitive to randomness design parameters and deterministic optimal solutions may lead to reduced reliability levels. It therefore seems natural to extend the formulation of deterministic optimization with the random scatter of parameter values. Such a formulation is offered by robust optimization and reliability-based design optimization. The applicability ofRBDOis strongly dependent on the availability of the joint probability density function.Aformulation of non-deterministic optimization that better adapts to the design realities is robust optimization. Unlike RBDO optimization, this formulation does not require estimation of failure probabilities. In the paper using the examples of steel beams, the authors compare the strengths and weaknesses of both formulations.

This article presents the results of reinforcement cover thickness measurements carried out in several buildings erected in 2022 in Rzeszów. The results of the measurements are presented in two variants depending on the reinforcement cover thickness assumed by the designer: the first variant contains all the results and the second contains results only from places where the designed cover thickness was 25 mm. For both variants, a histogram of the percentage deviation from the design value was determined and mean values, standard deviation, coefficient of variation and maximum values of negative and positive deviation were calculated. The obtained reinforcement cover thickness distributions were used to determine the reliability of a floor slab with a simply supported beam static scheme. Analyses were carried out for 4 slabs differing in span, thickness and selected reinforcement. Using the FORM analytical method, values for the reliability index and probability of failure were determined. The reliability index values obtained were compared with the values required by EC 1990 and ISO 2394. The results obtained did not meet the standard requirements.

The Buffalo River catchment in KwaZulu-Natal, South Africa, has limited water resource infrastructure development, and climate change is predicted to increase its water supply deficits by exacerbating water distribution inequalities. This study evaluates and optimises current climate change policy plans on the Buffalo River catchments water system to aid in assessing the sustainability of policies that address the aforementioned challenges. The water–energy–food (WEF) nexus approach, which encourages system thinking by considering interconnections among water, energy, and food resources when developing integrated natural resource management strategies, was used to perform the evaluation. The water system's reliability in meeting projected domestic, agricultural, and energy water demands under climate change conditions was used for gauging the sustainability of the development plans. Findings projected the existing water policy plans to increase the domestic water provision by >70% under climate change; however, the 20% under climate change, are thus recommended for future water resource management research and dialogue in the Buffalo River catchment. HIGHLIGHTS Water demands and supply reliability under climate change in the Buffalo River catchment, KwaZulu-Natal, South Africa, were analysed throughout the 21st century using the Representative Concentration Pathways 4.5 and 8.5.; Existing policy plans were modelled, and results displayed no improvements in irrigation water provisions.; Adaptation strategies were created which improved the catchment's water supply distribution.;

This paper presents a finite element analysis (FEA) of and reliability study on concrete-filled steel tube (CFST) members under the combined effects of corrosion and compressive loading. First, a stochastic-based FE model is established through the proposed secondary development program based on ABAQUS 2021 software. The model could account for the uncertainties of material, geometric, and corrosion effect on CFST members. The reliability of the built model was validated through experimental data of corroded CFST members under compression loading. Subsequently, the compressive performance of CFST under a combination of corrosion and loading was further investigated by numerical parameter analysis. A total of 1800 models were created to clarify the coupling mechanism among the core concrete strength, the steel tube strength, the steel ratio, and the maximum strength of the CFST member. Three theoretical formulas presented in classical design standards were used to calculate the axial compressive strength of the corroded CFST, and the uncertainty parameters μkp and δkp were also obtained for the discussed design formulas. Finally, the First Order and Second Moment (FOSM) method was employed to estimate the reliability indices β across different standards. The calculations revealed that the reliability indices β according to European standard ranges from 2.93 to 5.52, with some results falling below the target reliability index βT of 3.65. In addition, the multi-parameter coupling effects on reliability index β were investigated, and the main influencing factors were obtained. By leveraging the reliability analysis, reasonable design requirements can be proposed for CFST members under the coupling effects of corrosion and external load, which provides a design basis for the CFST member.

Digital image correlation (DIC), a widely used non-contact measurement technique, often requires empirical tuning of several algorithmic parameters to strike a balance between computational accuracy and efficiency. This paper introduces a novel uncertainty analysis approach aimed at optimizing the parameter intervals of a DIC algorithm. Specifically, the method leverages the inverse compositional Gauss–Newton algorithm combined with a prediction-correction scheme (IC-GN-PC), considering three critical parameters as interval variables. Uncertainty analysis is conducted using a non-probabilistic interval-based multidimensional parallelepiped model, where accuracy and efficiency serve as the reliability indexes. To achieve both high computational accuracy and efficiency, these two reliability indexes are simultaneously improved by optimizing the chosen parameter intervals. The optimized algorithm parameters are subsequently tested and validated through two case studies. The proposed method can be generalized to enhance multiple aspects of an algorithm’s performance by optimizing the relevant parameter intervals.

Fibre-reinforced polymer (FRP) reinforcement has been employed as an alternative to conventional steel reinforcement in concrete structures, which is attributed to its excellent strength and corrosion resistance. However, one drawback is that FRP reinforcements are brittle and affect the ductility of concrete structures. One of the recent effective techniques proposed to overcome ductility issues is the compression yielding (CY) concept. The CY mechanism allows the structure to fail differently than the conventional FRP-reinforced concrete structure. Thus, the existing design recommendations as per the current codes for FRP-reinforced concrete structures are not appropriate. Hence, reliability studies are crucial for the development of a functional CY beam design in order to emphasise the structure’s lifetime performance and to guarantee safety requirements. In this study, a reliability-based design approach is developed for a compression-yielded FRP-reinforced concrete beam (CY beam) using load and resistance factor design (LRFD). Firstly, the flexural failure modes of CY beams are discussed. The uncertainties involved in the development of the probabilistic model for the CY beam are defined. A case study is consequently conducted for a CY beam with random variables that are associated with the statistical characteristics of material properties and load. The reliability analysis method employed in this research is the Hasofer–Lind method. The results suggest the importance of choosing appropriate design variables and stochastic parameters for CY blocks that contribute to a higher level of reliability. The reliability index and resistance factors of a CY beam are then evaluated using the Monte Carlo Simulation computational method. The reliability index value of 3.336 is obtained from the simulation, which indicates that the CY beam demonstrates ductile behaviour. The results not only demonstrate ductile behaviour but also contribute to a possible reduction in material costs and a substantial safety margin. When compared to conventional FRP-reinforced concrete beams, for different load ratios, CY beams showed higher resistance and better reliability levels.

Fatigue crack propagation tests are carried out on arc-shaped specimens prepared from MDPE gas pipes. Damage zone characterization is achieved using the diamond wafer sectioning technique from partially propagated and prematurely arrested cracks. Damage ahead of the crack-tip is used to assess a damage parameter and reliability based on statistical laws and subsequent use the PHIMECA Software. It is shown that a length and a width associated with a corresponding change in thickness at the fracture surface satisfactorily describe the damage zone size. The 3-parameter Weibull model gives the best reliability behavior and a critical lifetime of 82%. When considering separately both the Dugdale model and experimental damage zone measurements, it is possible to establish the evolution of the reliability index as a function of crack length. It is concluded that the reliability index approach based on damage provides a more consistent representation compared to analytical models.

Recent years have seen a significant increase in structural engineers' interest in the assessment of reliability and structural safety. The Reliability-Based Design Optimization (RBDO) method has been utilized to create the most efficient and safe design of structures. Although there have been several theoretical advances in reliability analysis, computational barriers still occur in realistic problems. The purpose of this paper is to provide a process for the optimization of dome truss structures based on reliability. For this purpose, a flowchart including the process of Deterministic Design Optimization (DDO) and RBDO was presented. An evaluation of the reliability of the structure is made by using random variables to represent uncertain parameters. Throughout this study, random variables such as the module of elasticity, material density, and the cross-sectional area of the elements are considered. The deterministic constraints for DDO are the vertical displacement of free nodes and the demand-capacity ratio of all members. Also, reliability index 3 is set as the minimum target reliability index. Meta-heuristic algorithms can be used to achieve optimal design and appropriate safety since mathematical calculations are time-consuming. As part of this study, the Enhanced Vibration Particle System (EVPS) and Vibration Particle System (VPS) have been applied to DDO (incorporating reliability assessment) and RBDO of three dome trusses. The results were obtained using the processes of RBDO and DDO without any deviation in the acceptable space. The solution of RBDO will increase the weight and safety of structures.

Long-span cable-supported bridges constitute the most common type of bridge with a span of more than 400 m. They are generally designed as a double-tower long-span structure with good spanning capacity and economic performance. Wind resistance safety performance is the main index used to control the long-span cable-supported bridge structure. During the life of a long-span cable-supported bridge structure, because the service life of the cables is far shorter than the design life of the structure, the wind resistance performance of the structure will inevitably deteriorate significantly, which will seriously affect the structural service performance of symmetric cable-supported bridges. Under strong wind loads, the static wind stability and flutter stability of cable-stayed bridge structures are components of the limit state of bearing capacity, which directly affects the safety performance of the structure. We take the flutter and static wind stability of a long-span cable-supported bridge structure as the main design control index, use inverse reliability theory to calculate the reliability index of a symmetric cable-supported bridge structure, use inverse reliability theory to calculate the safety factor of a symmetric cable-supported bridge structure, and evaluate the time-varying wind resistance performance of a long-span cable-supported bridge structure by comprehensively considering the reliability index and safety factor. Taking a practical project concerning a long-span cable-supported bridge as a specific case, the time-varying wind resistance reliability of the bridge throughout its operation for more than 30 years is analyzed along with the parameter sensitivity. The results show that the wind resistance performance of the cable-supported bridge structure is obviously affected by its cables, and the degradation of cable performance will have a significant impact on the time-varying wind resistance performance of the structure, especially the critical wind speed of the structure, which has obvious time-varying characteristics. The safety factor and reliability index can be used to objectively evaluate the time-varying wind resistance performance of long-span cable-supported bridge structures. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Southeast University / Dongnan Daxue Xuebao is the property of Journal of Southeast University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Shanghai Jiao Tong University (1006-2467) is the property of Journal of Shanghai Jiao Tong University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper employs probability methods to evaluate the fire safety performance of prestressed steel–concrete beam bridges based on simulation experimental research. Firstly, fire simulation experimental sample analysis was conducted on actual small box girder bridges to assess the structural response of prestressed steel–concrete structures to fire, as is in line with engineering practice. Next, we constructed a reliability analysis model to investigate the fire resistance performance of prestressed steel–concrete beam bridges. Combining reliability theory with the finite element method, we established a reliability analysis method for the fire resistance performance of prestressed steel–concrete beam bridges. Subsequently, we proposed a safety factor evaluation model for the fire resistance performance of prestressed steel–concrete beam bridges and then established a safety factor evaluation method for the fire resistance performance of prestressed steel–concrete beam bridges based on reliability back analysis. Finally, based on the analysis of the post-fire structural response in the specific case of a steel–concrete continuous beam bridge project moving from conditions of being simply supported to continuously prestressed, a structural resistance sample of the prestressed steel–concrete beam bridge was generated via the uniform design method, and statistical analysis was conducted. Subsequently, probability methods were used to evaluate the safety of the prestressed steel–concrete beam bridge after a fire. Through analysis, we concluded that the duration of the fire had a significant impact on the structural performance of prestressed steel–concrete beam bridges and that the randomness of parameters had a significant impact on the safety reserve of prestressed steel–concrete beam bridges following the fire. Going forward, it is necessary to pay attention to this factor in specific engineering practices and strengthen the monitoring and statistical analysis of structural random characteristics. [ABSTRACT FROM AUTHOR]