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The seismic fragility of water supply networks is an important research component for lifeline engineering in earthquake-prone regions. An accurate computational model was established to rapidly and efficiently assess pipeline damage under seismic excitation. In this study, the fragility of the pipeline network is deduced based on Copula function technology and the series-parallel model. This solves the low accuracy problem caused by simplifying elbow, tee, and other nodes and ignores the correlation between connected components in the fragility calculation of the buried pipeline network. Then, the shaking table tests of the elbow pipe, tee pipe, and scale pipeline network are performed, and the prototype pipeline network's finite element comparative calculation model is also established. Then, the optimal Copula function for the pipeline network, the Gumbel Copula function, is obtained by calculating the correlation between each component's seismic demand. It was found that the seismic demand of pipe and elbow components in the sand is higher than that in the clay, while the opposite is valid for the tee component. After that, a two-parameter log-normal distribution is employed to obtain the seismic fragility of three types of components in different soil properties. It was also found that the maximum failure probability can be obtained from the elbow leakage. The fragility of the elbow pipe is greater than that of the tee pipe. The fragility of components is then applied to the fragility calculation of the scale pipeline network by a series-parallel model, and the obtained results are compared with numerical simulations. It is demonstrated that the series-parallel combination calculation-based results have a high safety reserve for the pipeline design. At present, urban municipal pipeline networks face many challenges in earthquake-prone regions, such as old pipeline infrastructure and poor seismic performance, which make their nodes and push-on joints vulnerable to damage. Based on the above social needs, this paper focuses on the accurate calculation theory of the seismic fragility of the buried water supply network. A more reasonable calculation method of the reliability of the pipeline network is established by considering the influence of the fragility of connected pipe components. This method employs the failure probability of various components to accurately calculate the fragility of the large and complex pipeline network. This study can provide basic theories for the seismic fragility of pipeline networks, the calculation of seismic connectivity, and the construction of resilient pipeline networks. In addition, the conclusions proposed in the study, such as the fragility comparison of tees and elbows and the design concept of "strong nodes", can guide the design of pipeline network nodes, which has great practical significance and social benefits. [ABSTRACT FROM AUTHOR]

Rockfill strength parameters are important indicators of the stability of a rockfill dam slope. Therefore, a rational representation of the distribution characteristics of these parameters is extremely important to accurately assess the stability of the dynamic response and reliability of the three-dimensional (3D) slope of a rockfill dam. A joint distribution model of the rockfill strength parameters is constructed in this study using the copula function. In addition, a dynamic reliability analysis method for slope stability is proposed using a number-theoretical method and the generalized probability density evolution method (GPDEM). First, the method is validated by comparing the results for a numerical example with those obtained by Monte Carlo simulation (MCS). Second, the traditional and proposed joint distribution models are comparatively analyzed in terms of the dynamic response and reliability. Finally, the effect of the type of copula function on the dynamic reliability of the slope is investigated. The results show that the copula theory, the number-theoretical method, and the GPDEM provide an effective approach to analyze the dynamic response and reliability of slope stability. The randomness of rockfill strength parameters is sensitive to the safety factor of the slope stability of rockfill dams. The reliability analysis method can reasonably characterize the influence of strength parameter uncertainty on dam slope stability, which makes up for the deficiency of using a single safety measurement standard in the deterministic analysis method. The copula function can reasonably characterize the nonnormal distribution characteristics of rockfill strength parameters, improve the calculation accuracy of the slope stability reliability of rockfill dams, and provide an important scientific basis for the accurate safety assessment of dam slope stability. The type of copula function has an important impact on the dynamic reliability results for slope stability. Thus, it is extremely important to build a joint distribution model of rockfill strength parameters based on a rational selection of the optimal copula function. [ABSTRACT FROM AUTHOR]

The reliability of concrete in complex environments is the basis for improving the reliability of concrete structures. A concrete reliability assessment based on multiple degradation factor is proposed. First, chloride penetration and fatigue damage are selected as two degradation parameters for concrete, and series tests are developed to investigate the surface chloride concentration, diffusion coefficient, and degradation of residual strength under coupled effect of chloride penetration and fatigue. Then, two marginal distribution functions of the durability reliability of the concrete are deduced based on two failure modes. Subsequently, fatigue loading the parameters of different typical copula functions are obtained by using the maximum likelihood method (MLM), and copula function selection is carried out according to the Akaike information criterion (AIC) criterion. The joint distribution function is then derived by fusing the two marginal distribution functions using the selected copula function, and a remaining durability reliability model is obtained. Finally, the proposed model is verified by experimental data. This method should be considered as a reference for the evaluation and reliability calculation of concrete structures. [ABSTRACT FROM AUTHOR]

The prediction of the extreme value of the wind pressure receives significant attention from the wind engineering community. However, the correlation among extreme wind pressures associated with different locations on the building surface is less addressed. In this study, the characterization of the dependence structure of extreme wind pressures and its application to roofing damage estimation are presented. First, three methods to model the dependence structure of extreme wind pressures, including multivariate extreme value theory, copula function, and Nataf transformation, are reviewed. Then, the asymptotic property of the bivariate non-Gaussian random vector will be established and the partial correlation for the data within finite duration is discussed. Furthermore, the dependence structure and asymptotical properties of extreme wind pressure coefficients are investigated based on the very long wind tunnel data. The correlation of extreme pressures considering the randomness of the annual maximum mean wind speed is also addressed. Finally, the application of the correlation of extreme wind pressures on the damage estimation for the asphalt shingle roofing is discussed. [ABSTRACT FROM AUTHOR]