This study investigates the crashworthiness of corrugated beam guardrails through nonlinear dynamic simulations. A novel design incorporating double anti-blocking blocks is proposed and evaluated. The analysis reveals that while conventional guardrails satisfy basic buffering requirements, they exhibit problematic wheel-column blocking phenomena. Key findings demonstrate that vehicle kinetic energy is predominantly transformed into deformation energy, with reduced energy variation facilitating safer vehicle redirection. Critical thresholds are identified at impact velocities exceeding 120 km/h or collision angles >= 25 degrees, where blocking effects intensify significantly, often preventing successful vehicle redirection and causing substantial front-end deformation. Parametric studies establish an inverse relationship between structural thickness (both columns and plates) and energy absorption capacity. The research determines optimal material specifications: columns perform best at 4.5 mm wall thickness (with 5.0 mm as the upper limit), while guardrail plates should maintain a minimum 3.0 mm thickness. The innovative double-block design demonstrates remarkable improvements, achieving a 30.7 % reduction in peak collision forces while completely eliminating blocking issues. Energy distribution analysis shows the new configuration reduces the vehicle's share of total deformation energy from 75.7 % to 68.7 %, indicating enhanced energy absorption by the guardrail system itself. These findings provide valuable engineering guidelines for optimizing highway safety barrier performance under various impact scenarios.

This paper presents a fatigue reliability analysis frame of ductile iron (DI) pipes using the probability density evolution method (PDEM). The proposed frame performs the fatigue reliability assessment of DI pipes based on experimental data. First, a fatigue failure principle of DI pipes is established based on the failure analysis of socket joints. Subsequently, Miner's linear cumulative damage theory is adopted to establish the fatigue life model of DI pipes under traffic loads. A fatigue limit state function for DI pipes is then formulated, in which the maximum joint rotation angle is adopted as the assessment parameter. Finally, by employing the PDEM, the fatigue reliability of DN200 DI pipes is evaluated as a case study. And the fatigue reliability under different leakage states is obtained where the parameters are determined by the fatigue tests on two DN200 DI pipes. The results indicate that the fatigue life of the pipe buried at 0.5m is less than the design service life of 50 years. Moreover, the proposed method is validated through a field investigation of leakage incidents in water supply pipes across several districts of Shanghai.

As one of critical urban infrastructures, the basic function of water distribution networks (WDNs) is to provide essential water for residential and industrial use. Accurate assessment of pipe roughness coefficient is crucial for analyzing the functional performance of WDNs under operation and disasters, such as earthquakes. Existing assessment methods for pipe roughness coefficient face challenges including: (1) physically, governing laws are not fully understood; (2) data-wise, lacking direct pipe roughness data, and head/flow monitoring does not cover all nodes. Therefore, relying solely on physical or data-driven methods is insufficient to assess pipe roughness coefficient. To this end, this paper proposes a novel method to assess pipe roughness coefficient based on physics-data fusion. Specifically, this method is achieved by embedding physical constraint mechanisms into data expression models. This approach leverages the strengths of both physical and data methods, effectively overcoming issues of insufficient monitoring data and underdetermined problems in assessment of pipe roughness coefficient. It enables accurate and efficient assessment even when only total water consumption is known, without requiring individual nodal consumption. The proposed method is applied to a small-scale WDN and a real-world WDN for case study. The results show that the proposed method can achieve accurate and efficient assessment of pipe roughness coefficient of the case WDNs.

The hybrid connection, which integrates satisfactory performance of the wet connection and high assembly efficiency of the dry connection, is deemed promising in the precast concrete (PC) frame structures. In this paper, a novel PC frame column-column joint with a hoop plate (HP) for the connection of longitudinal reinforcement is proposed and investigated comprehensively. This connection method overcomes the operation difficulties and grouting defect of the grouted sleeve. To study the performance of the novel column-column joint, pilot tensile tests and main cyclic loading tests were both conducted on the column joint specimens. The design method of the HP was deduced to ensure the reliable connection of the HP. Results indicated that all specimens exhibited a similar flexural failure mode, accompanied by concrete crushing at the column bottom. Compared with the castin-place (CIP) column, the PC column showed a 0.3 % higher bearing capacity but a 5.0 % lower ductility. The PC column could satisfy the criterion of "equivalent to CIP" when the HP thickness exceeded 20 mm. Finally, refined finite element models of the novel PC columns were established, and the influence of the HP thickness on the performance of the PC column was investigated in detail. Experimental and numerical results showed great consistency. When the HP thickness was lower than the theoretical critical value, the performance of the novel PC column was augmented greatly as the HP thickness increased. Excessively increasing the HP thickness did not enhance its performance remarkably.

Studying the local stability of steel arches is a key issue in design, particularly considering non-linear effects. However, existing research still has shortcomings, and the analysis cost when considering non-linear factors has significantly increased. Multi-scale models can provide ideas to address these issues. First, a beam element model and a beam–shell element multi-scale model were established for a single-arch ribbed steel box tied arch; based on elastic stability analysis, non-linear factors were considered in order to study its overall and local stability, as well as the sensitivity of structural parameters to local stability. The results show that the multi-scale model’s live load ratio coefficients were 13.43% and 13.09% lower than those of the beam element model in two different loading scenarios. This indicates that ignoring local instability can overestimate stability. Sensitivity analysis shows that the number of diaphragms seriously affects stability. For 1–3 diaphragms, the coefficient increases with number. Longitudinal stiffener thickness from 12 mm to 18 mm raised the coefficient and reduced the top plate’s transverse wave buckling tendency. When the number of longitudinal stiffeners (per side) on the top plate is 2–5, the coefficient increased with number. Changing stiffener type from rigid to flexible shifted the plastic zone location from the top plate and its stiffeners to the web plate and its stiffeners.

Buried steel pipes are extensively utilized in urban water supply and gas supply systems owing to their superior mechanical properties and cost-effectiveness. However, these pipes are vulnerable to corrosion under complex environmental conditions, leading to a reduction in cross-sectional area. Moreover, when subjected to cyclic traffic loads, this degradation significantly increases the susceptibility to fatigue failure. This study investigates the fatigue performance of corroded DN200 steel pipes through full-scale bending fatigue experiments. Accelerated corrosion treatment was first conducted on three specimens to simulate the corroded pipes. Subsequently, fatigue tests were performed on one uncorroded pipe and three corroded pipes with different corrosion durations. The response of the pipes under traffic loads—derived from statistical traffic data, soil pressure, and self-weight—was simulated using ABAQUS to determine the fatigue loading amplitudes. The relationship between loading amplitude and fatigue life was established based on experimental data. Results indicate a progressive decrease in corrosion fatigue life with increasing corrosion rate. Finally, finite element simulations incorporating a combined uniform and pitting corrosion model, executed in ABAQUS and FE-SAFE, showed strong agreement with experimental results. Moreover, a fatigue life evaluation for corroded steel pipes is proposed, demonstrating good predictive accuracy.

Regular prefabricated frame configuration that locates the connection region at the joints can draw problems of reinforcement bar congestion and low joint strength. To address these issues, transferring the connection away from the joint is deemed an alternative. In this paper, a novel mid-span column connection method using mechanical threaded sleeves for prefabricated concrete (PC) columns is proposed. Three 1/2-scaled PC column specimens were produced and subjected to cyclic loading tests. Investigation parameters for the test included the axial load ratio and the loading scheme, to evaluate the seismic performance at different working conditions. The structural performances of failure modes, strength, deformation capacity, stiffness, ductility, and energy dissipation of the specimens were carefully discussed. The results showed that the specimens all performed well and were competent at different loading conditions.

Water distribution networks (WDNs) have suffered severe damages under earthquakes. Therefore, it is of great significance to analyze the seismic reliability of WDNs. However, to our best knowledge, few studies have involved the seismic reliability of in-service WDNs. To this end, in this study, a framework for assessing the seismic reliability of in-service WDNs is presented. Firstly, the pipe daily failure probability is predicted accurately via the deep learning algorithm. Secondly, the pipe fragility model based on pipe seismic reliability is improved by coupling with the daily failure probability, which makes the simulation results of the fragility model closer to the actual damage data of pipes under earthquakes. Thirdly, the nodal heads of WDNs are derived through hydraulic analysis of WDNs with leakages. Then, based on Monte-Carlo simulation method, the seismic reliability of WDNs is obtained by counting the number of times the nodal head exceeds the demand head. Finally, the seismic reliability of an actual WDN in China, is assessed in detail as a case study to demonstrate the proposed framework. Results show that nodal seismic reliability can be influenced by service time, pipe roughness, the distance from water plant to the node and the loop configuration.

Earthquakes cause great damage to urban critical infrastructure systems, so it is important to assess and enhance the seismic resilience of urban critical infrastructure. There are two problems in the contemporary assessment of the resilience of critical infrastructure systems: the research on infrastructure systems focuses less on the function, which makes it difficult to restore the physical characteristics of the system. The consideration of the correlation relationship between infrastructure systems is not comprehensive enough. In this paper, a new functional simulation-based approach is proposed to assess the seismic resilience of interdependent urban electric power and gas systems under seismic effects. Function-based simulation modeling of the urban electric power system and gas system is performed, and DC current analysis is used to perform post-earthquake functional analysis of the electric power system and maximum flow algorithm is used to perform post-earthquake functional analysis of the gas system. The correlation relationships and cascading failures within each subsystem of the power and gas systems and between the two infrastructure systems are considered in the modeling. Interdependent links across infrastructure network systems are constructed by considering geographic and functional linkages between system components during the earthquake damage phase as well as the post-disaster restoration phase. Function-based disaster response and resilience assessment of linked infrastructures under seismic effects are realized. A combined restoration strategy between two systems is adopted to determine the restoration sequence of electric components and then match the optimal set of gas components based on the restoration time of each electric component, taking into account the correlation between electric and gas. The results show that the approach considering multiple correlations and based on functional simulation better simulates the fault propagation after a disaster and the dynamics of post-earthquake restoration, and the framework and restoration strategy proposed in this paper are more accurate and instructive for assessing resilience.

Shield tunneling generates a significant amount of shield muck, which is commonly treated as waste and requires long-distance transport and extensive land occupation for disposal. One potential solution is to utilize shield muck to produce synchronous grouting material, which is required in shield tunnel construction. This study explores the use of industry byproducts, namely ground granulated blast-furnace slag (GGBS) and carbide sludge (CS), in the treatment of shield muck to produce synchronous grout, aiming to enhance treatment efficiency and reduce cost. The strength, consistency, flowability, setting time, and microstructure characteristics of GGBS-CS treated shield muck were examined and compared with those of corresponding ordinary Portland cement (OPC) specimens. Results showed that the optimum strength of GGBS-CS-treated shield muck was 0.86 MPa at 3 days and 3.20 MPa at 28 days, which were 2.5 and 3.2 times higher than that of OPC specimens at these two ages, respectively. In addition, other engineering properties, including consistency, flowability, bleeding rate, and setting time of GGBS-CS-treated shield muck met the standard requirements for synchronous grouting. Microscopic analyses identified the presence of calcium-silicate-hydrate (C-S-H) and ettringite in both GGBS-CSand OPC-treated shield muck, which were generated through binder hydration and pozzolanic reactions of shield muck minerals. Cost analysis indicated that this technique could reduce the construction cost by 279 CNY per cubic meter in the production of synchronous grout. The findings of this research support the reutilization of shield muck in practical shield tunnel projects.

This paper proposes a time-domain approach to identify eccentricity in three-dimensional multi-storey structures exhibiting nonaxial stiffness eccentricity. Improved lateral-torsional coupled equations of motion are employed to identify the location of the center of rigidity for each storey, using horizontal acceleration measurements in two orthogonal directions obtained from multiple points across each storey. This study mitigates errors typically associated with Fourier transformation by applying a time-domain approach and redefines the dynamic equations for calculating structural eccentricities, with a detailed formulation of the torsional stiffness matrix. Additionally, a novel objective function, based on the root-mean-square of the residual force in the time-domain equations of motion, is proposed to simultaneously identify bidirectional eccentricities of the structure. A numerical example illustrates the implementation and effectiveness of the proposed method. The feasibility of the method is demonstrated using a traditional Chinese timber benchmark structure. This approach overcomes several limitations in current methods and provides a streamlined solution for eccentricity identification in complex asymmetric structures.

This research proposes a seismic optimization design method for water distribution networks under multiple constraints. Through an analysis of real water distribution networks from the perspective of network science, the regularity of their topological characteristics is revealed. Specifically, the product of average closeness centrality and average distance, the product of global efficiency and average distance, the ratio of average distance to effective diameter, and the distribution of node degrees exhibit specific value patterns. Taking water distribution network’s annual reduced cost as optimization object, along with the seismic reliability and the network’s topological characteristics as constraints, a network topology optimization model is established. Based on automatic generation strategy, genetic algorithms are employed to solve the seismic optimization model. The results indicate the optimized network meets the requirements for seismic performance and exhibits closer resemblance to real networks in terms of topological characteristics.

This work developed a novel hybrid machine learning (ML) framework for pipeline integrity assessment under landslide conditions. The proposed framework initially integrated a 3D nonlinear finite element (FE) model to investigate pipeline failure mechanisms, track failure locations, and generate pipe's maximum von Mises stress (MVMS) datasets. Subsequently, an enhanced Extreme Learning Machine (LSBES-ELM) model, optimized via three metaheuristic algorithms (Bald Eagle Search, Levy flight, and Simulated Annealing), was developed for high-precision MVMS prediction. Finally, Monte Carlo Simulation (MCS) algorithm was coupled with the LSBES-ELM model for pipe's reliability evaluation. Results identified the landslide-opposing side (LOS) as a critical failure-monitoring location. Correlation analysis highlighted landslide displacement (LD) and width (LW) as dominant factors governing pipeline failure. The developed LSBES-ELM model, configured with a 90:10 training-test split and 40 BES populations, demonstrated superior predictive performance (R2 = 0.980, MAE = 10.0899, MRE = 0.0214, MSE = 174.437, RMSE = 13.2075, RE = [0.0029, 0.0591]), and the ability to eliminate outliers, indicating its superiority over BES-ELM and conventional ELM in simulating landslide-induced pipeline response. Furthermore, the LSBES-ELM-MCS model is rigorously validated for its high robustness in different scenarios through 10-fold cross validation, indicating its as a reliable surrogate for probabilistic safety assessment. This study advances ML-based pipeline geohazard assessment and provides actionable solutions for safeguarding pipeline integrity in landslide-prone regions globally.

Composite slabs, which consist of a precast concrete bottom panel and a cast‐ in situ concrete topping, are widely used in modern precast concrete buildings. The conventional precast concrete bottom panels are more prone to damage during transportation and hoisting, which can seriously hinder construction efficiency due to extended lap‐splice rebars. This study introduces a new splicing slab design featuring L‐shaped grooves and lap‐splice rebars to improve construction efficiency. Full‐scale experimental testing was conducted to analyze load–deflection responses, crack patterns, failure modes, and strain distributions. A numerical model was developed to reproduce the testing, while a simplified theoretical model was used for design prediction. The results show that the new splicing slab exhibits ductile failure without interface cracks, demonstrating a three‐stage load–deflection response and effective force transmission through lap‐splice rebars. Finally, the design method of joints is proposed, laying a groundwork for the optimal design of precast concrete slabs with joints.

Most existing studies on the seismic reliability of water distribution networks (WDNs) neglect pipe deterioration over service life, including increased pipe roughness and elevated daily failure rates such as leaks. This neglect of pipe deterioration essentially treats in-service WDNs as new systems, which may lead to overestimated seismic reliability. This study proposes a novel framework that integrates established deterioration models to comprehensively assess the seismic reliability of in-service WDNs. First, the daily pipe failure probability, predicted using a deep learning algorithm, is incorporated into a pipe fragility model based on pipe reliability. A seismic risk assessment model is simultaneously applied to evaluate damage to pumping stations and water plants. Second, nodal heads following seismic events are derived via hydraulic analysis, accounting for multiple component types, including pipes, nodes, pumping stations, and water plants. Pipe roughness is modeled using a time-dependent function that reflects the progressive decline in hydraulic performance. Third, a probability density evolution method is employed to account for uncertainties in the characteristics of pipes, pumping stations, and water plants, enabling the derivation of nodal head distributions and calculation of seismic reliability. Finally, the proposed framework is applied to a real large-scale WDN in China, demonstrating the compounded effects of integrated deterioration mechanisms and highlighting the importance of such considerations for realistic seismic reliability assessment.

Urban water supply pipelines experience repetitive traffic loads during their operational lifespan, potentially leading to fatigue failure. However, existing research focuses primarily on the static or dynamic mechanical responses of pipes, with limited studies on the fatigue performance of pipes. This study investigates the fatigue performance and failure mechanism of DN200 ductile iron (DI) pipes with socket joints under traffic loads and water pressure through bending fatigue tests. First, the mechanical responses of pipe joints under traffic loads derived from statistical data on highway traffic loads, soil pressure, and self-weight are calculated using ABAQUS to give the fatigue test load amplitude. Subsequently, tests are conducted on three DN200 DI pipes under a water pressure of 0.2 MPa: one for a monotonic test and two for fatigue tests under extra car and bus loads, respectively. The fatigue life of pipes under various traffic load combinations is analyzed using cumulative damage theory. Moreover, the relationship between fatigue load amplitude and number of cycles for DN200 DI pipes are obtained on the basis of the test data. Results show that the maximum rotation angle of joint is an important indicator of failure. Finally, a theoretical method for calculating the joint angle is proposed on the basis of geometric dimensions. A good agreement between the test and theoretical results is observed. Thus, the proposed method can obtain the fatigue performance of joints effectively.