Search Results (1,723)

We propose a novel hybrid architecture that integrates a continuous-time Liquid Neural Network with an optimized Long Short-Term Memory network for seismic vulnerability state assessment of ancient halls. The proposed system processes multi-source structural monitoring data, including acceleration, strain, displacement, temperature, and humidity signals. A central challenge in this domain is the long-term state drift that occurs when continuous-time models are exposed to prolonged seismic events or sequences of aftershocks. To address this issue, we introduce a learnable event-triggered discrete reset mechanism that monitors a prediction error signal and an auxiliary drift accumulation variable. When a trigger condition is met, the Liquid Neural Network hidden state is reinitialized to a learned baseline state, thereby preventing divergence from physically plausible structural dynamics. This reset mechanism is inspired by hybrid small-gain and impulsive control frameworks and provides rigorous stability guarantees. The continuous-time dynamics are modeled as a neural ordinary differential equation with a sinusoidal activation function, solved via a fixed-step Runge–Kutta integrator. The discrete-time pathway employs a two-layer LSTM with Bayesian-optimized hyperparameters. A learned attention mechanism fuses the hidden states from both pathways, and the combined representation is passed through a feedforward network to produce a four-class seismic vulnerability index. The entire system is trained end-to-end with an adaptive loss function that balances reconstruction accuracy, drift penalization, and classification performance. We first pre-train the model on synthetic data generated from a calibrated finite element model of a representative ancient hall in Rucheng, Hunan. Transfer learning then fine-tunes the model on real monitoring data. Our approach replaces conventional fragility-curve-based estimates with a data-driven, adaptive vulnerability assessment that is site-specific and robust to non-stationary excitation. The hybrid switched-system framework therefore offers a principled solution to the state drift problem while maintaining the expressive power of continuous-time neural dynamics. Full article

A methodological framework for real estate collateral under CRR3, taking into account the International Valuation Standards (IVS) and relevant ESG factors, including physical and environmental risks, in determining prudential value. The study includes illustrative numerical applications to property resilience and physical risks. This paper examines the methodological implications of property value (PV) under Article 229 of Regulation (EU) 2024/1623, which, in implementation of the Basel III framework, amended Regulation (EU) No 575/2013 on prudential requirements for credit institutions and investment firms, for real estate collateral valuation (CRR3). It considers how current market value (MV) may be tested against the value sustainable over the life of the loan, with particular attention to property resilience, energy efficiency and materially relevant environmental and physical risks. The study combines the CRR3 framework, European Banking Autority (EBA) Guidelines and European Central Bank (ECB) Good Practices with valuation standards and a targeted critical review of recent literature. Drawing on the IVS and the Italian property valuation standard, it proposes a market-capped and sustainability-tested framework for determining property value, in which risk-adjusted market value (MVRA) is used as an analytical variable to identify residual risk not already reflected in market prices. The A_phys formulation provides a first-order analytical representation of event-based physical and environmental risk adjustments through probability, uninsured property damage, property-level loss of use, non-overlapping restoration costs, discounting, and a residual-risk coefficient intended to control double counting. The framework is then applied to three hypothetical numerical worked cases in different Italian Regions: a residential property exposed to hydraulic risk in Emilia-Romagna, an income-producing commercial property exposed to seismic risk in the Marche, and a residential property with partial seismic improvement in Sicily (Messina). The cases include structured comparable analysis, illustrative scenario parameterization, and multivariate sensitivity analysis. They illustrate the computational mechanics and internal consistency of the proposed framework but do not constitute empirical calibration, validation, or evidence of real-world predictive performance; the residual-risk parameters still require calibration using observed market, hazard, vulnerability, insurance, and loss data. The framework may affect the exposure-to-value ratio (ETV) and, depending on the applicable prudential treatment, risk-weighted exposure amounts. The broader ESG perimeter recognized by valuation standards is also acknowledged: Social and Governance variables are not numerically parameterized in the three worked cases, but, where material, they should be mapped to transparent and non-duplicative valuation channels. Full article

In view of the seismic performance deficiencies commonly observed in existing reinforced concrete (RC) frame structures, the application of fiber-reinforced polymer (FRP) composites for seismic strengthening has become a key technical approach to enhance the safety reserve of such structures. However, most existing studies primarily focus on the overall effectiveness of strengthening schemes, while systematic investigations on key geometric parameters, such as strengthening location and length, remain insufficient. In this paper, based on the ABAQUS finite element software and calibrated against a quasi-static test of a 1/2-scale two-story two-bay RC plane frame, refined numerical models of both unstrengthened and FRP-strengthened frames were established. Adopting a “control-variable parametric analysis” strategy and using cross-sectional dimensions as the reference, nine strengthening cases were designed with column-end FRP lengths of 0.5b, 1.5b, and 2.5b and beam-end FRP lengths of 1h, 2h, and 3h. The differential effects of FRP-strengthening lengths at beam and column ends on the seismic performance of the frame structure were revealed. The results indicate that FRP strengthening can effectively enhance the load-bearing capacity and improve the hysteretic performance of members. Nevertheless, the underlying mechanisms by which beam-end and column-end strengthening lengths affect mechanical behavior are fundamentally different: column-end FRP strengthening primarily governs the initial stiffness and load-bearing capacity, with a maximum increase in peak load of 40.7%; beam-end FRP strengthening mainly controls the post-yield stiffness degradation rate and energy dissipation capacity, achieving a peak load increase of up to 53.2%, although the marginal benefit tends to diminish with increasing length. Beam-end strengthening is the critical factor governing the transition of failure mode (from brittle joint shear failure to ductile beam-end flexural failure), while column-end strengthening plays a supplementary role in restraining the formation of column hinges and maintaining the desirable “strong column-weak beam” failure hierarchy. This study reveals the influence of FRP strengthening length on the seismic performance of structures, and to some extent addresses the deficiency of existing studies in systematic parametric analysis. Full article

To investigate the effects of end-plate thickness on the seismic performance and damage evolution of K-shaped eccentrically braced frames with end-plate connections (EPEBFs), two scaled specimens with different end-plate thicknesses were tested under low-cycle reversed loading. The influence of end-plate thickness on mechanical behavior and seismic response was evaluated from failure modes, hysteretic response, skeleton curves, ductility, energy dissipation, and stiffness degradation, together with damage assessment using different models. Refined finite element models were then established for parametric analysis. The results show that EPEBFs exhibit a well-defined plastic development path. Damage in the reference specimen was mainly concentrated in the link and its end-plate connection region, thereby protecting the frame columns, beams, and braces. For the two thicknesses tested, the specimen with thicker end plates showed higher lateral resistance, greater ultimate deformation capacity, and better late-stage resistance retention, but lower displacement ductility, indicating enhanced absolute deformation capacity but reduced post-yield deformation reserve. Thicker end plates also altered stress transfer and plastic development in the connection regions, causing damage to extend toward the frame-beam ends. Among the damage models considered, the elastic–plastic energy dissipation ratio model better captured the accumulation of energy dissipation and plastic deformation. The finite element results agreed well with the tests. Within the investigated range, increasing end-plate thickness mainly improved ultimate deformation capacity and late-stage resistance retention, without a clear monotonic effect on lateral resistance. The findings provide a basis for prefabricated design, damage control, and post-earthquake replacement and repair of EPEBFs. Full article

The mechanisms of frequency dispersion and attenuation of seismic waves in fluid-saturated coal are not yet fully understood, and traditional integer-order viscoelastic models using a single relaxation time struggle to accurately characterize the dynamic response across different frequencies. A new three-component physical fractal viscoelastic model, based on the self-similar fractal pore-fracture structure of saturated coal, decouples matrix and fluid dissipation through two independent Caputo fractional orders (α corresponding to the skeleton and β corresponding to the fluid), distinguishing it from the single-relaxation-time form of standard integer-order elements. Effective stress simultaneously modifies both the fractal orders (α, β) and the relaxation times (τ₂, τ₃), thereby increasing P-wave velocity and reducing the attenuation amplitude and its frequency dependence. In contrast, temperature and gas adsorption change only the relaxation time scale, leading to synchronous changes in wave velocity and attenuation in unison. The model provides petrophysical support for field-scale seismic dispersion inversion, fracture prediction, fluid identification, and sweet spot evaluation in coalbed methane reservoirs. Full article

On 6 February 2023, a sequence of earthquakes in Kahramanmaraş affected eleven cities in southeastern Türkiye. Following the main earthquakes, which caused severe destruction, numerous aftershocks occurred, further amplifying the damage in the region. In this paper, the seismic damage to 51 mosques and their minarets located in Kahramanmaraş city and its districts are structurally evaluated. Based on the field observations, the qualitative damage and performance levels of the structures were determined. Seismic parameters of Kahramanmaraş and its districts, the epicenters of the two earthquakes, were compared. The results show that mosques and minarets with masonry and reinforced concrete structural systems suffered severe damage and collapse. The observed failure modes in the mosques and minarets were analyzed within a cause-and-effect framework. Damage criteria for mosques and minarets have been adapted and assigned to standardized performance levels specified in the Earthquake Risk Management Guide for Historical Buildings by the General Directorate of Foundations in Türkiye: of the mosque complexes examined, 13 reached a level of Collapse; 27 were at the Collapse Prevention level; 3 were classified as having Controlled Damage; 5 as having Limited Damage; and 3 remained undamaged. In addition to the specific structural weaknesses and low mechanical properties of masonry and reinforced concrete building systems, the lack of engineering consultancy during construction and non-compliance with seismic design regulations are also among the causes of failures. Finally, repair and retrofitting solutions for masonry and RC mosques and minarets are proposed. While numerous post-earthquake surveys have primarily examined individual case studies, the novelty of this study lies in the systematic assessment of failure mechanisms in religious buildings located in Kahramanmaraş, the epicenter of the 6th of February 2023 earthquakes, considering both masonry and reinforced concrete systems. Full article

The Cambrian platform-margin shoals in the Yudu area, Tarim Basin, are important targets for deep and ultra-deep hydrocarbon exploration, but their development and reservoir-forming mechanisms remain poorly constrained. This study integrates 3D seismic interpretation, drilling and logging data, core observations, thin-section petrography, and reservoir characterization to investigate shoal architecture, reservoir characteristics, and controlling processes. Seismic data reveal that multistage, basinward-prograding carbonate buildups developed along fault-controlled platform-margin slope breaks adjacent to the Yudu rift trough. Core and petrographic observations show that the shoals are dominated by granular, microbial, algal, and oolitic dolomites, with intercrystalline, dissolution, vuggy, and fracture-related pore systems. High-quality reservoirs are preferentially developed within thick, vertically stacked shoal complexes and are characterized by strong heterogeneity and locally enhanced porosity and permeability. Early dolomitization favored the preservation of primary pore frameworks, whereas subsequent faulting and multistage dissolution generated and enhanced fracture–vuggy reservoir space. The spatial association between platform-margin shoals and the Yudu rift trough further provided favorable conditions for near-source hydrocarbon accumulation. These results demonstrate that Cambrian reservoir development was governed by coupled tectono-sedimentary and diagenetic processes and highlight fault-controlled platform margins as favorable targets for deep and ultra-deep carbonate exploration. Full article

The effects of steel supports on the dynamic characteristics and seismic demands of large three-phase power transformers remain insufficiently quantified. A three-dimensional finite-element model of a 500 kV three-phase transformer was developed to compare configurations without steel support (NS) and with steel support (WS). Modal characteristics and seismic bushing responses were evaluated under seven three-component ground motions. Frequency-response characteristics and global tank rotations were then analyzed, and a double friction pendulum (DFP) base-isolation retrofit was assessed. The lowest natural frequency of the WS model was 1.47 Hz, lower than the 1.84 Hz obtained for the NS model. For the representative X-direction response of high-voltage bushing A, the dominant low-frequency peak of the frequency-response function shifted from approximately 1.89 to 1.64 Hz, while its magnitude increased from approximately 8 to 19. The mean peak maximum principal tensile stress at the root of bushing A increased by 83.1%. The WS model also exhibited greater tank rocking and torsional responses, whose peaks were positively associated with the peak root stresses of bushings A and B. For representative high-voltage bushing B, the DFP retrofit achieved a mean isolation efficiency of approximately 60%. These results elucidate the mechanisms by which steel supports amplify the seismic response of the large 500 kV three-phase power transformer and provide a numerical evaluation of the effectiveness of a DFP base-isolation retrofit for this transformer. Full article

This paper proposes a comprehensive structural design methodology for spatial frameless glass structures, in which toughened glass panels serve as the primary load-bearing elements and provide sufficient resistance to various design loads, including seismic and wind actions. The authors introduce structural systems with innovative configuration patterns to facilitate practical construction. To develop an Allowable Stress Design (ASD) approach for frameless glass structures, this study summarises experimental results and theoretical formulations for determining the allowable stresses of toughened glass panels subjected to in-plane compression and in-plane bending. Furthermore, the allowable load-carrying capacities of bolted joints and the spring constants required for mechanical analysis models are derived. Finally, a practical design procedure is presented, in which glass panels are modelled as equivalent beams and seismic loads are evaluated to verify structural safety. Full article

We propose a resolution-adaptive Bayesian wavelet-denoising method for noisy one-dimensional signals. The main contribution is a spike-and-slab prior whose continuous slab is a mixture of a compactly supported Wendland-type polynomial kernel and the semicircle density, with data-adaptive, resolution-specific mixture weights, produced by a low-dimensional empirical-Bayes trend. The Wendland component concentrates mass near zero and vanishes smoothly at the support boundary, whereas the semicircle component is more dispersed. This construction combines explicit sparsity and support control with an interpretable mechanism for adapting the shrinkage shape across resolutions. Under squared-error loss, we derive the posterior-mean estimator; establish key symmetry, boundedness, continuity, and limiting properties; define pointwise fixed-hyperparameter bias, variance, and risk; and develop an empirical-Bayes estimation procedure. The Wendland contribution has finite-sum expressions under a Laplace working likelihood, while the semicircle contribution is evaluated by stable one-dimensional integration. Simulations using the Bumps, Blocks, Doppler, and HeaviSine signals compare the proposed Gaussian- and Laplace-likelihood versions with universal thresholding, false-discovery-rate (FDR) thresholding, cross-validation (CV), Stein’s unbiased risk estimate (SURE), the Bayesian adaptive multiresolution shrinker (BAMS), and a nonlocal-prior (NLP)-based method. In the primary Gaussian-error simulation study, the Gaussian-likelihood version was the strongest non-NLP method in 24 of the 36 design cells, including 11 of the 12 low signal-to-noise ratio (SNR) cells, and had a substantially more favorable computational profile than the Laplace-likelihood version. Analysis of a seismic acceleration trace from the 2008 Chino Hills earthquake illustrates attenuation of rapid fluctuations and preservation of the dominant acceleration event under the chosen diagnostics. Using the processed channel-1 trace as surrogate truth, the corresponding semi-synthetic validation showed that WS–Gaussian improved on the noisy observation at lower and moderate SNRs but not at the highest SNR. Full article

Two earthquakes greater than Mw 5.5 occurred in Dingri County, Tibet, between 2020 and 2025. Whether a triggering relationship exists between them remains debated. Therefore, in this study, we examine the kinematic mechanisms of the two events and seismogenic faults, as well as the post-seismic Coulomb stress changes. The results show that the maximum slip of the 2020 Dingri earthquake is 1.3 m at a depth of about 3.55 km, with a seismic moment of 6.53 × 10¹⁷ N·m, equivalent to an Mw = 5.8 earthquake. Regarding the 2025 earthquake, the maximum slip of F1 fault is 5.1 m at a depth of about 4.5 km, and the peak slip of the F2 fault is 0.46 m at a depth of about 2.5 km. With a seismic moment of 2.82 × 10¹⁹ N·m, the 2025 earthquake matches an Mw = 6.9 earthquake. The Dengmecuo fault exhibits a deformation rate of about 14.4 mm/yr, and the southern section of the fault is nearly locked before the 2025 earthquake, with a slip deficit of about 13.5 mm/yr. The Coulomb stress change five years after the 2020 earthquake is 10,700 Pa, which exceeds the threshold for triggering subsequent seismic activity, indicating a triggering relationship between the two earthquakes. Full article

Seismic pier-top pounding in high-speed railway bridges transfers short-duration girder-restraint contact forces into bridge piers, coupling local contact damage with global vibration and possible base yielding. This critical review evaluates how evidence and modelling strategies can be transferred from local contact mechanics to pier response and, ultimately, to whole-bridge seismic demand. The literature is synthesized across experimental and refined numerical characterization, reduced-order contact–structure modelling, response-equivalent-pulse construction, and nonlinear whole-bridge analysis. A qualitative evidence-confidence grading is introduced to distinguish the strength and transferability of the available evidence based on study independence, evidence type, and configuration similarity. The primary scope is high-speed railway bridges, while the underlying contact–structure modelling principles are transferable to conventional railway and highway bridges with comparable pier-top restraints, subject to bridge-specific calibration. Conventional spring-dashpot models are computationally efficient but sensitive to contact stiffness, damping, restitution, and damage assumptions, whereas refined finite-element models resolve local response at substantially greater computational cost. Static, impulse-equivalent, and prescribed pulse representations can reduce analysis effort, but agreement in force or impulse alone does not ensure equivalence in pier displacement, base moment, plastic rotation, or residual demand. Demand-oriented pulses can reproduce selected component-level responses within a calibrated applicability domain, while response-triggered loading remains a conditional system-level reduction requiring reliable event logic, state updating, and independent benchmark validation. Future research should prioritize realistic restraint tests, identifiable parameter ranges, multi-demand validation, uncertainty quantification and damage-updatable repeated-impact models. These advances can provide a mechanics-based basis for performance-oriented restraint assessment, while practical design application requires consistency with code-based seismic restraint provisions and post-earthquake track-system serviceability criteria. Full article

Precast concrete frame joints in coastal atmospheric environments are susceptible to mechanical performance degradation caused by chloride-induced corrosion, yet joint-scale numerical studies incorporating multi-indicator time-dependent mechanical responses remain limited. This paper presents a coupled framework that integrates chloride diffusion, corrosion, and finite-element analysis for a typical precast beam–column joint to evaluate the relative changes in seismic performance indicators across service ages of 0, 15, 30, 40, and 50 years. The numerical model was baseline-validated against uncorroded and corroded test specimens under cyclic loading. Time-dependent models accounting for chloride diffusion, rebar corrosion, and material strength degradation were implemented. The elastic modulus reduction was restricted to the damaged covering concrete rather than the intact internal concrete. The simulation results show that mechanical degradation is limited in the early service stage, whereas hysteretic pinching and deformation-related deterioration become more pronounced with increasing service age. By 50 a, the peak load-bearing capacity has decreased by 13.68%, whereas the ultimate displacement and ductility coefficients have declined by 15.10% and 37.40%, respectively. These results should be interpreted as case-specific predictions under the adopted cover thickness, chloride exposure condition, and material parameters rather than as universal deterioration thresholds. The findings indicate that service-life evaluations of precast joints in coastal atmospheric environments should not rely solely on strength indicators but should also incorporate stiffness, ductility, and energy dissipation capacity. Full article

Traditional brick masonry buildings in China are commonly constructed using fired clay grey bricks bonded with glutinous rice mortar, forming a unique historical masonry system with significant cultural value. During long-term service, these structures are vulnerable to environmental deterioration, material aging, and seismic actions, resulting in cracking, deformation, and degradation of structural integrity and load-carrying capacity. Carbon fiber-reinforced polymer (CFRP) sheets have been increasingly applied for strengthening masonry structures due to their high strength-to-weight ratio, corrosion resistance, and convenient installation. However, most existing studies on Fiber-reinforced polymer (FRP)–masonry interfaces have focused on conventional masonry systems, while the interfacial bond behavior and load-transfer characteristics between CFRP sheets and traditional grey brick masonry bonded with glutinous rice mortar remain insufficiently investigated. This study investigates the interfacial bond behavior of CFRP-strengthened traditional grey brick masonry through combined experimental testing and numerical analysis. First, uniaxial compression tests were conducted to determine the mechanical properties of glutinous rice mortar and fired clay grey bricks. Subsequently, double-shear tests considering different CFRP bond widths, bond lengths, and interface integrity conditions were performed to characterize the failure modes, force–displacement responses, and interfacial load-carrying behavior. The effects of interface geometric and integrity conditions were considered to evaluate the load-transfer characteristics of the strengthened interface. Based on the experimental results, a finite element model considering interface behavior was established and verified through comparison with the experimental results, which was subsequently employed to investigate the influence of bond width on interfacial stress transfer behavior beyond the experimental conditions. The results show that interfacial debonding accompanied by near-surface masonry damage dominates the failure process of CFRP–glutinous rice mortar masonry interfaces. Increasing the CFRP bond width enhances the interfacial load-carrying capacity and initial stiffness, while the ultimate capacity exhibits an approximately linear relationship with bond width within the investigated range. Numerical analyses further demonstrate that increasing bond width expands the effective load-transfer region, redistributes interfacial stresses, and delays stiffness degradation. These findings improve the understanding of interfacial bond behavior and load-transfer characteristics in CFRP-strengthened traditional masonry systems and provide references for the design and performance evaluation of strengthening applications in historic masonry structures. Full article

Existing comparative studies on metallic mild steel dampers (SDs) and fluid viscous dampers (FVDs) are primarily limited by the coupling of device type with layout variations, the lack of a unified performance metric, and the absence of multi-level evidence under fixed structural configurations. This study overcomes these limitations by comparing SDs and FVDs under strictly identical conditions—same RC frame, same 26 damper locations, same ground motions, and a unified code-specified drift target—across frequent, design-basis, and rare earthquake levels, supplemented by energy dissipation and added damping ratio analyses. Under frequent earthquakes (FEs), the FVD achieves a maximum story-shear reduction of 33% and effectively controls inter-story drift through its velocity-dependent energy-dissipation mechanism. Under rare earthquakes (REs), the SD demonstrates superior performance, providing a 35% maximum story-shear reduction, while maintaining inter-story drift ratios within code-specified limits, owing to its combined stiffness and damping contributions. In terms of energy dissipation, the total cumulative energy dissipated by FVDs is 39.4–67.6% higher than that of SDs under the same ground motions, with added damping ratios averaging 2.42% for FVDs and 2.86% for SDs. These findings suggest that FVDs are more favorable for serviceability and frequent seismic performance, while SDs exhibit better response reduction effects under rare earthquake excitations. Full article