Earthquake Engineering & Structural Dynamics最新文献

The state-of-the-practice soil-structure interaction (SSI) analysis, referred to as the substructure approach, relies on simplified models of kinematic and inertial interaction. While computationally efficient, these models often lack accuracy in estimating impedance functions and foundation input motion (FIM) due to oversimplified assumptions about the soil-structure system behavior. To overcome these limitations, this study presents a probabilistic soil-structure system identification framework based on Bayesian inference to estimate substructure model parameters and FIM using recorded structural response data. The framework consists of two steps: the first estimates superstructure parameters, and the second jointly estimates impedance function parameters and FIM, thereby mitigating bias due to parameter interdependencies. The framework is applied to the Garner Valley soil-foundation-structure-interaction test facility using two recorded seismic events for parameter estimation and a third for validation. The validated model demonstrates reasonable predictive capability. When applied across multiple soil-structure systems, this framework can inform improved SSI modeling and analysis practices, leading to more accurate seismic response predictions for structural systems.

Accurate seismic risk assessment can be computationally intensive, requiring numerous nonlinear analyses to propagate uncertainties. Surrogate models offer an efficient alternative via emulating the costly structural models. For earthquake engineering applications, a practical strategy to promote efficient emulation is to employ explanatory variables (seismicity characteristics, ground motion features, or their combination) as explicit surrogate inputs, while simultaneously treating the inherent aleatoric variability in ground motion acceleration time-series as latent surrogate model input variables. This results in aleatoric uncertainty in the engineering demand parameter (EDP) predictions, which cannot be captured by standard deterministic surrogates. Stochastic emulation overcomes this challenge by establishing a stochastic input–output mapping to account for the aleatoric uncertainties in the EDP distributions. This study introduces the use of mixture density networks (MDNs) to approximate EDP distributions. Key advantages of MDN are its compatibility with non-replicated training samples and its inherent scalability to high-dimensional inputs, allowing for an easier incorporation of full ground motion features, a significant advantage over many state-of-the-art surrogates. Case studies on two representative structures, evaluated with three different stochastic ground motion models, demonstrate that the proposed MDN-based approach outperforms established stochastic surrogate workhorses. It provides more accurate seismic risk estimates at a substantially lower computational training cost, highlighting its practical utility for complex, real-world seismic applications.

The displacement and acceleration response are the key parameters in the seismic evaluation and design of a multilayer suspended thyristor valve. Meanwhile, the Rayleigh damping model, although popular for buildings and bridges, may underestimate the acceleration responses due to the high damping ratio in high-frequency ranges, as the suspension structure is significantly affected by high-order modes. This study investigates the damping source of the multilayer suspended thyristor valve, a scale-down model was constructed to obtain the equivalent damping ratios of several modes under seismic inputs. As the friction in the joints, other than the aerodynamic force, is the primary source of damping, the friction model is proposed to describe the energy dissipation behavior under earthquakes. An analytical model is established to validate the accuracy of the proposed model, and a detailed finite element model is founded to investigate the influence of the friction model. The friction model can correctly estimate the high-frequency range response, it is recommended to use the friction model in seismic evaluation of acceleration response of suspended thyristor valves. In addition, the equivalent damping ratio decreases with the pulled distance in the snap-back test, so the pulled distance is recommended to be no less than the estimated peak seismic displacement response.

This study investigates the seismic response behaviour of wind turbines in operational conditions, highlighting how yaw misalignment and seismic input characteristics influence their dynamic performance. A novel wind tunnel-shaking table (WTST) test platform was developed to apply wind and seismic loads simultaneously. Using a 1:100 scale model wind turbine, tests were conducted with El-Centro and Taft seismic records obtained from the Pacific Earthquake Engineering Research (PEER) Strong Earthquake Database, which were adjusted in amplitude and time to simulate realistic earthquake conditions. Experiments involved four yaw conditions (yaw angle = 0°, 15°, 30° and 45°) and twelve different seismic input angles with three peak ground accelerations (PGAs) under operational conditions. The results reveal that yaw angles of a wind turbine significantly affect aerodynamic characteristics, thereby influencing seismic dynamic response. The study identifies the seismic incidence angle aligned with the turbine's yaw direction as the most critical scenario and finds that under operational conditions, seismic excitation dominates the structural response. As the yaw angle increases, nacelle displacement decreases, and acceleration rises under wind-only loading due to reduced aerodynamic damping. When wind turbines experience earthquakes during operation, displacement and acceleration responses exhibit symmetric double-peak patterns, with the peak positions shifting according to the yaw angle. The maximum displacement occurs when seismic and wind loads align with the yaw direction, while the highest acceleration arises when seismic loads oppose the wind direction. The nacelle, as the most vulnerable component, can experience acceleration amplification factors up to three, highlighting significant seismic energy concentration. These insights advance understanding of wind turbine behaviour under coupled wind and seismic excitations, offering valuable guidance for the design of resilient wind energy systems.

After an earthquake, the ductile reinforced concrete (RC) beam members in an RC building structure with seismic design may develop moderately damaged plastic hinges, and then the repair should be conducted to recover its functionality. Therefore, to investigate the seismic capacity of a ductile RC beam member with the damaged plastic hinge zone (DPHZ) after the repair is necessary. In this work, six ductile RC beam specimens are designed to obtain the seismic capacity for the repaired specimens. To let the specimens with the specified damaged levels in the plastic hinge zones, the dynamic loading test is conducted. Then, the repair methods, including surface treatment, epoxy low-pressure injection, and epoxy resin mortar coating, are applied according to the different damage levels of each specimen. Finally, the test results related to strength, stiffness, and energy dissipation are used to quantify the pre- and post-earthquake seismic capacity of a ductile RC beam with the repaired DPHZ, that is, the reduction factors. Additionally, this work also investigates the application of the prediction models suggested in ASCE/SEC 41 for the force–deformation curve on the ductile RC beams with the repaired DPHZ.

Self-centering (SC) precast concrete wall structure is one of the effective systems to enhance seismic resilience within the low damage structures community, which fulfills the demand for low damage and high cost-effectiveness. Most past studies have focused solely on the structural level, for example, on general seismic performance, the influence of different energy dissipation devices, and design methods. Little attention is paid to the coordination between SC wall and non-structural components, such as infill walls, the latter of which plays an essential role in terms of achieving the integral seismic resilience of buildings. To this end, this study reports on the experimental results of SC wall structures incorporating various innovative infill walls. The primary objective of the proposed new infill walls is to coordinate the deformation between the structural skeleton and infill walls, thereby fostering an integrated seismic resilient structural system that is promising in earthquake-prone areas. Moreover, the study explores the effectiveness of energy dissipators equipped between infill wall panels. One of the purpose of using addition damper in infills is to reduce energy dissipation demand for SC walls while preserving ease of replacement. The outcome of test results covers various aspects, including force–displacement relationships, degradation of structural performance indexes, residual displacement, response of slotted beams, energy dissipation, and some detailed results for the SC wall. Results indicate that the tested specimens incorporating infill walls exhibit great seismic performance in terms of achieving low damage and self-centering behavior as expected. The inclusion of dampers between infill wall panels enhances energy dissipation capacity for structure. Notably, specimens equipped with U-shaped steel dampers and viscoelastic dampers demonstrate significant improvements to energy dissipation capacity, as increased by 32.1% and 22.4% under design target displacement, respectively, compared with those without dampers.