Earthquakes can damage transmission system components, leading to extensive blackouts and disrupting essential societal functions. In urban areas, interruptions in power supply critically impact sectors such as industry, healthcare, and telecommunications, highlighting the need for quantitative and systematic analysis. Most existing research has focused on assessing seismic fragility at the individual facility level, with insufficient probabilistic safety evaluations that consider the connectivity of entire transmission systems. This study aims to quantify the connectivity-based seismic fragility and risk associated with transmission systems in Busan and its neighboring regions, Ulsan and Gyeongnam. To achieve this, a network model of Busan’s transmission system was developed using OpenStreetMap data. Damage probabilities were calculated using seismic fragility curves from HAZUS and reports from the Ministry of the Interior and Safety. Damage state-specific risks were then quantitatively assessed by combining these fragility values with Busan’s seismic hazard curves. The results showed High Confidence and Low Probability of Failure values ranging from 0.049 g (Slight) to 0.273 g (Complete), with median fragility values ranging from 0.143 g (Slight) to 0.605 g (Complete). The annual risk for each damage state was determined to be 4.151×10-4/yr, 1.177×10-4/yr, 3.667×10-5/yr, and 9.391×10-6/yr. This research quantitatively assesses the seismic fragility of Busan’s transmission system, providing a practical basis for disaster response strategies and risk-informed decision-making related to regional electric power infrastructure.
Current seismic design provisions prohibit the use of a weak panel zone from using special moment frame (SMF) connections due to concerns that large deformations in these zones may lead to brittle connection failures. However, several experimental studies have demonstrated that moment connections with weak panel zones can exhibit adequate ductility and energy dissipation capacity for SMF connections. This study aims to investigate the impact of weak panel zones on the seismic performance of SMFs utilizing welded unreinforced flange-welded web (WUF-W) connections, as outlined in AISC 358-22. The analysis will consider both four-story and twelve-story SMFs. Each frame will be modeled with either strong or weak panel zones. The findings indicate that SMFs with weak panel zones demonstrate greater ductility and collapse strength compared to their counterparts with strong panel zones.
The abstract should clearly state the purpose and nature of the investigation while summarizing the key conclusions in English only. It should be a single paragraph consisting of no more than 200 words. This study presents a method to enhance the seismic performance of a stacked stone pagoda by utilizing a Ball Vibration Absorber (BVA). The governing equations of motion for sliding, the primary failure mode of the stacked stone pagoda, were derived, and a numerical model was developed. Through various numerical analyses, the optimal design parameters of the BVA were identified to maximize its seismic control effectiveness for the pagoda. The BVA device can increase the critical seismic acceleration at which the sliding mode occurs in the structure. Moreover, the seismic control performance of the BVA improves with an increase in the mass of the sphere and the coefficient of friction between the layers. Conversely, as the applied seismic acceleration rises, the effectiveness of the BVA in controlling seismic responses diminishes, although a certain level of control effect is maintained. Finally, as long as the sphere of the BVA maintains a specific range of rolling motion, the radius of the sphere or rolling radius does not significantly impacts its seismic control performance.
Non-seismic-designed reinforced concrete (RC) pier walls often include lap splices in potential plastic hinge regions. This study develops an analytical model to capture the post-yield load–deformation response of lap-spliced RC pier walls subjected to earthquake loading. The parameters of the model were calibrated using experimental results, and linear regression was conducted to propose predictive equations for these parameters. The accuracy of the model was validated by comparing it to the load–deformation responses of specimens not included in the calibration database. Subsequently, the developed model was applied to probabilistic bridge models supported by RC pier walls. A multi-parameter seismic demand model was constructed, taking into account geometric, material, and structural uncertainties, using Lasso regression. This model achieved R² values of 0.73 for in-plane loading and 0.75 for out-of-plane loading. The improvements in performance metrics and the results of the sensitivity analysis emphasize the need to develop a multi-parameter seismic demand model to ensure more reliable seismic demand predictions.
In this study, we performed experiments aimed at improving the performance of circular Tuned Liquid Dampers (TLDs). TLDs offer numerous advantages over other passive vibration control devices. They are easy to install not only in new structures but also in existing ones, and they provide high cost efficiency compared to Tuned Mass Dampers (TMDs). Maintenance is straightforward, requiring only checks of the liquid level and inspections for any leakage. To adjust the natural frequency of a TLD for both installation and maintenance, we can simply manage the liquid level within the device. However, much of the existing research on enhancing TLD performance has focused on rectangular shapes. Therefore, we conducted experiments to investigate ways to achieve an improved damping ratio in circular TLDs equipped with internal dampers. A large number of shaking table experiments were carried out using various configurations of TLDs with dampers. We explored different arrangements of dampers and compared their performance against that of conventional TLDs.
A casualty-estimation framework has been proposed that incorporates building-scale, time-varying occupancy data (considering factors such as size, use, and time of day) into earthquake loss modeling. Information from Seumter building records is combined with KOSIS population data, and HAZUS modules are used to estimate both the baseline population and dynamic occupancy at the building level. Case studies have shown a close alignment with observed data, with no significant model flaws, indicating the framework’s operational readiness. This approach moves beyond broad administrative totals to provide micro-spatial resolution suitable for Korea’s rapid seismic attenuation and localized damage patterns. It enables accurate, time-sensitive casualty estimates. The framework is designed to be scalable to include additional data sources, such as mobility, transportation, and activity patterns. It supports effective evacuation and shelter planning, surge capacity management, and prioritization of retrofitting, leading to more efficient resource allocation. Furthermore, the framework provides a consistent method to integrate future data streams and quantify uncertainty without disrupting the core workflow.