Abstract:To address the issue of out-of-plane buckling in flat steel plate shear walls, this paper proposes a new type of cross-slanted corrugated steel plate shear wall (CCSPW) with enhanced out-of-plane buckling-restrained performance. The study aims to investigate the influence of the corrugation angle on its seismic performance. To this end, three 1/3-scaled CCSPW specimens were designed and manufactured. The experimental study was conducted using the MTS loading system, focusing on various seismic performance indicators, such as initial stiffness, bearing capacity, failure process and form, energy consumption capacity, and ductility under low cyclic loading. The results show that CCSPWs can effectively prevent out-of-plane bulging under low cyclic loading, showcasing excellent lateral bearing capacity. The cross-slanted corrugated steel plates, subject to a joint force of tension and pressure, effectively improve the initial stiffness of specimens. Notably, the CCSPW specimen with an oblique angle of 60° exhibits the greatest initial stiffness. The specimen with an oblique angle of 45° shows a bearing capacity that is 5.5% and 10% higher than those of the other two specimens, along with the highest ductility coefficient and superior ductility. Additionally, the specimen with an oblique angle of 60° displays the largest equivalent viscous damping coefficient, ranging from 2% to 5% higher than those of the other two specimens, indicating excellent energy dissipation capacity.

Abstract:To investigate the seismic response characteristics of typical valley sites, a three-dimensional finite element numerical model was developed based on the real terrain of a representative valley site in the North Tianshan region. The model was used to analyze the response characteristics of the valley site displacements, accelerations, and spectral accelerations under pulse-like and non-pulse-like ground motions. The results reveal that the dynamic response of the site is evidently influenced by the terrain, with surface displacement and acceleration being amplified as elevation increases. The displacement response in narrow valley areas is stronger than that in wide valley areas, whereas the acceleration response is weaker. A protruding mountain spur can amplify local displacement and acceleration responses, with a more pronounced effect under non-pulse-like earthquakes and a less evident impact under pulse-like earthquakes. Site displacement and acceleration responses increase as the depth of the rock and soil mass decreases. The amplification effect of shallow rock and soil mass on displacement is weakened, whereas that on acceleration is notably enhanced. The difference in surface displacement responses between the two types of earthquakes is remarkable, whereas the difference in acceleration responses is relatively small. As the PGA of the input ground motion increases, site displacement and acceleration responses increase linearly. Short-period spectral acceleration in high-altitude regions, such as mountain peaks, is significantly higher than in low-altitude areas, such as valleys. Conversely, long-period spectral acceleration is higher in low-altitude regions than in high-altitude areas. In narrow valley areas, long-period spectral acceleration is notably higher than in wide valley areas. Therefore, when planning engineering construction in valley sites, reasonable planning and layout should be carried out according to the characteristics of the building structures.

Abstract:

Abstract:This study examines the discrepancies between calculated results from one-dimensional equivalent linearization soil seismic response analysis and actual strong motion records. The analysis uses data from the seismic monitoring array of site and structure (SMASS) operated by the Hebei Key Laboratory of Earthquake Disaster Prevention and Risk Assessment. Strong motion records from the Guye and Luanzhou earthquakes were analyzed, with a hypothetical bedrock input boundary set at a depth of 101 m. Ground motion results at depths of 65 and 30 m and the surface, calculated using the LSSRLI-1 program, were compared to observed data. Analysis results show the following: (1) Peak ground acceleration (PGA): While the calculated PGA trends generally match observed results, the amplification factor deviates more significantly as soil depth increases. Furthermore, the calculated soil response to ground motions with varying spectral characteristics differs from actual observations. (2) Response spectra: The difference between computed and actual response spectra increases with increasing soil depth. At 30 m depth, the computed spectra exhibit a distinct "triple-peak" anomaly not present in the observed data. (3) Characteristic periods: At shallow soil depths, the computed response spectrum shows a noticeably longer characteristic period compared to the observed spectrum. (4) Fourier spectra: Discrepancies between computed and actual Fourier spectra grow with increasing soil thickness. While both align in the low-frequency range, their trends and predominant frequencies diverge at higher frequencies.

Abstract:On December 18, 2023, an M_S6.2 earthquake occurred in Jishishan County, Gansu Province. A field investigation was conducted immediately on 15 frame structures and 24 masonry structures from nine primary/secondary schools and four educational annexes located at varying seismic intensity zones. Key findings include the following: (1) All 12 severely damaged buildings were single-story masonry structures with steel-wood roof trusses. (2) Most frame structures sustained only minor damage, whereas others exhibited moderate damage. (3) Significant damage to nonstructural components and ancillary structures was observed even in structurally intact buildings, posing risks to the evacuation safety of students and teachers. Based on an on-site investigation, this study systematically summarizes the common seismic damage patterns in educational facilities and identifies the potential safety hazards along evacuation pathways through four key zones: classrooms, corridors, staircases, and outdoor spaces. Consequently, practical recommendations are proposed, including seismic retrofitting of nonstructural components, equipment, and ancillary structures on campus to further enhance the safety and evacuation efficiency of personnel in schools after earthquakes.

Abstract:Conducting intense underground explosion tests is crucial for countries to develop, test, and evaluate strategic weapons. The resulting parameters are essential for evaluating weapon capabilities and ensuring national security. In this study, the surface deformation of the target area was monitored using DS-InSAR technology, applying 48 scenes of ERS-1/2 data collected from 1992 to 2001. Then, the Bayesian inversion framework was employed, proving effective in determining the parameters of underground intense explosions using the finite prolate spheroid model and the point compound dislocation model (pCDM). Finally, the accuracy and reliability of both models were analyzed and compared. The results indicate that DS-InSAR technology could effectively detect surface deformation resulting from intense underground explosions. The single-and dual-source finite prolate spheroid models, as well as the pCDM, provided a good fit to the InSAR observations, with the latter offering a superior fit. The results also demonstrate that parameter inversion of geological models based on InSAR data can provide valuable technical support for the study of underground intense explosion tests.

Abstract:Despite the lack of a robust theoretical foundation, the horizontal-to-vertical spectral ratio (HVSR) method of microtremor Fourier amplitudes has become a widely used tool for estimating site parameters and analyzing seismic site effects. This study refines the microtremor HVSR approach and introduces a novel empirical method for estimating the surface/borehole acceleration spectral ratio (SBSRa) under ground motions. The proposed method facilitates the estimation of ground motion amplification factors using in situ microtremor observations, offering critical data for seismic site effect research. Drawing on 296 958 strong motion acceleration records from 699 stations in Japan's KiK-net network, stable microtremor HVSRs were extracted from pre-event microtremor data (prior to P-wave arrivals). Statistical analysis revealed a strong correlation between microtremor HVSR and SBSRa under weak ground motions, with their spectral shapes and predominant frequencies showing high consistency. Using a frequency normalization approach, empirical correction coefficients were derived for various types of microtremor HVSR, leading to the development of a practical method for predicting SBSRa based on microtremor HVSR. Reliability analyses demonstrated that the predicted SBSRa achieves engineering-level accuracy, with Jaccard similarity coefficients exceeding 0.58 for more than 75% of the stations. These results validate the effectiveness of microtremor HVSR as a reliable proxy for approximating SBSRa under weak ground motions.

Abstract:Based on two periods of global navigation satellite system (GNSS) data (2009-2013 and 2015-2019), the Tdefnode negative dislocation method was employed to invert the locking degree and slip deficit rate of the Lintan-Dangchang fault before the Minxian-ZhangxianMS6.6 and Xiahe MS5.7 earthquakes. Combined with the spatial distribution of small earthquakes and GNSS profile results, this study analyzed the characteristics of small earthquake activity and horizontal crustal movement before the two earthquakes and evaluated the future seismic hazard of the Lintan-Tanchang fault. The results show the following: (1) The seismogenic zones of the fault exhibited strong locking states before both earthquakes, with inverted locking depths generally consistent with the focal depths, and the slip deficit rate of the fault was relatively low. (2) Combined with the spatial distribution of small earthquakes, seismic quiescence periods were observed before both earthquakes, and the duration of these quiescence periods was consistent with the aftershock distribution lengths. (3) GNSS profiles across the Lintan-Dangchang fault indicated that the fault currently exhibits thrust-dominated compression with sinistral strike-slip movement, and the fault slip rates were enhanced after the earthquake compared with those before the earthquake. Integrated analysis reveals stronger locking and high slip deficit rates in the eastern Lintan segment than in the Minxian-Dangchang segment and the eastern Hezuo segment. As these locked zones also experienced seismic quiescence periods, attention should be focused on these two regions in future endeavors.

Abstract:An M_S5.2 earthquake occurred in Longyang District (24.91°N, 99.26°E), Baoshan City, Yunnan Province, on May 2, 2023, disrupting the relative seismic calm in Baoshan City, which had not experienced any MS≥5.0 earthquakes since 2015. Based on field investigations of disaster losses and the collection of disaster data, this study provides a detailed analysis of the seismogenic geological structure, focal mechanism, spatial distribution of seismic intensity, and the earthquake damage characteristics and causes in buildings and engineering structures in the Longyang area. Additionally, the earthquake damage matrix for buildings in the affected area was compared with the damage characteristics of historical earthquakes of similar magnitude in Yunnan Province. Results show that the epicenter of Longyang M_S5.2 earthquake is located in the middle segment of the Lancang River fault zone, with right-lateral strike-slip, which is consistent with the result of the focal mechanism solution. The maximum intensity is Ⅵ degree, and the affected area is approximately 600 km2. The intensity circle presents an irregular ellipse with a long axis of 37 km and a short axis of 21 km. The long axis direction of the isoseismic line is NNW, aligning with the strike of the Lancang River fault, which is closest to the epicenter of the earthquake. Nine people were slightly injured in the earthquake, a number higher than typically seen in historical earthquakes of similar magnitude in Yunnan Province. The seismic performance of civil structure houses was poor, with notable damage observed. Due to site effects and the fact that some brick-concrete and frame structures were not constructed in accordance with specifications, the damage to houses in the area where the Wayao Town Government is located reached a severity level of VII. Traffic, communication, and water conservancy facilities were damaged to different degrees, with traffic infrastructure suffering the most severe damage. Given the extensive damage, high casualties, serious building destruction, and significant economic loss caused by this earthquake, the study offers emergency response recommendations. These suggestions aim to improve earthquake prevention, disaster reduction, and emergency rescue capabilities in western Yunnan, providing valuable reference for future preparedness and response strategies.