Earthquake Engineering

• Research progress on seismic resilience assessment and enhancement of tunnel engineering

  SUN Weiyu, WU Xiaole, ZHU Hui, WANG Bo, ZHONG Wenshuai, LIANG Qingguo

  2026,48(5):1001-1017, DOI: 10.20000/j.1000-0844.20251121002

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  Abstract:

  Seismic resilience of tunnels is a core research topic in underground engineering disaster prevention and mitigation. The concept of seismic resilience offers a new paradigm for seismic safety analysis and performance optimization of tunnel systems. This article systematically reviews the assessment methods and enhancement strategies of seismic resilience in tunnel engineering. First, it expounds on the evolutionary process of the concept of seismic resilience from the ecological field to the engineering field and clarifies the core connotation of tunnel seismic resilience: the ability to resist seismic hazards and rapidly restore structural functions. Second, it systematically generalizes the mathematical models and scenario-based engineering evaluation frameworks for resilience assessment and constructs a technical system for evaluating tunnel seismic resilience. Further, from the two dimensions of resistance and recovery resilience, it explores the technical measures to enhance the damage resistance of tunnel bodies and their interfaces and design strategies to improve the efficiency of post-earthquake functional recovery. Finally, the limitations of existing studies are highlighted in terms of model applicability, multihazard coupling effects, and life cycle cost analysis, and the development trends toward intelligentization and systematization are prospected. This article is intended to provide a systematic reference for the theoretical advancement and engineering practice of seismic resilience in tunnel engineering.

• Deformation characteristics and failure prediction model for saturated soft clay under cyclic loading

  LAN Jingyan, LI Zhehan, LUO Chaorong, XIAN Ganling, MO Hongyan

  2026,48(5):1018-1027, DOI: 10.20000/j.1000-0844.20250109001

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  To investigate the failure characteristics and influencing factors of soft clay under dynamic loading, and to estimate and predict the deformation development and number of cycles to failure, this study conducted a series of undrained dynamic triaxial tests on remolded saturated soft clay. The effects of confining pressure, cyclic stress ratio (CSR), and number of cycles on axial strain were examined, and a relationship model between cumulative strain and the number of cycles to failure was established. The results show that cumulative plastic deformation can be classified into three types: stable, critical, and failure. When the CSR exceeds the critical cyclic stress ratio, a pronounced strain inflection point appears in the axial strain versus number of cycles curve, indicating failure of the soil structure; this critical value decreases with increasing confining pressure. Based on the dynamic triaxial test results, the cumulative plastic deformation was described in two stages separated by the strain inflection point, and a prediction model for the number of cycles to failure of saturated soft clay, considering the effects of CSR and confining pressure, was established. The model was validated using test results from Xiaoshan soft clay. The results indicate that the proposed prediction model has good applicability for practical engineering.

• Seismic safety and resilience of shear wall structures in high-intensity areas under different drift ratio limits

  JI Jing, SU Guoqiang, LIN Jingcong, WU Zinan, HAN Xiaolei

  2026,48(5):1028-1039, DOI: 10.20000/j.1000-0844.20240423003

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  In high-intensity areas, structures designed according to the elastic story drift ratio limit specified in the national standard Technical Specification for Concrete Structures of Tall Buildings often require numerous vertical components with large cross-sectional dimensions, which adversely affect building functionality and economy. To investigate the rationality of relaxing the story drift ratio limit as recommended in a group standard—Standard for Performance-based Seismic Design of Building Structures —three shear wall structures with progressively reduced stiffness were designed based on the standards, considering the high-intensity region of Kashgar, Xinjiang, as an engineering case study. This study compared the overall structural, economic, and carbon emission indices of the three structures. Further, a deformation-based structural seismic performance evaluation method was employed to quantify the structural component damage level and repair cost under rare earthquakes. The results indicate that all three structures exhibit desirable yielding mechanisms and satisfactory seismic resilience under rare earthquakes; meanwhile, the structures designed with relaxed story drift ratio limits demonstrate superior economic efficiency and carbon reduction benefits. The elastic story drift ratio limit for shear wall structures in high-intensity areas can be relaxed to 1/500 under frequent earthquakes.

• Experimental study on the stability of full-scale viscoelastic dampers

  ZHAO Xuelian

  2026,48(5):1040-1051, DOI: 10.20000/j.1000-0844.20241223001

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  Recent post-earthquake investigations have revealed that instability failure of dampers can cause severe engineering losses. Conventional viscoelastic dampers (VEDs), fabricated by vulcanizing steel plates and viscoelastic material in alternating layers, dissipate energy through shear deformation of the viscoelastic material caused by the relative movement of the steel plates. However, their high height-to-thickness ratio renders them susceptible to out-of-plane instability under complex practical loading conditions. To overcome this limitation, a novel VED with enhanced out-of-plane stiffness is proposed. Full-scale tests were conducted on both the proposed and conventional VEDs, encompassing basic mechanical performance tests, stability tests, and out-of-plane static pushover tests. The mechanical properties and out-of-plane stability of the two damper types were systematically compared. The results demonstrate that the critical load, critical frequency, and instability mode of the conventional VED agree well with numerical simulations. Moreover, the proposed VED exhibits an out-of-plane stiffness 11-15 times greater than that of the conventional VED, confirming its excellent stability. This study provides an experimental foundation for the engineering application of the proposed VEDs.

• Macroscopic particle size analysis and fractal study of the disintegration process of red-bed mudstone

  YU Yunyan, ZHANG Binbin

  2026,48(5):1052-1063, DOI: 10.20000/j.1000-0844.20240701003

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  Disintegration characteristics of red-bed mudstone pose a serious threat to the construction, management, and maintenance of engineering works in red-bed areas. To better understand these characteristics, naturally air-dried red-bed mudstone from the Lanzhou area of Gansu Province was selected as the research object. Indoor disintegration cycle tests were carried out under three conditions: combined dry-wet and cold-hot cycles, dry-wet cycles alone, and cold-hot cycles alone. At the end of each cycle, the samples were sieved to obtain the particle mass of each size fraction. On this basis, fractal theory was applied to calculate the grain-size fractal dimension during the disintegration process, thereby determining the fractal dimension at which the disintegration of red-bed mudstone tends to stabilize. The results showed that under the same water content and the same number of disintegration cycles, the combined dry-wet and cold-hot group exhibited the most severe disintegration, followed by the dry-wet cycle group, whereas the cold-hot cycle group showed no disintegration. With increasing water content, the particle mass of each size fraction of disintegrated red-bed mudstone exhibited four types of variation patterns, and the disintegration process underwent an abrupt acceleration when the water content reached 30%?40%. With an increasing number of disintegration cycles, the disintegration process of red-bed mudstone tended to cease when the grain-size fractal dimension reached 2.7?2.8.

• Seismic fragility analysis of continuous girder bridges isolated with STFPB

  LI Ximei, GUO Pengyi, SU Runtian, MU Bohai

  2026,48(5):1064-1072, DOI: 10.20000/j.1000-0844.20240402002

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  The novel shape memory alloy-triple friction pendulum bearing (STFPB) is an advanced seismic isolation device that incorporates shape memory alloy (SMA) cables into conventional triple friction pendulum bearings (TFPBs). This study elucidates the design principle and structural configuration of STFPB and analyzes the factors influencing its performance. Results indicate that for optimal STFPB design, the effects of cable diameter on stiffness and energy dissipation capacity must be considered. Appropriately increasing SMA cable quantity effectively enhances stiffness and energy dissipation. A three-span continuous girder bridge model is simulated using the finite element software ABAQUS for seismic time-history analysis, and the fragility curves for piers and bearings are derived through fragility assessment. Findings reveal that STFPB exhibits superior seismic isolation performance to TFPB. Under strong earthquakes, STFPB effectively protects the main girder from excessive damage by leveraging its robust self-centering capability and high energy dissipation capacity.

• Testing and performance analysis of a self-centering unidirectional friction damper

  LIU Yunshuai, LI Bingrui, HAN Jianping, LU Wenhui

  2026,48(5):1073-1082, DOI: 10.20000/j.1000-0844.20241108003

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  Abstract:

  To reduce residual deformation in friction dampers after earthquakes, a self-centering unidirectional friction damper (SCUFD) with adjustable friction force is proposed. The structure and working principle of the SCUFD are described in detail, and experimental tests and numerical simulations are performed. Comparison of the experimental data with the numerical simulation results confirms the applicability and accuracy of the finite element model. Using this model, parametric studies are conducted on the friction coefficient between the cylinder and friction blocks, the friction coefficient between the wedge-shaped sliders and the piston, and the return spring preload to investigate their effects on the hysteretic performance of the SCUFD. The results indicate that increasing the friction coefficient between the cylinder and friction blocks enhances the maximum output force and energy dissipation capacity of the SCUFD but does not affect its self-centering capacity. Increasing the friction coefficient between the wedge-shaped sliders and the piston does not alter the maximum output force but increases the second-stage stiffness and decreases the sixth-stage stiffness, thereby improving energy dissipation capacity while reducing self-centering capability. Both the maximum output force and self-centering capacity increase with greater return spring preload, whereas the energy dissipation capacity remains unchanged.

• Collapsible deformation of the Ili loess under varying degrees of Humidification

  MI Wenjing, ZHANG Aijun, LIANG Zhichao

  2026,48(5):1083-1094, DOI: 10.20000/j.1000-0844.20241206001

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  Collapsibility is a major cause of structural damage in loess regions. Investigating the collapsible deformation of loess under varying degrees of humidification can offer more effective guidance for engineering practice. In this study, Ili loess from Xinjiang was selected as the research subject, and indoor compression tests along with other methods were used to analyze the effects of water content, dry density, and depth on the collapsible deformation characteristics of Ili loess. Humidification collapse tests were also conducted to examine the humidification deformation behavior of loess at different humidification levels, as well as the relationship between the humidification collapse amount and saturated collapse during the humidification process. The results indicate the following: (1) The collapsibility coefficient of Ili loess is linearly and inversely proportional to dry density and varies nonlinearly with water content. (2) An expression for the humidification deformation coefficient calculated from the humidification level fits the collapsibility coefficient curve well, and the curve reflects the actual decrease in the collapsibility coefficient with increasing overburden pressure. (3) The relationship curve between the humidification level and the ratio of humidification collapse to saturated collapse approximately follows a power function, which effectively captures the variation of humidification deformation of the soil with water content. These findings provide a reference for loess engineering construction and research in Ili and other regions.

• Experimental study on the influence of reinforcement and cement improvement on the seismic performance of silt subgrade

  LIU Ze, XU Chudong, YAN Wenqin, SU Weiwei, LI Jigang

  2026,48(5):1095-1103, DOI: 10.20000/j.1000-0844.20240719002

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  To verify the feasibility and effectiveness of using silt as subgrade fill in regions with high seismic fortification requirements, three model types were designed and fabricated: plain silt subgrade, reinforced silt subgrade, and 4% cement-improved silt subgrade. The failure characteristics and dynamic response patterns of the three schemes were investigated through shaking table tests, and measures to enhance the seismic performance of silt subgrade in high seismic fortification areas were explored. The results indicate that the plain silt subgrade progressively underwent cracking, crushing, and subsidence failure after the peak seismic acceleration reached 0.25g. Both the reinforced silt subgrade and the 4% cement-improved silt subgrade exhibited superior seismic resistance. When the loading on the reinforced silt subgrade reached 0.325g, and that on the 4% cement-improved silt subgrade reached 3.5g, cracks appeared in both models, yet they maintained good structural integrity. The acceleration amplification factor within the three subgrade models decreased with increasing seismic load, whereas the dynamic earth pressure increased nonlinearly with increasing load. When cracks and damage appeared in the subgrade, the acceleration amplification factor decreased markedly, and the dynamic earth pressure also decayed. Provided that construction quality is ensured, using plain silt for subgrade filling can satisfy seismic fortification requirements. Reinforcement and cement improvement are effective approaches for enhancing the seismic performance of silt subgrade and can be prioritized in regions with high seismic fortification demands.

• Soil pressure at the top of trench-buried pipelines under differential thaw settlement of permafrost foundations

  WANG Fei, QIAN Yulong, LI Guoyu

  2026,48(5):1104-1114, DOI: 10.20000/j.1000-0844.20241111001

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  To clarify the influence of differential thaw settlement of permafrost foundations on soil pressure at the top of trench-buried pipelines, the soil arching effect induced by relative displacement of the backfill soil is introduced based on Marston's theoretical model of soil pressure on trench-buried pipelines. The circular arc minor principal stress trajectory method is used to determine the lateral earth pressure coefficient of the backfill. A quantitative relationship between the principal stress rotation angle and the thaw settlement of foundation permafrost is established. By combining the inclined thin-layer element method, an equation for calculating the soil pressure at the pipe top is derived, and a computational model for soil pressure at the pipe top under non-cooperative thaw settlement between the pipeline and the permafrost is proposed. Through indoor model test validation and parameter sensitivity analysis, the method is shown to accurately characterize the variation of soil pressure at the pipe top during different stages of permafrost thaw settlement. The thaw settlement of foundation permafrost has a considerable influence on the soil pressure at the pipe top: the coefficient of soil pressure at the pipe top is approximately linearly and positively correlated with the relative thaw settlement of the foundation, with a maximum increase of 41%. As the angle between the differential thaw settlement surface and the horizontal plane increases, the coefficient decreases linearly, with a maximum reduction of 14%. The coefficient increases approximately hyperbolically with the trench-to-pipe width ratio (B/D), and B/D = 4 can serve as the boundary value between trench-buried and aboveground pipelines at different thaw settlement stages. As the burial depth-to-pipe width ratio (H/D) increases, the coefficient initially increases and then stabilizes. For deeply buried pipelines, the backfill in the trench is more likely to form a complete soil arch during thaw settlement, and the influence of thaw settlement on the soil pressure at the pipe top is more pronounced. These findings can provide theoretical support for the assessment of thaw settlement hazards affecting buried pipelines in permafrost regions.

• Seismic dynamic response of a tunnel near valleys under non-uniform excitation

  ZHU Hui, SUN Weiyu, YAN Songhong, OU Erfeng, LI Jing, LIANG Qingguo, ZHANG Jian

  2026(5):1115-1124, DOI: 10.20000/j.1000-0844.20250801001

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  Valley topography produces a pronounced seismic amplification effect that can severely compromise the seismic performance of large infrastructure at the site. To investigate the influence of valley topography on the seismic dynamic response of a nearby tunnel, a seismic wave input method based on viscoelastic artificial boundaries was used to apply non-uniform excitation of SV waves at different incident angles. Considering various relative positions between the tunnel and the valley, multiple valley site models, including circular, trapezoidal, and V-shaped configurations, were established for nonlinear dynamic time-history analysis. A complete site model without the valley topographic effect served as a reference to systematically analyze the influence of valley topography on the acceleration distribution, acceleration amplification factor, and lining stress of the nearby tunnel. The results indicate that valley topography markedly amplifies the acceleration response of the tunnel lining. As the seismic wave incidence angle increases, the acceleration amplification effect progressively strengthens, with the maximum amplification factor reaching 1.69. The intensity of this amplification effect depends on the valley geometry: the trapezoidal valley exhibits the strongest amplification, followed by the circular valley, whereas the V-shaped valley produces the weakest effect. The relative position of the tunnel with respect to the valley also governs the acceleration amplification effect on the lining. When the tunnel is located in front of the valley, the lining acceleration is markedly amplified at all seismic wave incident angles. When the tunnel is located behind the valley, the lining acceleration is amplified only under vertical incidence; oblique incidence weakens the valley's topographic effect. The lining stress response at the arch shoulder on the valley side and at the arch foot on the opposite side is strongly influenced by valley topography and warrants particular attention in seismic fortification design.

• Influence of the SCI effect on dynamic response characteristics of ground fissure sites

  SUN Pushuo, DENG Yahong, MU Huandong, MEN Huan, TIAN Wei

  2026,48(5):1125-1135, DOI: 10.20000/j.1000-0844.20241111002

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  Under earthquake action, complex interactions occur between urban building groups and the underlying site, known as the site-city interaction (SCI) effect. How the SCI effect influences the dynamic response characteristics of ground fissure sites remains unclear. Therefore, taking the Xi'an ground fissure as the research background, a series of numerical models were established considering frame structures with different foundation types, natural frequencies, and building densities to investigate the SCI effect on the dynamic response of ground fissure sites. The results indicate that the SCI effect reduces both the site response and the influence range of the ground fissure. When the natural frequency of the building structures matches that of the ground fissure site, the SCI effect markedly reduces the site response. When the natural frequency of the buildings matches the predominant frequency of the seismic waves, the response at some measurement points on the ground fissure site increases. However, owing to the SCI effect, the average response of the entire site still decreases. Therefore, in urban construction, the avoidance distance for ground fissures can be appropriately reduced, while resonance phenomena should be avoided as much as possible.

• Particle flow simulation of seismic subsidence deformation characteristics in loess

  CHEN Jiaqi, WEI Tingting, WU Zhijian

  2026,48(5):1136-1145, DOI: 10.20000/j.1000-0844.20250207001

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  This study developed a dynamic triaxial test model for loess using the PFC3D particle flow simulation method in conjunction with laboratory dynamic triaxial tests. Through sensitivity analysis of contact bond strength, stiffness ratio, and friction coefficient, the mesoscopic parameters of the numerical specimen were calibrated. The validity of the numerical model was verified by comparing seismic subsidence curves from laboratory tests and numerical simulations. The seismic subsidence characteristics of loess under dynamic loading were then investigated from three perspectives: stress field, displacement field, and rotation field. The results indicate that seismic deformation resistance of loess specimens is positively correlated with contact bond strength and friction coefficient, and negatively correlated with stiffness ratio. With increasing confining pressure, the seismic subsidence coefficient decreases, and the convergence of axial cumulative strain becomes more stable, which is microscopically manifested as increased interparticle contact forces accompanied by decreased particle displacement and rotation. With increasing dynamic stress amplitude, the axial cumulative strain increases and weak interparticle bonds sustain damage, causing the contact force to first increase and then decrease, while particle displacement and rotation increase correspondingly.

• Applicability of a three-factor dynamic stress reduction coefficient model in the evaluation of loess seismic subsidence

  YU Haoran, WANG Ping, WANG Huijuan, PU Xiaowu, ZHONG Xiumei, ZHANG Xingfu, DONG Yanpu

  2026,48(5):1146-1155, DOI: 10.20000/j.1000-0844.20260327001

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  To address the issue of large deviations in the traditional dynamic shear stress reduction coefficient (r_d) model for predicting earthquake-induced settlement in loess sites, the three-factor r_d calculation method is introduced to loess sites for the first time. The study indicates that depth (D), magnitude (M), and the 12-m equivalent shear wave velocity (v_s,12^*) are the three most significant factors affecting r_d. Therefore, based on measured borehole wave velocity data from 48 typical sites on the Loess Plateau, the SOILQUAKE program was used to conduct equivalent linear site response analysis, and a three-factor r_d model incorporating the three significant factors was introduced and verified through comparison with traditional methods. This model has a continuous curve form within the depth range of 0-30 m in thick loess sites, overcoming the shortcoming of traditional methods that rely on depth interpolation and splicing. The model reasonably reflects the physical laws that the r_d curve shifts leftward and rises with increasing magnitude, and tends to become straighter with increasing shear wave velocity. In validation at a typical site in Lanzhou, the predicted seismic subsidence of this model remained within 1.3 to 1.8 times the SOILQUAKE benchmark value, whereas the traditional method sharply increased from 2.0 times to 8.3 times, exhibiting significant non-physical growth. In the hazard assessment of the 2023 Jishishan M6.2 earthquake, the model's predictions were generally consistent with the field investigation scope, preliminarily verifying the model's applicability. This method only requires conventional investigation to obtain v_s,12^* and can quickly generate an r_d profile, greatly reducing data requirements and computational costs, thus providing an economically feasible technical solution for rapid earthquake disaster assessment in loess regions.

• Static stability and natural frequency characteristics of a multi-strut aluminum alloy suspen-dome structure

  DUAN Zhicheng, Lü Hui, DONG Shilin, FENG Ruoqiang, WANG Shiquan, KANG Yuting, CHEN Yuwen

  2026,48(5):1156-1168, DOI: 10.20000/j.1000-0844.20250417001

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  To expand the structural forms of suspen-domes and improve their structural stability, the prestressed cable-strut system of the multi-strut cable dome was applied to an aluminum alloy single-layer latticed shell to form a multi-strut aluminum alloy suspen-dome. The mechanical properties of this structure were investigated, and its overall feasibility was evaluated. The optimal structural topology was determined by comparing the static performance, stability, and economy of three topological configurations: drum-honeycomb four-strut type Ⅰ , type Ⅲ , and pentagonal three-strut type. Using ANSYS finite element software, the internal forces in cables and struts and the vertical displacements of joints in the optimal structure under various load cases were analyzed. The influence of different parameters, including rise-to-span ratio, thickness-to-span ratio, prestress level, arrangement scheme of lower chord joints, and span, on the stiffness, ultimate bearing capacity, and natural vibration characteristics of the optimal structure was further studied. The results show that the drum-honeycomb four-strut type Ⅲ structure exhibits the best overall performance. Its ultimate bearing capacity is 8.9% and 25.6% higher than that of type Ⅰ and the pentagonal configuration, respectively, and its steel consumption is the lowest. This optimal structure is relatively sensitive to temperature loads, half-span uniformly distributed loads, and pin-jointed connections. Its natural frequencies are relatively concentrated, and most of its vibration modes are symmetric. The optimal ranges of key design parameters (such as rise-to-span ratio and thickness-to-span ratio) were determined, providing a theoretical basis and practical recommendations for the selection and stability design of aluminum alloy suspen-dome structures.

• Experimental study on the hysteretic performance of a novel damping steel U-shaped damper

  LI Wenxuan, LI Bin, WU Chengliang

  2026,48(5):1169-1177, DOI: 10.20000/j.1000-0844.20241217001

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  U-shaped dampers are efficient energy dissipation devices that have been widely used in various engineering applications. To improve the damping performance of U-shaped dampers in seismic isolation structures, a novel damping steel with superior mechanical properties was used to fabricate the dampers. The material properties, including yield strength, tensile strength, and elastic modulus, were determined. Five U-shaped dampers made of this novel damping steel were manufactured, and hysteretic performance tests were conducted. The test results indicate that under cyclic loading, the dampers exhibit stable hysteretic behavior and full hysteretic loops. Based on these findings, a finite element model of the U-shaped damper was developed to simulate its mechanical behavior under cyclic loading. The effects of plate thickness, plate width, plate spacing, and the length of the straight segment of the fillet on damper performance were then investigated. The parametric analysis results indicate that the U-shaped damper made of the novel damping steel possesses excellent mechanical properties and favorable hysteretic performance, providing a reference for the optimal design of such dampers.

Earthquake Research

• Reconstruction of the apparent stress field in the Anqiu—Juxian section of the Tan-Lu fault zone based on fractal theory

  SUN Qiang, ZHANG Zhengshuai, YANG Le, LI Wei, WANG Peng

  2026,48(5):1178-1188, DOI: 10.20000/j.1000-0844.20250925001

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  Apparent stress is an estimate of the average crustal stress within a region. In this study, the stress field of the Anqiu—Juxian section of the Tan-Lu fault zone is reconstructed using fractal interpolation based on apparent stress data to identify potential anomalous zones within the stress field through fractal theory. The study mainly addresses the following issues: first, the shear stress increment is calculated using a relevant algorithm, and the conversion formula between shear and apparent stress is applied to supplement apparent stress data points, thereby solving the sparsity and uneven distribution of the original data. Second, multifractal theory is employed to calculate the singularity index, delineating stress enrichment, depletion, and background zones in the study area. Additionally, a fitting method is proposed for the singularity index versus b-value, as well as the c-value versus b-value. Through this fitting, the singularity index and c-value in unknown areas are obtained under the background b-value, and the relationship between apparent stress and the b-value is also derived. Third, fractal interpolation is used to reconstruct the apparent stress field in the study area. An interval of three data points is selected to ensure the accuracy of fractal interpolation and an effective equivalent representation of the original data. The apparent stress distribution reconstructed by fractal interpolation shows a gradual increase from south to north, with maximum and minimum values of 3.17 and 0.008 MPa, respectively. The areas near Juxian County and north of 36.05°N (except the Changle area) exhibit relatively high apparent stress values. The fractal-interpolated apparent stress distribution reveals more details of the anomalous stress distribution.

• Bitmap-based method for assessing seismic waveform data continuity and its application

  WANG Chuang, LIU Wei, JIN Yuan, ZHOU Cong, CHAI Xuchao, WANG Wenqing

  2026,48(5):1189-1196, DOI: 10.20000/j.1000-0844.20240410001

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  Data continuity is a crucial metric for evaluating the quality of seismic waveform data. Current methods for assessing seismic waveform data continuity often face challenges such as excessive file segments or irregular arrangements among data segments, leading to significant time consumption or algorithm failure. To address these issues, this study introduces a bitmap-based method for evaluating waveform data continuity. This method constructs bitmap vectors to represent the recording and overlapping statuses by mapping data sampling points into bits. The constructed bitmap vectors effectively capture the continuity of data recording within the assessment time window and eliminate the impact of disordered or overlapped data segments from a data structure perspective. This approach enables rapid and accurate calculation of continuity metrics. Experimental results in real-world scenarios demonstrate the method's superior performance, robustness, and practical value for conducting reliable continuity assessments on waveform data from the China seismic network.

• Quaternary activity of the Huliuhe fault in the Yuguang Basin based on shallow seismic reflection

  PENG Yuanqian, GAO Wuping, RAN Zhijie, WEN Chao, LUO Yanxin

  2026,48(5):1197-1209, DOI: 10.20000/j.1000-0844.20240729001

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  The Huliuhe fault, a component of the Zhangjiakou—Bohai tectonic belt, is a notable fault within the basin-range tectonic region of northwestern Beijing. Several moderate-to-strong earthquakes have occurred near this concealed fault. To date, the Huliuhe fault remains underexplored, with its Quaternary activity still poorly understood. In previous projects, three shallow seismic survey lines were deployed to investigate the fault. This paper presents a detailed processing and analysis of data from these survey lines. By integrating regional Quaternary stratigraphic data, particularly Quaternary borehole data within 3.5 km of the survey lines, the Quaternary activity of the Huliuhe fault is characterized. The results show that the fault consists of a Y-shaped structure formed by a main fault, as well as a secondary fault. The main fault dips toward the southeast, with the depth of its upper breakpoint increasing from 15 m in the southwest to 40 m in the northeast. Observations also show a displacement of 8?20 m at the bottom boundary of the Upper Pleistocene. As this age represents the youngest faulted strata, the occurrence of the latest activity of the Huliuhe fault is attributed to the Late Pleistocene. This study also collected and analyzed data from magnetotelluric sounding, deep seismic wide-angle reflection/refraction, and seismic tomography profiles across the Yuguang Basin to provide a structural framework. The structural interpretation of the tomography profiles offered insights into the deep characteristics of the Huliuhe fault: the fault intersects the southern margin fault of the Yuguang Basin at a depth of approximately 10 km. Comprehensive analyses of historical earthquakes, relocated current earthquakes, focal mechanism solutions of small-to-moderate earthquakes, focal depth distribution, and the deep structure of the fault confirm that the Huliuhe fault exhibits a seismogenic structure. Earthquakes occurring near this fault are likely due to the combined activity of the Huliuhe fault and the southern margin fault of the Yuguang Basin.

• Seismic damage characteristics and cause analysis of buildings in the Diebu M_S5.5 earthquake, Gansu Province, on January 26, 2026

  ZHOU Tingru, WANG Yan, ZHONG Xiumei, WANG Qian, NI Junpeng, XU Shiyang

  2026,48(5):1210-1217, DOI: 10.20000/j.1000-0844.20260206001

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  On January 26, 2026, an M_S5.5 earthquake struck Diebu County, Gannan Tibetan Autonomous Prefecture, Gansu Province, with a focal depth of 10 km and an epicentral intensity of Ⅶ degree. It caused varying degrees of damage to buildings in the affected area. Based on post-earthquake damage assessments, this study analyzes the construction characteristics of local buildings and the seismic damage patterns across different structural types, revealing their failure mechanisms. The results indicate that rural buildings in the affected area are predominantly traditional timber-frame houses. The load-bearing timber frames mostly remained intact, but the rammed earth walls suffered severe damage, mainly cracking, partial collapse, and out-of-plane tilting. Brick-wood and brick-concrete structures are less common and primarily experienced varying degrees of wall cracking. Urban buildings are mostly brick-concrete or frame structures, with relatively minor damage, mostly wall cracking. The main causes of damage include high wall brittleness, weak connections between components, poor site selection, and unreasonable building layouts. Furthermore, most rural self-built houses lack seismic reinforcement measures. These findings can provide valuable references for post-earthquake reconstruction and seismic retrofitting of buildings, contributing to improving the overall disaster resilience of buildings in Northwest China.

• Historical remote sensing for analyzing the high-resolution geometric configuration of the northern segment of the Xiaojiang fault

  LI Xing'ao, HE Zhongtai, GUO Long, LI Linlin

  2026,48(5):1218-1227, DOI: 10.20000/j.1000-0844.20250211001

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  Abstract:

  The geometric distribution of active faults serves as a critical foundation for assessing their potential seismic hazards. Since the last century, numerous instantaneous image data have been pre-served and declassified from historical aerial photographs and KeyHole satellite imagery, providing accurate data support for assessing geological structures, tectonic landforms, and geomorphic evolu-tion processes associated with active faults. Here, two types of historical images covering the northern segment of the Xiaojiang fault were processed, and a comprehensive image processing workflow com-prising image mosaicking, registration, and geometric correction was developed. By interpreting the microgeomorphic features of the active fault from historical remote sensing images, the high-resolution geometric distribution of the fault was delineated. By integrating remote sensing interpreta-tion with field geological investigations, the geometric configuration and microgeomorphic deforma-tion characteristics of the northern segment of the Xiaojiang fault were systematically analyzed. Results indicated that this segment consisted of subparallel fault strands spaced 2—4 km apart. These strands extended along the Jinsha River and Xiaojiang River valleys, forming linear gullies. Within these linear gullies, numerous features indicative of left-lateral displacement or deflected drainage sys-tems were observed. Moreover, these faults facilitated the development of intermountain basins, form-ing intermountain basins or erosional surfaces along the mountain front. Tectonic landforms, such as fault scarps and pull-apart basins, were also developed, revealing the complex fault activity involving horizontal strike-slip and vertical movements.

• Activity of the southern segment of the Miaoshan piedmont fault in the forward area of the Tianjingshan fault zone

  DUAN Linlin, LIU lei, ZHAO Dejun, XU Yiwu

  2026,48(5):1228-1239, DOI: 10.20000/j.1000-0844.20250606001

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  In the forward area of the Tianjingshan fault zone, a well-defined Miaoshan fault-fold belt has developed, comprising reverse strike-slip faults and associated folds. The Miaoshan piedmont fault, a key structural component within this belt, remains poorly understood in terms of its detailed architecture and Quaternary deformation history in its southern segment. Shallow seismic profiling reveals that the fault displaces the subsurface reflection horizons T₁ and T₂, confirming it as a SW-dipping listric reverse fault. High-resolution remote sensing analysis indicates a lack of distinct linear geomorphic features along the fault trace, with extensive loess cover obscuring surface features—evidence consistent with limited neotectonic activity. Field geological investigations, combined with optically stimulated luminescence dating, demonstrate that older strata have been thrust over the upper Late Pleistocene deposits. Integrated analysis thus indicates that the southern Miaoshan piedmont fault is a NW-SE-striking, SW-dipping reverse strike-slip fault with a listric geometry that flattens with depth. The most recent tectonic activity of this fault is constrained to the late Late Pleistocene. This structure likely formed due to tectonic strain transfer associated with the eastward expansion of the Xiangshan—Tianjingshan fault system. Furthermore, it has not been active since the late Late Pleistocene, indicating a low potential for generating moderate-to-strong earthquakes in the future.

• A mobile phone positioning method for post-earthquake buried personnel based on PRGO-optimized multi-model fusion ranging

  WANG Guozhi, XIAO Dongsheng

  2026,48(5):1240-1250, DOI: 10.20000/j.1000-0844.20250428002

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  Abstract:

  To address the problems of low accuracy and poor stability in locating buried personnel in complex post-earthquake environments, this study proposes a post-earthquake received signal strength indication (RSSI) positioning method based on multi-model fusion ranging, which enables indirect localization of buried personnel by using mobile phone signals of trapped individuals. First, a weighted hybrid filtering algorithm is applied to preprocess RSSI data, effectively reducing noise interference in the complex post-earthquake environment. Second, the plant root growth optimization (PRGO) algorithm is used to optimize the hyperparameters of support vector regression (SVR) and radial basis function (RBF) neural networks. An ensemble ranging model integrating Polynomial-SVR, RBF-SVR, and RBF neural networks is constructed, and a fusion strategy weighted by information entropy and accuracy is adopted to improve ranging accuracy and generalization capability. Meanwhile, a minimum area weighted centroid (MAWC) localization algorithm is developed, which dynamically selects the optimal positioning polygon and iteratively approximates the true target coordinates through weighted centroid optimization. Experimental results show that after the improved filtering, the signal curve smoothness is significantly enhanced; the ensemble ranging model improves ranging accuracy by 41.67%, 29.54%, and 23.64% compared with three single models, respectively; compared with the traditional centroid localization algorithm, the proposed algorithm reduces positioning error by 0.31 m, with a final positioning error of only 0.42 m, demonstrating excellent positioning performance. This study provides reliable technical support for emergency search and rescue of buried personnel after earthquakes.

• Seismic performance analyses and improvement of existing RC multi-column bridge bents with low reinforcement ratios

  CHEN Hong, XIANG Yishuai, WANG Jing

  DOI: 10.20000/j.1000-0844.20250919001

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  This study focuses on retrofitting existing reinforced concrete (RC) multi-column bridge bents with low reinforcement ratios by installing buckling-restrained braces (BRBs) to improve seismic performance. Pushover analysis was employed to verify the accuracy of the theoretical solutions for the key performance parameters of BRBs. The seismic performance, including strength and energy dissipation, of both the original and BRB-retrofitted bridge bents was compared. Nonlinear dynamic analysis was employed to examine the displacement and curvature responses of both bridge bents under E1 and E2 seismic waves. Results indicated that the numerical seismic performance of existing multi-column bridge bents closely matches the theoretical solutions. For BRBs, the most significant discrepancies between the numerical and theoretical yield displacement, strength, and stiffness are 10.7%, 11.2%, and 5.5%, respectively. The positive and negative peak strengths and the maximum energy dissipation of the BRB-retrofitted bridge bents increased by 106.4%, 105.9%, and 214.5%, respectively, compared to the original bridge bents. This indicates that BRBs significantly improve the strength and energy dissipation of the bridge bents. Compared to the original bridge bents, the BRB-retrofitted bridge bents showed significant reductions in maximum displacement and curvature responses under E1 seismic waves (76.7% and 77.2%) and even more under E2 seismic waves (78.0% and 82.6%). Additionally, the BRB-retrofitted bridge bents remain elastic under E2 seismic waves, meeting seismic retrofitting design requirements. Therefore, retrofitting with BRBs effectively improves the seismic performance of existing multi-column bridge bents with low reinforcement ratios.

• Study on vertical vibration characteristics of marine pile considering three-dimensional effect of the pile

  Hongyou Li, Xiang Luo, Yu Wang, Quanzhi Zhou, Shugang Cao, Wei Liu, Yongshan Song

  DOI: 10.20000/j.1000-0844.20250530002

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  Considering the three-dimensional effect of the pile and the interaction of the pile, seawater and seabed, a theoretical model is developed to investigate the dynamic response of the monopile embedded in viscoelastic ground under vertical load. The pile is simplified as a three-dimensional axisymmetric homogeneous elastic medium, and its governing equation is established. The seawater is assumed to be an inviscid compressible fluid, while the seabed is regarded as a viscoelastic medium, and their governing equations are constructed respectively. Then, the variable separation method is used to solve the governing equations, and the analytical solutions for the dynamic response of the pile are obtained by combining the boundary conditions of the pile, seawater and seabed. By comparing with the degenerated one-dimensional pile-soil interaction model and the pile-water-soil finite element model, the correctness of the model in this paper is verified. Compared with the one-dimensional model, the results show that the three-dimensional pile can more accurately reflect the interaction between the pile, seawater and seabed, revealing a more complex wave propagation mechanism. For a large-diameter pile under vertical load, the traditional one-dimensional pile model would overestimate the peak velocity of the reflected wave at the pile top due to neglecting the pressure and radiation damping of seawater and seabed.

• Experimental study on the failure mechanism of heavy rainfall and shear characteristics of slip zone in Zhouqu accumulation landslide

  yangxiaohui, yanghui, guonan, zhupeng, duyibo

  DOI: 10.20000/j.1000-0844.20250322002

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  Accumulation landslides in the Zhouqu area are widely distributed and seriously harmful. To investigate?the?failure mechanism of?accumulative landslides and the shear characteristics of slip zones in the Zhouqu area under heavy rainfall, we conducted rainfall-simulation physical modeling and direct shear tests on slip zone specimens, taking the Jiangdingya landslide as a case study. The results indicate that: (1) Under heavy rainfall, the failure of the landslide mainly goes through three stages: slope surface erosion and local damage, saturation and deformation penetration of the slip zone, and overall instability. The failure mode is dominated by erosion-induced block sliding, accompanied by well-developed gullies on the slope surface and severe localized damage at the slope toe; (2) During the heavy rainfall, the accumulation landslides experienced three stages: short-term acceleration, short-term deceleration, and low-speed deformation. In the early stage of heavy rainfall, the landslide experiences traction-shear failure, in the middle and late stage of heavy rainfall, the landslide was mainly affected by the front traction; (3) In the natural state, the failure mode of the slip zone is closely related to the normal stress. The shallow slip zone shows strain softening characteristics, and the deep slip zone shows weak strain hardening characteristics; (4) Under the action of rainfall, the shear strength of the slip zone is affected by water content and normal stress, and its strength deterioration is mainly dominated by the weakening of friction characteristics between particles; (5) The failure chain of accumulated landslides under heavy rainfall can be summarized as: slope surface runoff scouring → leading edge collapse → leading edge traction and trailing edge sliding → rainwater dominant infiltration → slip zone strength attenuation → trailing edge sliding recession → main sliding surface penetration→ leading edge traction leading to overall sliding. The research results can provide a reference for the engineering prevention and control of accumulated mass landslides under heavy rainfall.

• Research on the Seismic Vulnerability of Walls Reinforced with New Rural Composite Materials

  LAI Zhenyu, WAN Huan

  DOI: 10.20000/j.1000-0844.20250512001

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  In rural brick masonry structures, the connections between walls and structural elements such as tie columns and ring beams are often insufficiently robust. Under seismic ground motions with varying directional ratios, these connections tend to become weak points, leading to overall structural failure. To address this issue, this study focuses on rural brick masonry structures, determines their foundational parameters, and employs a novel composite material, CFRP (Carbon Fiber Reinforced Polymer), for reinforcement to enhance their seismic resilience. Using the ABAQUS finite element software, a brick masonry structure commonly used in rural housing construction is modeled, and four types of seismic waves with different peak ground accelerations (PGA) are input. The DYNAMO software is utilized to achieve visual collapse warnings for the brick masonry structure under various seismic conditions in rural buildings. The results indicate that as the energy of the seismic waves decreases, the maximum stress in the CFRP-reinforced brick masonry gradually diminishes, demonstrating its effectiveness in absorbing seismic energy. This significantly enhances the seismic performance of the walls and reduces the vulnerability of rural walls under seismic action.

• STUDY ON RECOMMENDED DESIGN PARAMETERS FOR MODULAR METAL SEISMIC ISOLATION BEARINGS

  Yang Duyou, Li Jichao, Zhang Yi, Liu Jian, Deng Qingmeng, Wang Tao

  DOI: 10.20000/j.1000-0844.20250703001

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  Existing studies on seismic isolation bearings for cultural relics are mostly targeted at individual objects and lack standardized designs, limiting their direct applicability in engineering practice. This study investigates recommended design parameters for modular metal seismic isolation bearings (MMSIBs). A bilinear hysteretic model for MMSIBs is derived based on the mechanical parameters of their components, including springs, sliders, and friction dampers. A simplified model of the cultural relic–MMSIB system is established in ABAQUS. Using design goals (DGs) of an acceleration reduction ratio (ARR) not exceeding 50% and a maximum deformation (MD) not exceeding 200 mm, an illustrative dynamic time–history response analysis of a 500-kg cultural relic is carried out using 35 sets of ground motions. The influence of spring stiffness and friction damping force on the ARR, MD, and residual deformation (RD) of MMSIBs is examined. Under an additional constraint on RD (200 mm ± 1 mm), the matching relationship between the spring stiffness and friction damping force, defined as the boundary design curve (BDC), is provided for cultural relics weighing from 200 to 1500 kg. A parameter selection process suitable for engineering applications is proposed, enabling rapid identification of feasible parameter combinations according to the DGs. The results show that spring stiffness has a significant effect on ARR and RD; higher stiffness leads to higher ARR and smaller RD. Friction damping force is the key parameter controlling MD, with larger values resulting in smaller MD. The BDCs for different isolation masses exhibit a "contour line" distribution, shifting upward as the isolation mass increases. Because ARR, MD, and RD cannot be optimized simultaneously, a trade-off is required. The study provides a reliable tool for the rapid and scientific selection of MMSIB design parameters, addressing the long-standing issue of "one design for one object" in traditional bearings and providing a standardized solution for the seismic protection of museum collections.

• LA-YOLO11： a high-precision transmission tower detection algorithm combined with knowledge distillation

  LIU Rong, DOU Aixia

  DOI: 10.20000/j.1000-0844.20250702002

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  To address the challenges of complex backgrounds, occluded targets and blurred images in the transmission tower detection based on remote sensing imagery, a high-precision transmission tower detection algorithm LA-YOLO11 based on YOLO11 and augmented with knowledge distillation strategy is proposed. Firstly, a Mamba-Inspired linear attention module is integrated into the backbone network to enhance the global feature representation, improving robustness to occluded and blurred targets. Secondly, the detection head is optimized with a Minimum Point Distance-IoU (MPDIoU) regression loss, which increases sensitivity to the spatial deviations among adjacent objects and strengthens generalization ability in complex scenarios. Furthermore, the masked generative distillation strategy is applied to significantly boost the detection accuracy without introducing additional parameters and computational overhead. Extensive experiments on a high-quality satellite image dataset of transmission tower demonstrate the proposed method achieves a 1.8% improvement in mAP@50 and a 4.7% improvement in mAP@50:95 over the baseline algorithm. The comparative experimental results with the classical algorithms confirm that the improved algorithm delivers more accurate and reliable performance across challenging conditions such as complex backgrounds, occluded targets, and blurred images.

• Advances in Progressive Collapse Resistance of Spatial Structures

  XU Youxing, LV Hui, XIE Xin, LI Xianze

  DOI: 10.20000/j.1000-0844.20260113001

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  Addressing the core issue of resisting progressive collapse in long-span spatial structures, this paper reviews the definition of progressive collapse and examines typical accident cases. It clarifies the evolution of analytical methods for resisting progressive collapse, from static analysis to refined non-linear dynamic analysis, and compares the applicability and limitations of the tie-force method, the component-removal method and the critical-member method. Building on this foundation, the paper focuses on analysing the failure mechanisms, patterns for identifying critical members, and performance evaluation systems for five typical spatial structures: space trusses, reticulated shells, cable domes, suspen-domes, and beam string structures. It summarises the collapse resistance performance and optimisation strategies of each system under multi-hazard coupled conditions, and compares the core differences among the five systems in terms of redundancy, sensitivity to prestress loss, and the maturity of analytical methods. Finally, the paper highlights current research gaps and outlines future directions: there is a need to refine design parameters tailored to spatial structures, deepen research into the collaborative mechanisms of hybrid structural systems, develop a ‘structure-bracing-envelope’ collaborative model, and establish a comprehensive, multi-dimensional evaluation system for collapse resistance.

• Multi-dimensional assessment of fire resilience for metro sta⁃ tions under earthquake-induced secondary fires

  Meiling Zou, Hailing Li, Xiangcen Pan

  DOI: 10.20000/j.1000-0844.20250930002

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  To enhance the resilience of metro stations against earthquake-induced secondary fires, a multidimensional quantitative assessment framework grounded in national standards is developed. By systematically deconstructing five national fire safety codes—including the Standard for Fire Protection Design of Metro (GB 51298-2018)—a comprehensive evaluation system comprising 9 dimensions and 22 indicators is established, thereby translating prescriptive code requirements into measurable resilience metrics. To address the inherent fuzziness and randomness in the assessment process, a forward cloud model is employed to enable robust conversion of qualitative concepts into quantitative values. The proposed approach is validated through a case study of Chengdu"s Xingfu Meilin Station—the largest column-free arched metro station in China—whose fire resilience is assessed as "high" .Results demonstrate that the framework effectively transcends the limitations of conventional compliance-based inspections, offering a scientific and practical tool for quantifying and enhancing fire resilience in metro stations under compound seismic–fire hazards.

• Landslide susceptibility assessment based on fusion sampling algorithm and ensemble machine learning

  Li Limin, Zhang Bihan, Chen Feiyang, Gao Chen, Shui Haiyang, Yu Bing

  DOI: 10.20000/j.1000-0844.20250826001

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  [Objective] Landslide susceptibility evaluation is important for landslide risk prediction, but the problems of single model and sample imbalance often affect the model accuracy. [Methods] To address this problem, the study takes Shanyang County in Shaanxi Province as an example, selects 12 evaluation factors such as elevation and slope, screens the data by Pearson correlation analysis, and uses SMOTE method to interpolate and expand the positive samples, then combines with the Tomek algorithm to remove the noisy data and optimise the dataset. In order to improve the prediction accuracy, the balanced samples were classified based on RF, SVM and LR models, weighted and fused according to the AUC value, and the SMOTE-Tomek-RF-SVM-LR integrated model was constructed. [Results] Through comparative experiments, the accuracy of this model is verified to be significantly better than that of the single model and the unoptimised integrated model: 1.9% improvement over RF-SVM-LR, and 5.4%, 6.6% and 7.3% improvement over the single model RF, SVM and LR respectively. [Conclusion] The ROC curve analysis shows that the method effectively solves the sample imbalance problem, improves the prediction reliability, and can provide a more accurate reference for landslide early warning.

• Seismic ground motion input for the fault-adjacent railway station building considering the worst-case earthquake scenario

  WANG Junjie, WANG Hongwei, QIANG Shengyin, REN Yefei, WEN Ruizhi

  DOI: 10.20000/j.1000-0844.20250303001

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  To address the challenge of seismic ground motion inputs for seismic design of major railway transportation hubs in Southwest China, this study proposed a systematic method for constructing seismic ground motion inputs for near-fault railway station buildings considering the most hazardous scenario, based on the kinematic source rupture models stochastically generated and the three-dimensional seismic ground motion simulation approach. Taking the high-seismic-risk southeastern segment of the Xianshuihe fault zone in the Sichuan-Yunnan region as an example, we defined the most hazardous scenario and established stochastic rupture models for different fault segments with varying hypocenter locations. We simulated three-component acceleration time histories for the railway station building and sites adjacent to faults, and assessed the seismic impact field using instrumental seismic intensity metrics. We validated the near-fault characteristics of the simulated records from some aspects: the spatial distribution of velocity pulse characteristics caused by rupture directionality effects, the attenuation discrepancies of peak ground motion between the hanging wall and the footwall, and the uncertainty of near-fault peak ground motion caused by the stochasticity of rupture process. The most unfavorable seismic ground motion input for the station site was selected following the principle of the most unfavorable selection for near-field earthquakes, which can guarantee the representativeness of the selected seismic input. This study can offer a reliable approach to obtain the most unfavorable seismic ground motion input for the seismic design of critical transportation buildings in fault-adjacent regions.

• Stratified prediction of building seismic damage using D-S evidence theory

  lizhao, wangxumeng, hanmin, liyaoyao, luxiangyang, zhangfeng

  DOI: 10.20000/j.1000-0844.20250429002

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  To address the challenges of high uncertainty in sample data and limited prediction accuracy in the field of seismic damage prediction of buildings, this study proposes a multi-model fusion method based on Dempster-Shafer (D-S) evidence theory for stratified prediction. First, a seismic damage database was established, and six machine learning models—Random Forest (RF), eXtreme Gradient Boosting (XGBoost), Light Gradient Boosting Machine (LightGBM), Self-Attention and Intersample Attention Transformer (SAINT), Tabular Network (TabNet), and Tabular Transformer (TabTransformer)—were optimized for training. Submodels were selected through performance comparisons and heterogeneous combination strategies. Second, based on the characteristics of the submodels, a modified probability distribution function was constructed. D-S evidence theory was applied to calculate conflict coefficients and confidence interval widths, converting the uncertainty of sample data into quantifiable decision risk values. Differentiated fusion strategies were implemented based on risk levels. Finally, the proposed method was validated using the 2015 Nepal earthquake database, which includes 762,106 building samples. The results show that in the unstratified prediction scenario, the overall prediction accuracy of the sample is 53.70%, an improvement of 2.21% over the optimal single model XGBoost. In the stratified prediction scenario, the prediction accuracy of the deterministic and uncertain samples increases to 67.91% and 56.41%, respectively, representing relative increases of 29.25% and 7.35% compared to the optimal single model accuracy. The example verifies the effectiveness of this method in quantifying data uncertainty and improving prediction accuracy and decision reliability.

• Experimental Study on Seismic Dynamic Response and Deformation of Loess-Mudstone Slopes Cross-Cut by Surface Faults

  RAN Jun¹, WANG Tao², WANG Lei¹, WANG Haojie², TAI Daping², XU Xiao¹, LIU Shuai²

  DOI: 10.20000/j.1000-0844.20260120001

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  To reveal the impact of faults on the seismic dynamic response of loess slopes, a generalized loess-mudstone slope model bisected by a 70° dip-angle surface fault was designed, based on field investigations of fault-controlled slope disasters in southeastern Gansu. A shaking table model test at a 1:20 scale was conducted. The results indicate that the amplification factor of peak ground acceleration (AFPGA) exhibits a prominent "elevation effect" along the vertical direction of the slope surface, the weathering crust, and the interior slope body. The vertical acceleration amplification shows a "dual-group differentiation" pattern, which is closely related to the nonlinear damage characteristics of the slope. At the same elevation, the AFPGA of the hanging wall at the slope shoulder exceeds that of the footwall, demonstrating a significant hanging-wall effect. Furthermore, the AFPGA within the fault zone at the convex parts of the weathering crust is higher than in either the hanging or footwall, suggesting a more pronounced amplification within the fault zone itself. The deformation and failure process involves the initial formation and expansion of tensile cracks along the fault zone, followed by slight bulging at the slope toe, and ultimately the formation of a potential slip surface extending from the crest rear to the mid-slope. Notably, the scale and frequency of cracks in the hanging wall are significantly greater than those in the footwall. These findings enrich the understanding of seismic responses in faulted slopes and provide a scientific basis for seismic stability assessment and hazard mitigation.

• Analysis of Earthquake Damages of the Earthquakes with Magnitudes 4.8 and 4.6 in Yinchuan Based on Earthquake Disaster Simulation and Field Investigation

  yusihan, Lin Xuchuan

  DOI: 10.20000/j.1000-0844.20250414001

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  On January 2, 2025, two earthquakes of magnitude 4.8 and 4.6 occurred successively in Yongning County and Jinfeng District, located in the central part of the Yinchuan Fault Basin in Ningxia, causing significant social and economic impacts. To quickly obtain the seismic damage from these two earthquakes and further carry out subsequent seismic fortification work in the region, this paper realizes the simulation and analysis of seismic damage to building clusters in key earthquake-affected areas using the nonlinear elastoplastic time-history analysis method, based on the construction of refined ground motion models, geological models, and three-dimensional building models.The results show that building damage is relatively concentrated in the area within 5km of the epicenter, mainly manifested as minor damage caused by insufficient seismic resistance capacity of old buildings and self-built houses. The maximum intensity at the epicenter is VI degree, with no moderate or more severe damage observed. The seismic damage simulation results further reveal the amplification effect of the basin"s sedimentary layers on ground motion and their impact on people"s psychology.The results of this paper can provide important references for improving the seismic resilience and disaster response capabilities of cities with a large stock of old buildings, as well as for emergency response and risk prevention and control of urban direct earthquakes.

• Research on Improving Mechanical Properties and Water Stability of Loess using Super-hydrophobic Materials

  xuhong, xulei, chenwei, yuhongbao, CHENXIQI, chenjunli, yangqinqin, fanwenxiao

  DOI: 10.20000/j.1000-0844.20241219001

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  To effectively enhance the engineering properties of loess, the soil was modified by incorporating varying amounts of a superhydrophobic material, CN. A series of experiments, including unconfined compressive strength tests , soil-water contact angle measurements, and water droplet infiltration tests, were conducted. Microstructural analysis was performed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results demonstrate that the addition of CN significantly improved both the mechanical and hydrophobic properties of the loess. Specifically, with a 2% CN incorporation, the unconfined compressive strength of the loess increased from 0.64 MPa to 1.06 MPa. However, the rate of strength enhancement initially increased and then decreased with further increases in CN content. After the addition of CN, the loess exhibited no peeling after being immersed in static water for 7 days, indicating a significant improvement in its resistance to disintegration and water stability. The incorporation of CN reduced the surface free energy of the loess, increased the soil-water contact angle. With an 8% CN addition, the fractal dimension of the pore unit morphology distribution decreased from 3.118 to 1.930, reflecting a reduction in the number and complexity of pores, which resulted in a more compact and stable internal structure. The superhydrophobic material CN can effectively enhance the mechanical properties and water stability of loess. This study provides a theoretical foundation for the practical application of modified loess.

• Study on the Evolution Mechanisms of Inflection Points in High-Rise Steel Frame Structures Based on Hybrid Test Boundary Conditions

  fuzhuyi, tianshizhu

  DOI: 10.20000/j.1000-0844.20250409002

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  This study investigates the dynamic evolution of inflection point positions in high-rise steel frame structures during strong nonlinear phases under shaking table substructure hybrid tests, focusing on the complexity of boundary condition simulations based on the inflection point method. By establishing a finite element model of a steel frame structure derived from the SAC-Benchmark model and employing kernel density estimation (KDE), the influence mechanisms of seismic parameters—including peak ground acceleration (PGA), waveform characteristics, and time-domain loading history—on the height ratio of inflection points in frame columns are systematically analyzed. The results demonstrate that as seismic intensity increases, the inflection point height of corner columns in lower floors exhibits a significant upward migration trend, whereas mid-to-high-rise columns show minimal displacement consistent with code-predicted patterns. Distinct waveform characteristics differentially affect inflection point distributions, with short-duration strong-motion waves exacerbating data dispersion and inducing positional fluctuations. High-frequency pulse components during time-domain loading markedly alter the concentration characteristics of inflection points, leading to multimodal distribution phenomena. This study elucidates the dynamic migration patterns of inflection points in structural nonlinear phases under intense seismic actions, providing a theoretical foundation for simplifying boundary conditions in shaking table hybrid tests through inflection point-based methods, thereby substantially reducing the system"s demand for complex boundary control.

• Analysis of Ground-Motion Characteristics of the Feidong, Anhui Ms4.7 Earthquake and Estimation of Damage Potential from High-Potential Magnitude Earthquake

  zhangrunkun, zhangyan, lixi, lizongchao, baoziwen, wangxiaoli, liuyijun

  DOI: 10.20000/j.1000-0844.20260207001

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  On September 18, 2024, an MS 4.7 earthquake struck Feidong County, Anhui Province, China, and caused considerable public concern. This study uses ground-motion records from 135 seismic stations of different types located near the epicenter. It systematically examines the acceleration time histories and response spectra, ground-motion attenuation, spatial distribution of shaking, and site amplification effects of this event. The MS 4.7 earthquake was further treated as a small-event Green’s function. Uncertainties in source parameters were also taken into account. Based on the empirical Green’s function method, the potential damage caused by a scenario MS 6.0 earthquake in this region was simulated and evaluated. The implications of larger potential earthquakes for regional seismic safety were then discussed. The results show that: (1) ground-motion amplitudes recorded by different types of stations differ significantly. Under similar location conditions, the peak PGA and PGV recorded by strong-motion stations are 63.2 and 11.4 times those recorded by regular seismic stations, respectively. This finding indicates that the thick sedimentary cover in the study area substantially amplifies the damaging potential of ground motion, especially at a period of 0.1 s; (2) the attenuation patterns of ground motion also vary markedly among different station types. The attenuation rate observed at intensity stations is clearly higher than that at strong-motion stations and regular seismic stations; (3) this MS4.7 earthquake, which occurred in an area with thick sedimentary cover, was a relatively destructive event among earthquakes of comparable magnitude; and (4) for the MS 6.0 scenario earthquake, the PGA may reach 0.8~1.0g at some locations, corresponding to a seismic intensity of up to X. This study suggests that special attention should be paid to the significant amplification effect of thick sedimentary cover on ground motions at specific periods. The potential impact of future larger-magnitude earthquakes on the structural safety of super high-rise buildings in this region should also be evaluated.

• Seismic structural response prediction based on multiscale hybrid Kolmogorov-Arnold networks

  guomaozu, cuizheng, zhaolingling, zhangqingyu

  DOI: 10.20000/j.1000-0844.20241220003

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  Accurately predicting structural response under seismic loads is critical for assessing structural damage and performance. Addressing limitations in the predictive capability and efficiency of current seismic response prediction methods for long time series data, as well as considering the scarcity of seismic data, this study adopts a novel neural network model that combines the Kolmogorov-Arnold neural network and gated recurrent unit, along with a multiscale hybrid method. This approach effectively enables real-time prediction of multi-degree-of-freedom response time histories in building structures under conditions of limited seismic data. To verify the accuracy and efficiency of the proposed method, four case studies were conducted on publicly available datasets. Additionally, ablation and comparative experiments were performed to further evaluate the feasibility of the model. Results demonstrate that the proposed method accurately predicts acceleration, velocity, and displacement time histories across multiple degrees of freedom within the structure, surpassing the prediction accuracy of existing models, such as the Long Short-Term Memory (LSTM-f) network and Convolutional Neural Network-Long Short-Term Memory (CNN-LSTM) model. This model achieves efficient, accurate predictions even with highly limited training data, fulfilling the requirements for practical engineering applications.

• Seismic Performance Experimental Study on Vertical Connection Joints of Modular Concrete Wall-Floor

  Huanglei, Du Junzi, Lida, Wang Zelong, Xie Xiaomeng, Lijie

  DOI: 10.20000/j.1000-0844.20241211001

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  Abstract:

  To explore the seismic performance of vertical connection joints in modular concrete wall-floor, this study designed and tested three types of joints: monolithic casting, grout anchor connections, and bolt connections under cyclic loading. The research systematically evaluated their failure processes, hysteresis behavior, energy dissipation capacity, and the degradation of stiffness and strength. The test results indicate that regardless of the connection type used, all specimens tended to fail through bending and demonstrated excellent seismic performance, meeting the seismic demands in practical engineering applications. The seismic performance of the vertical connection joints using grout anchor connections was nearly identical to that of the monolithic cast specimens, showing comparable strength, ductility, energy dissipation capacity, and stiffness. However, specimens with bolt connections had lower strength and stiffness than monolithic cast specimens, but exhibited better ductility and enhanced energy dissipation performance compared to those using grout anchor connections and monolithic casting.

• Seismic vulnerability analysis of jacket offshore platform considering SSI effects

  LIU SHUTONG, TANG SONG, LI HAOCHEN, YANG SHUTONG, LI PEIZHEN

  DOI: 10.20000/j.1000-0844.20250306001

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  Abstract:

  Based on the vulnerability analysis method, this study adopts a typical jacket offshore platform in the Bohai Sea region as an engineering case. This study investigates the seismic vulnerability of the platform under combined earthquake and wave loads, specifically exploring the influence of soil-structure interaction (SSI). To conduct the seismic vulnerability analysis of the jacket offshore platform considering SSI effects under wave and earthquake excitations, the finite element model is established by OpenSees software, and the incremental dynamic analysis method is adopted, using the inter-story drift as the damage indicator. The results demonstrate that for the vulnerability curves corresponding to a particular state, the rate of increase in structural damage probability initially rises and subsequently declines with increasing peak ground acceleration, and the damage risk of jacket offshore platform caused by near-field earthquake is higher than that of far-field earthquake case. In addition, compared to jacket offshore platform considering SSI, the equivalent pile model reaches limit states more readily under combined earthquake and wave loading, with lower safety margins, suggesting the mitigating effects of soil.

• Accuracy evaluation of post-seismic rapid assessment influence field

  Zhang Meng, Wen Xintao, Li Jinxiang, Wang Keifeng

  DOI: 10.20000/j.1000-0844.20250122002

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  Abstract:

  Earthquake emergency rapid assessment product is an important support for post-earthquake emergency command work, and the accurate and reliable rapid assessment impact field is the foundation of emergency products. To evaluate the application effect of post-earthquake rapid assessment impact field, this paper took 94 destructive earthquakes from 2001 to 2024 as the research objects, and studied the deviations and causes between the surveyed intensity circles and the assessed impact fields in three aspects: epicenter location, long-axis direction, and attenuation relationship. The results showed that:(1) The deviation between the macro epicenter and micro epicenter was mostly within 5 km, but factors such as the superposition of earthquake damage, house distribution, co-seismic geological disasters, and surface rupture would expand the deviation;(2) The use of fault information to assess the long axis direction could meet the application needs for most earthquakes, while factors such as the absence or misjudgment of the seismiotectonics the inconsistency between residential areas and the fault direction would increase the deviation;(3) The attenuation model could reflect the intensity attenuation process of the long and short axis directions of most earthquakes, but the surveyed intensity circles were affected by terrain and the distribution of residential areas; such models were not applicable to earthquake events that cause large-scale co-seismic surface rupture.

• Experimental study on the seismic performance of prefabricated concrete shear walls with grouted sleeve connections under vertical tension

  FANG Zhihao, XIONG Feng, 顾盛, 刘学春, 方有珍

  DOI: 10.20000/j.1000-0844.20250318001

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  Abstract:

  Gouting sleeve assembly connection is one of primary connections of prefabricated concrete shear wall structures, but its seismic mechanism is currently unclear due to lack of research on its seismic performance under vertical tension result from violent earthquake and hurricanes. To systematically study seismic mechanism of prefabricated concrete shear wall with grouting sleeve assembly connection, tests of 2 full-scale specimens as conventional reinforced cast-in-situ shear wall XSW, prefabricated concrete shear wall with grouting sleeve assembly connection TSW were conducted under lateral cyclic load with constant vertical tension. Based on test phenomena and data, hysteretic characters, stiffness, energy-dissipation capacity, ductility coefficient and deformation mode were analyzed to reveal its seismic mechanism. Research results showed that ultimate bearing capacity of specimen XSW and TSW have minor differences for reinforcement layout , while specimen XSW has superior deformability; developing pattern of equivalent viscous damping coefficient of two specimens were same at initial loading stage, and accumulated hysteretic energy dissipation of specimen XSW was approximately twice as TSW; deformation mode of specimens XSW was ideal inverted triangle early and obvious shear deformation latter, but specimen TSW was always inverted triangle; failure mode of specimen XSW is mainly concrete crushing in region above wall corner and crack edge concrete loosening, however specimen TSW is low cycle fatigue fracture of reinforcements at assembly connection gap with significant detachment.

• Overview of worldwide earthquake disasters in 2025

  QIAN Geng, YANG Dongyue, FENG Wei, ZANG Nan, Wang Jianwei

  DOI: 10.20000/j.1000-0844.20260226001

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  Abstract:

  To monitor global seismic disaster dynamics in a timely manner, investigate the implications of typical earthquake cases for China’s tectonic activity, accumulate experience in earthquake damage prevention, and strategize the deployment of earthquake prevention and disaster reduction initiatives, this paper compiles earthquake catalogs and disaster data since 1900, systematically clarifies global seismic activity and disaster characteristics in 2025. This study summarizes the patterns of global damaging earthquakes from 1975 to 2025, plots the spatial distribution of 2025 disaster events, and compiles detailed information on casualties. Furthermore, the study conducts historical reviews and disaster analyses of two major events to extract the core characteristics of seismic disasters in 2025. Compared with 2024, global seismicity intensified in 2025, marked by the occurrence of one magnitude 8 or greater earthquake. These events resulted in 7971 deaths and over 20000 injuries, representing a significant surge in casualties. Damaging earthquakes in 2025 were characterized by high frequency, severe casualties, frequent secondary disasters, and a linear clustering of major disasters along the Eurasian Seismic Belt. In response to the high frequency of disasters, distinct distribution patterns, and prominent causes of casualties, this paper proposes corresponding measures and suggestions for earthquake disaster prevention, emphasizing the Eurasian Seismic Belt as a priority defense zone. This study highlights the need to enhance the effectiveness of seismic technology in disaster mitigation, while underscoring that national stability serves as a robust guarantee for earthquake rescue operations.

• Two-stage emergency material scheduling optimization for earthquake disasters

  Ma Weiliang, Zhang Gang, WU Yao

  DOI: 10.20000/j.1000-0844.20250420001

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  Abstract:

  Earthquake disasters, which are highly unpredictable and destructive, often result in significant losses, making post-disaster emergency response crucial. To address the emergency material scheduling problem in earthquake disasters, a two-stage scheduling model is developed, which divides the transportation of materials into two phases: allocation and dispatch. The first phase optimizes the distribution of rescue resources, while the second phase schedules these resources to ensure timely coverage of all disaster-stricken areas. A mixed-integer programming model is developed with the objective of minimizing coverage time, integrating land-air transportation and incorporating multiple influencing factors. The optimization model is implemented and solved using Python and Gurobi. Case studies and sensitivity analyses based on the Wenchuan earthquake validate the model’s effectiveness and robustness. The model provides decision support for emergency rescue operations and proves valuable for guiding rescue command centers. Future research may explore optimizing rescue resource deployment under uncertain conditions.

• A Study of Calibration for Multi-damping ratio acceleration response spectrum of near-fault velocity pulse record

  zhang xiaonan, YUAN Xiaoxiang

  DOI: 10.20000/j.1000-0844.20250718001

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  Abstract:

  Near-fault velocity pulse ground motion records are characterized by large amplitude and long pulse period, which tend to cause significant damage to engineering structures. This study selects 107 near-fault station horizontal velocity pulse-like records of 16 seismic events. The records are classified into 6 types. The multi-damping ratio acceleration response spectra are calibrated using the differential evolution algorithm. The differences between the calibrated spectra of different types of residual records and the original records are compared. The variation trends of the calibrated spectra parameters with damping ratio are analyzed. The conclusions are as follows: In the short-period range, the calibrated spectra of the original records are similar to those of the residual records. In the long-period range, the calibrated spectra of the original records are significantly larger than those of the residual records. The average βmax and γ of different faults and velocity pulse types decrease with the increase of damping ratio. The average Tg of the calibrated spectra of the original records is greater than that of the corresponding residual records. The average βmax values of the original records and the residual records are similar. The average γ of the calibrated spectra of the residual records is greater than that of the original records.

• Vertical ground motions of seasonally frozen soil under the formation of ice lenses

  LI Qiang, CHEN Xingyu, WEN Minjie, GUAN Wenjie

  DOI: 10.20000/j.1000-0844.20250104001

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  Abstract:

  The upper active layer of seasonally frozen ground freezes in winter. During the freezing process, due to water migration, ice segregation often occurs on the freezing front, resulting in the formation of ice lenses. By using saturated frozen porous media to simulate frozen soil, saturated porous media to simulate unfrozen soil, and single-phase elastic media to simulate ice lenses, a simplified one-dimensional seismic response model of seasonally frozen soil with ice lenses was established. The Laplace transform method is used to obtain the analytical solution of the one-dimensional seismic response of the seasonally frozen soil layer in the frequency domain, and the time-history response is obtained by means of the numerical integral inverse transformation. The calculation results show that the numerical solutions agree well with the analytical solutions, and the one-dimensional seismic response of the seasonally frozen soil layer can be well degraded to that of the saturated soil layer when the temperature is close to the frozen point. The effects of the structural parameters of the layered seasonally frozen soil on the vertical seismic response are discussed. The results show that the thickness of the underlying layer, the thickness of the ice lens, the thickness of the freezing front, the temperature gradient and the ground surface temperature have significant impact on the seismic responses. Therefore, attention should be paid to the impact of the formation of ice lenses in seasonally frozen soil on the natural vibration periods and seismic responses of the site.

• Analytical study of SH wave scattering in parallel tunnels near V-shaped valley

  ke bocheng, Zhang yu, Zhang ning

  DOI: 10.20000/j.1000-0844.20250506001

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  Abstract:

  The seismic response of tunnels adjacent to valley is significantly influenced by local amplification or attenuation of ground motions. While previous studies have examined valley effects on single-lined tunnel, the theoretical understanding of SH-wave scattering in sites featuring both V-shaped valleys and multiple tunnels remains limited. This study investigates two-dimensional scattering of plane SH waves by a V-shaped valley with parallel-lined tunnels in a half-space using the wave function expansion method. Wavefields for the valley, parallel-lined tunnels, and their mirror images are established, and a system of equations is derived from stress-free boundary conditions along with stress and displacement continuity conditions to determine the unknown complex coefficients. The analysis examines how incident wave angle, dimensionless frequency, tunnel size, and spacing affect surface displacement and dynamic stress around the tunnels. The results indicate that a V-shaped valley with parallel-lined tunnels exhibits a significantly more intense ground motion than one with a single tunnel. Furthermore, increasing frequency significantly enhances topographic amplification on the valley side adjacent to the parallel tunnels. Dynamic stress concentration around the tunnels also becomes more pronounced with higher incident wave frequencies and larger tunnel dimensions.

• Evaluation of Geological Hazard Susceptibility in Huazhou District, Weinan City Based on GIS and Weighted Information Model

  LI Jian-bo, SHI Shuai, REN Dong

  DOI: 10.20000/j.1000-0844.20250707001

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  Abstract:

  Huazhou District, situated in the southwestern part of Weinan City, Shaanxi Province, is characterized by complex and diverse landforms, with widespread geological hazards that pose a severe threat to public safety and property. To improve the accuracy of regional geological hazard assessment, the adoption of scientifically rigorous modeling methodologies is crucial. This study selects eight evaluation indicators—slope gradient, slope height, aspect, mean annual precipitation, engineering geological rock-soil type, landform type, surface water basin, and distance to roads—and integrates them into a Geographic Information System (GIS) framework. The weighted information value model is employed to assess the geological hazard susceptibility of Huazhou District. The analytical results reveal that landform unit type is the dominant controlling factor governing the development of geological hazards in the region, while mean annual precipitation acts as a key triggering factor. The study area is delineated into four susceptibility zones: non-prone, low-susceptibility, moderate-susceptibility, and high-susceptibility, with corresponding areas of 276.68 km2, 478.82 km2, 294.96 km2, and 88.54 km2, respectively. The spatial point density distribution of historical hazard events exhibits a high degree of consistency with the derived susceptibility map, verifying the reliability of the model. These findings provide a robust scientific basis for the formulation of disaster prevention planning, land use management, and risk mitigation strategies in Huazhou District, Weinan City.

• Design method and performance analysis of inerter-based seismic isolation for complex structures considering soil-structure interaction

  Zhao Zhipeng, Tang Yuanchen, Zhang Bingbing, Hong Na, Chen Qingjun

  DOI: 10.20000/j.1000-0844.20250318002

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  Abstract:

  The complex structure represents a critical form for enhancing urban underground space utilization, characterized by its distinctive composite structural configuration and high-performance functional resilience requirements. There is a pressing need to advance research on seismic performance evaluation and resilience enhancement technologies. The inerter system, leveraging inertial amplification and tuning-based vibration absorption mechanisms, offers the ability to flexibly adjust inertial characteristics and control the dynamic response of the host structure. This paper proposes an inerter-based isolation system tailored for complex structures and delineates its installation methods, simulation methodologies, and parameter design procedures. Using a typical complex structure as an engineering case study, a numerical simulation analysis was conducted on the soil-inerter isolation system-complex interaction system and recommended design parameters for the inerter-based isolation system are provided. The results indicate that the design procedure of the inerter-based isolation system effectively correlates design parameters with the structural response of the complex, thereby achieving the seismic design objectives. The proposed system effectively controls acceleration, displacement, and stress responses of the complex structure. In comparison with conventional isolation schemes, it simultaneously satisfies the multi-objective coordinated control requirements of both the complex structure and the isolation layer. Moreover, while significantly mitigating the seismic response of the superstructure above the complex, the inerter-based isolation system does not adversely affect the seismic performance of the underground portion.

• Research on freeze-thaw mechanical properties and model parameters of coastal saline soil in seasonal frozen area

  Beibei, SONG Yang, SHI Xiulian, LI Yanhong, WANG Yunda

  DOI: 10.20000/j.1000-0844.20250430001

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  Abstract:

  The western coast of Bohai Bay is a typical seasonally frozen region where coastal saline soil is widely distributed. Under the influence of freeze-thaw cycles, this saline soil is prone to causing pavement distresses such as frost boiling and frost heave, thereby compromising highway serviceability. To investigate the mechanical properties of this soil, this study selected the coastal saline soil from Huanghua, Cangzhou as the research object. Subsequently, based on the Duncan-Chang model, triaxial compression tests were conducted using the LFTD1820 dynamic triaxial test system on soil specimens subjected to freeze-thaw cycles. The stress-strain relationships of the soil under different numbers of freeze-thaw cycles were analyzed, and the effect of the number of freeze-thaw cycles on the parameters of Duncan-Chang hyperbolic model was ascertained. The results indicate that the deviatoric stress-strain curves of the coastal saline soil conform to the Duncan-Chang hyperbolic model under varying numbers of freeze-thaw cycles. As the number of freeze-thaw cycles increases, the cohesion exhibits an exponential decay, while the internal friction angle generally decreases. As the number of freeze-thaw cycles increases, the Duncan–Chang parameter K decreases linearly, parameter n exhibits significant fluctuations, and the failure ratio Rf varies between 0.959–0.909. A modified Duncan-Chang model that incorporates the effects of freeze-thaw cycles is proposed, which accurately reflects the effects of confining pressure and freeze-thaw cycles on the strength and deformation of coastal saline soil.

• Research Progress of Self-Centering Dampers: From Component Mechanisms and Structural Topology to System Integration

  CHEN Chao, zhangguojun, jianghao, hanxiaoyan

  DOI: 10.20000/j.1000-0844.20260305002

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  Abstract:

  Traditional seismic design typically dissipates seismic energy through plastic deformation of the main structure. While this design concept can effectively ensure life safety, it often results in excessive residual deformation that renders buildings inoperable, leading to substantial indirect social and economic losses. To address this challenge, structural engineering is gradually shifting from the collapse?oriented design paradigm to a functional recoverable resilience?based design paradigm. As a key component for improving seismic resilience, self?centering dampers provide structures with post?earthquake self?recovery capability by integrating recentering and energy?dissipation elements. However, the complex coupling mechanism between recentering and energy?dissipating elements within a single device has become the core bottleneck for performance optimization. Base on this background, this paper breaks through conventional classification methods and innovatively proposes a classification framework based on the combination of internal functional elements. Self?centering dampers are categorized into three typical configurations: independent, parallel, and composite types. The working mechanism, performance advantages, and research progress of each configuration are systematically elaborated. The results show that the independent damper represents a straightforward implementation of self?centering technology and can serve as an idealized model for investigating material mechanisms and coupling behaviors. The parallel damper is the most applicable engineering solution due to its excellent tunability and reliable configuration. The composite damper further integrates functions on the basis of decoupled parallel dampers, which greatly expands the performance envelope and design freedom, offering an innovative solution for complex seismic design requirements.

• Research on structural influence coefficient of twisted structural system composed of the core tube and vertical staggered trusses

  zhubingyan, liqicai

  DOI: 10.20000/j.1000-0844.20250225002

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  Abstract:

  A novel twisted structural system which composed of the core tube and vertical staggered trusses is conducted in this paper. Due to the limited number of vertical components and the necessity to compensate for the reduction in the vertical load-bearing capacity caused by this twisted elevation molding, the cross-sectional dimensions of the components are designed significantly larger than conventional structures, which providing more stiffness. Although this twisted structural system has been applied in practical engineering, the corresponding studies on the structural influence coefficient R is under-researched. In this paper, 5 calculation models have been designed in accordance with the Chinese standards, with different twisting angles as variables. For each model, pushover analysis was conducted utilizing the stepwise lateral force adjustment method, with consideration given to the effects of higher-order vibration modes. The structural influence coefficient R for each model was calculated based on the improved capacity spectrum method. The study analyzed the impact of twisting angles on the structural influence coefficient and found that the structural influence coefficient R is inversely proportional to the twisting angle. It is particularly noted that the twisted structural system can use the structural influence coefficient of the 6° model, which is 4.270. This value is 15.3% higher than the recommended value for conventional frame-core tube systems" in the "General rule for performance-based seismic design of buildings." For those existing structures using traditional structural influence coefficient intended for non-twisting structural systems, the seismic actions may be overestimated, resulting in cost-ineffective designs.

• Dynamic Response Analysis of the Octagonal Steel Frame of SunYat-sen Memorial Hall in Guangzhou under Wind-Seismic Coupling

  lihao, Zhoulian, xu li, rao maosen

  DOI: 10.20000/j.1000-0844.20250305001

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  Abstract:

  The Sun Yat-sen Memorial Hall in Guangzhou, a nationally protected historic landmark with nearly a century of history, is famous for its unique architectural shape formed by a large-span octagonal steel roof truss. The dynamic performance of this steel roof system under the action of earthquakes and wind loads is critical to the structural safety of the building. To evaluate its safety under extreme loading conditions, this study investigated the structural dynamic characteristics of the steel truss system based on historical archives and 3D laser scanning data and updated an ABAQUS finite element model using results from Ambient Vibration Testing (AVT). Three ground motion records and wind loads with recurrence intervals of 10, 50, and 100 years were selected for nonlinear time-history analyses to investigate the coupled wind–earthquake response of the structure. The results indicate that, under a peak ground acceleration (PGA) of 0.4 g and a 100-year recurrence interval wind load, the maximum displacement at the roof of the steel truss system is 53.3 mm, and the maximum inter-story drift ratio is 1/125, both within the maximum displacement limit specified in the standard. Moreover, wind loads have a significant impact on structural displacement. Under the 100-year recurrence interval wind action, the root mean square (RMS) displacement reaches 13.05 mm, which is substantially higher than that caused by seismic action alone. The results demonstrate that the steel roof truss exhibits excellent wind and seismic resistance, providing critical technical support for the safety evaluation and preservation of historic buildings.

• Study on the seismic vulnerability of prefabricated prestressed utility tunnel crossing active ground fissures

  XU Qiang, WEI Leqing, HUANG Qiangbing, CAO Jianzhen, Wu Shaoyan, Tian Qinhu, Zhang Yong

  DOI: 10.20000/j.1000-0844.20251020001

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  Abstract:

  When utility tunnels traverse active faults, it is necessary to comprehensively consider the combined effects of fault interfaces and ground subsidence on their seismic performance. A quasi-static loading test was conducted to evaluate the seismic performance on active ground fissure sites of prefabricated utility tunnel. The test evaluated the failure patterns, deformation characteristics, and hysteretic response of the utility tunnel under transverse horizontal loading. Damage evaluation indices were established to quantify the performance state of the utility tunnel. While a numerical model were developed to simulate various ground fissure site scenarios, which indicated that the dynamic response of the utility tunnel is more likely to appear near the ground fissure, diminishing with distance, while the hanging wall exhibiting a more significant response than the footwall. Moreover, structural damage exacerbate with the increase of ground fissure. At a ground fissure subsidence of 250 mm, the maximum inter-story drift ratio of the utility tunnel reached 1/93, which is 3.16 times and 3.96 times greater than that of a site without subsidence and a complete site, respectively. A seismic vulnerability model for the utility tunnel was constructed using the incremental dynamic analysis (IDA) method, incorporating 16 ground motion records. This model evaluates the failure probability of the utility tunnel"s seismic performance under coupled effects of varying ground motion intensities and ground fissure subsidence. The results provide valuable insights for the seismic design and disaster mitigation of prefabricated utility tunnels in active ground fissure zones.

• STUDY OF EARTHQUAKE GROUND MOTION PARAMETERS CHARACTERISTICS OF AIRPORT HIGH-FILL SITES

  HUANG Xin, WANG Longxin, WU Kun, FENG Xing

  DOI: 10.20000/j.1000-0844.20250207002

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  Abstract:

  To enhance the seismic safety of airport engineering structures, it is important to study the effect of airport high-fill site on earthquake ground motion parameters. A three-dimensional numerical analysis model of an airport high-fill site using the time-domain analysis method is developed, and the site boundary effects is considered by using infinite elements method. Considering the influence factors such as the location of the high-fill site, the height of the high-fill site and the amplitude of the earthquake ground motion, the characteristics of the earthquake ground motion parameters of the high-fill site of the airport are analyzed by using the PGA dynamic amplification coefficient as the index. The results indicate that the earthquake ground motion effect of the high-fill site amplifies with increasing vertical height, peaking at the site surface, and its amplification effect should not be neglected. Meanwhile, the PGA dynamic amplification coefficient varies with input earthquake waves, for instance, the PGA amplification coefficients of the site surface under natural wave 1 and natural wave 2 are 2.48 and 2.05, respectively. Furthermore, high-fill sites effectively filter high-frequency components of input ground motion, with filtering intensity increasing along the vertical height, such as 46.7%, 96.1% and 97.3% of components below 2 Hz in natural wave 1 and when transmitted to the bottom and surface of the site, respectively. With the increase of high-fill height, the amplification of the PGA dynamic amplification coefficient on the surface of the high-fill site firstly increases and then decreases, such as the PGA dynamic amplification coefficients are 2.24, 2.48 and 2.29 for fill heights of 30m, 40m and 50m respectively under the natural wave 1 action. Compared with frequent earthquake and fortification earthquake, the ground motion amplification effect of the airport high -fill site under rare earthquakes is reduced.

• Influence of mountain valley topography on the seismic response of high-pier, large-span bridges

  guo kun lin, Li Xiaojun, Wang Ning, Wen Zengping, Wang Yanbin

  DOI: 10.20000/j.1000-0844.20240527001

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  Abstract:

  Seismic wave propagation in irregular terrain sites can lead to changes in the amplitude and spectral components of ground shaking on the site surface, resulting in spatial and temporal differences in ground shaking at different locations on the site surface. The oblique incidence of seismic waves will exacerbate this difference, resulting in a more complex seismic response for bridge structures on the site. By constructing the site and bridge models, and taking the bridge structural support as the observation point, we calculate and analyze the variation rule of ground vibration on the surface of the site with different incidence angles in the river valley terrain. Further take the ground vibration at the bridge piers on the site surface as the input, simulate the structural response of the bridge structure with multi-point non-uniform ground vibration input, and explore the influence of mountain valley topography on the seismic response of high pier and large-span bridges. The computational analysis shows that: (1) the incidence angle of seismic wave significantly changes the degree of influence of topographic effect on the seismic response of bridge structure; (2) the non-uniformity of ground shaking caused by topographic effect leads to the complexity of the internal force response of the bridge structure, and the maximum increase of the internal force of the bridge structure is 388% compared with the uniform excitation. It is suggested that the seismic design of bridge structures with high piers and large spans across river valleys should fully consider the influence of topographic effect on the structural response of bridges, and should pay enough attention to the influence of seismic wave incident direction and its uncertainty.

• Shaking table test of the dynamic response of geocell retaining walls

  HOU Xianming, JIN Feifei, SONG Fei, LIU Xuejun, CHEN Xin, WANG Lili

  DOI: 10.20000/j.1000-0844.20250218003

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  Abstract:

  : A large-scale shaking table model test was carried out to study the effects of ground motion parameters on the cell strain and the acceleration of the retaining wall. The results show that the cell strain and acceleration change nonlinearly along the wall height. With the increase of amplitude and frequency, the cell strain and acceleration increase gradually, and the maximum strain appears near the elevation 11/2. The increase of cell strain and acceleration is small when the frequency is 1~4Hz, and larger when the frequency is more than 4Hz. Under the three directions, the dynamic response of the retaining wall is the strongest when the action is in the XZ direction. While the time of persistence has little effect. The acceleration of column 1 is less than that of column 2, and the retaining wall of the geocellular cell has a certain attenuation effect on the seismic energy, showing good seismic performance. The research results have certain reference value for seismic design and practical application of geocell retaining wall.

• Research on the Model of Post-earthquake Casualty Transfer Based on Connected Graph and Linear Programming

  baoyintu, HAO Liang, PAN Peng-yuan, NARENMANDULA, XU Mao-chen, WANG Peng-xiang

  DOI: 10.20000/j.1000-0844.20251014003

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  Abstract:

  This study addresses the issue of casualty evacuation during earthquake disasters by constructing a casualty transfer model that integrates connected graphs and linear programming. The model first establishes the topological relationship of the road network using the Floyd algorithm, determining the shortest transfer routes from disaster areas to hospitals. Subsequently, through a linear programming approach with constraint settings, the optimal number of casualties to be transferred is determined to ensure the shortest transfer routes and minimal total time consumption. A genetic algorithm model is also developed for comparative validation. Taking a specific area in Hohhot as the research subject, this study simulates the transfer routes and numbers of severely injured casualties under the assumption of a strong earthquake occurring in the evening or at night, estimating the number of casualties and road traffic conditions through empirical formulas. The results demonstrate that the model can effectively solve for the minimum total time and shortest total routes required for casualty transfer, verifying its practical feasibility. Simulation experiments further confirm that the model significantly improves casualty evacuation efficiency, reduces rescue costs, and shortens rescue time. Additionally, the practical applicability and potential for future expansion of the model are discussed, aiming to provide a theoretical basis and practical reference for earthquake disaster emergency rescue.

• A review on structural health monitoring technology driven by the integration of digital twin and artificial intelligence

  Liu Hongbo, Pei Yuexiong, Wang Longxuan, Xu Jiakai, Li Xuanzhi, Zhang Haijiang, Chen Zhihua

  DOI: 10.20000/j.1000-0844.20250809001

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  Abstract:

  The rapid advancement of Artificial Intelligence (AI) and Digital Twin (DT) technologies has invigorated the field of Structural Health Monitoring (SHM) with novel technical dynamism. By constructing high-fidelity virtual models of physical structures, DT technology, when integrated with AI, enables real-time reflection of structural health status and predictive analytics. The deep integration of these two technologies can significantly improve the accuracy and decision-making efficiency of SHM. To systematically review the research progress and application status of integrated DT and AI technology in SHM, this paper first elaborates on the fundamental concepts of DT and AI and their application value in the field of SHM. Then comprehensively discusses the research status of SHM and early warning technology integrating DT and AI from five dimensions: Onshore Engineering Structures, Underground Engineering Structures, Highway and Bridge Structures, Offshore Engineering Structures, and Disaster Early Warning and Assessment of Engineering Structures. Finally, it summarizes the current research progress and prospects future development directions, aiming to provide a valuable reference for subsequent research and engineering practice in this fields.

• Recent Advances in the Seismic Performance of Prestressed Concrete Bridge Piers

  XU Guomin, ZHANG Xianke, HUANG He, KANG Ling, BAI Haoyuan, JIA Junfeng, TIAN Li

  DOI: 10.20000/j.1000-0844.20250827001

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  Abstract:

  Under strong seismic actions, it is essential not only to prevent the collapse of bridge structures to ensure the safety of people on the bridge, but also to pay close attention to structural damage, in order to facilitate the rapid post-earthquake recovery of traffic functionality and repair processes. Prestressed concrete bridge piers have attracted considerable attention for their advantages in seismic performance. The internal prestressing tendons can provide effective restoring forces for the piers while controlling seismic damage, thus reducing residual displacements and enhancing the rapid post-earthquake functionality recovery of the bridge to a certain extent. This paper reviews recent advances in the seismic performance of prestressed concrete bridge piers from two aspects: cast-in-place concrete piers and precast segmental piers. First, the development background of prestressed concrete bridge piers is briefly introduced, followed by a summary of research findings on cast-in-place reinforced concrete piers incorporating vertical prestressing tendons. Then, the latest research progress on precast segmental piers with prestressed connections is presented, focusing on energy dissipation mechanisms, shear resistance strategies, damage control measures at the pier base, and theoretical analysis approaches. Finally, based on the current status of theoretical research, technological development, and engineering applications both domestically and internationally, the development trends of prestressed concrete bridge piers are summarized. Research findings indicate that, compared to conventional cast-in-place reinforced concrete piers, prestressed concrete piers exhibit significantly reduced residual displacements after earthquakes. In most cases, supplemental energy dissipation devices are required to enhance energy dissipation capacity, and local damage to the piers is reduced. Prestressed connection technology shows significant advantages in constructing self-centering rocking piers and multi-segment precast piers. Future research should focus on several key areas: numerical modeling methods for prestressed piers, performance-based seismic design of self-centering piers and their engineering validation, seismic and durability performance of prestressed high piers with segmental construction, anchorage and construction techniques for prestressing tendons, and the seismic performance of pre-tensioned prestressed concrete piers.