• Volume 40,Issue 3,2018 Table of Contents
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    • >地震工程
    • Study on Time-varying Damage Model of Multi-age Steel Frame Structures

      2018, 40(3):389-397. DOI: 10.3969/j.issn.1000-0844.2018.03.389

      Abstract (802) HTML (0) PDF 9.23 M (961) Comment (0) Favorites

      Abstract:In recent years, with the improvements in steel production and processing technologies, steel structures are being widely used in large public buildings. Generally, corrosion is a major problem in the lifetime of steel structures, which leads to the thinning of the structural material, changes in its mechanical properties, and eventually decreasing its strength and ductility capacity. In addition, earthquakes represent one of humanity's most threatening natural disasters. The seismic performance of structures subjected to corrosion and located in highly seismic regions is of great concern. A reasonable damage model that could accurately estimate and predict the degree of damage in steel structures subjected to earthquake action would be of great significance for the theoretical development of performance-based seismic design. In this paper, we conducted accelerated corrosion experiments in an acid atmospheric environment on three standard steel specimens of different thicknesses and then conducted tensile tests on corroded steel specimens to obtain the degradation laws of steel's mechanical properties for increasing rates of weight loss. By considering both the component-section loss and the degradation of the material mechanics, we built finite element analysis models of steel frame structures with different degrees of corrosion. Then, to characterize the structural damage caused by corrosion, we conducted a nonlinear static pushover analysis to obtain the degradation law of the initial stiffness of entire structures with increasing degrees of corrosion. By establishing a two-parameter seismic damage model that considers both the greatest deformation and the accumulated energy dissipation effect at the whole-structure level, combined with our steel specimen tests and finite analysis results, we developed and propose a time-varying seismic damage model that is applicable to corroded steel structures. We also compared the seismic vulnerability curves of steel frame structures of varying ages and analyzed their inter-story drift angles and time-varying damage models as a seismic demand index. The results indicate that with increases in the degree of corrosion, the structural failure probability of exceedance increases with seismic intensity.

    • Seismic Control Analysis of Large-span Space Structures under Multidimensional Earthquakes

      2018, 40(3):398-405. DOI: 10.3969/j.issn.1000-0844.2018.03.398

      Abstract (821) HTML (0) PDF 8.89 M (931) Comment (0) Favorites

      Abstract:Considering the adverse effect of a multidimensional seismic input on the grid structure, this study proposes an innovative hybrid shape memory alloy viscous damper (HSMAVD) with a large energy dissipation, an amplifying function, and a self-centering capability based on the superelasticity of the shape memory alloy (SMA). Cyclic tension-compression tests on the HSMAVD are performed herein to obtain the mechanical behavior of the damper. A constitutive model suitable for the damper is proposed according to the Kelvin-Voigt model. The corresponding simulation program is compiled by MATLAB and compared with the experimental results. Some members of the grid structure are then replaced by the proposed damper based on the plane quadrangular-pyramid grid model. Subsequently, the vibration control effect of the damper is analyzed. The results show that the SMA and the viscous damper have a good ability to work together and can effectively make use of the hyperelasticity of the SMA and the velocity dependency of the viscous damper. Both have a stable hysteretic behavior and a good energy dissipation capacity. The simulation results are also in good agreement with the experimental data, and the correctness of the proposed model is verified. The method of replacing an original member with a damping member is not only effective in the seismic control of the structure, but also does not change the original structure. As a superior damping control method, it can provide some new ideas for the actual application of the HSMAVD passive control system in the seismic design of a structure.

    • Seismic Performance of Ultra High Voltage Gas Insulated Switchgear Porcelain Bushing

      2018, 40(3):406-412. DOI: 10.3969/j.issn.1000-0844.2018.03.406

      Abstract (1045) HTML (0) PDF 4.16 M (670) Comment (0) Favorites

      Abstract:To evaluate the seismic performance of a porcelain bushing for 1 100 kV ultra-high voltage (UHV) gas-insulated switchgear (GIS), the porcelain bushing with its supporting stand and canister were installed on a shaking table platform, and a shaking table test was carried out on the UHV GIS porcelain bushing. In the shaking table test, an artificial wave that conforms to the UHV standard response spectrum was used to excite the porcelain bushing. The dynamic characteristics of the porcelain bushing, the acceleration and displacement response of the bushing top, and the strain response of the bushing root were obtained. The numerical simulation on the shaking table test was performed using the simulation software ABAQUS, and then the natural vibration frequency of the model, the stress of the bushing root, and the relative displacement of the bushing top were obtained. The values are well consistent with the test results, which proves the efficiency of the numerical model. The influence of the natural frequency of the bushing and stiffness of the body (support cylinder and bracket) on the seismic performance of the bushing were studied by numerical simulation. The results show that the seismic response of the bushing is relatively small when the natural frequency changes within a certain range. The maximum stress of bushing root and maximum relative displacement of bushing top decrease with increase of body stiffness; therefore, the seismic response of the bushing can be reduced through the increase of body stiffness.

    • Panel Structure Instability BIM Model Design of High-rise Buildings under Continuous Vibration

      2018, 40(3):413-420. DOI: 10.3969/j.issn.1000-0844.2018.03.413

      Abstract (813) HTML (0) PDF 7.51 M (999) Comment (0) Favorites

      Abstract:To improve the seismic behavior of the panel structures of high-rise buildings, a BIM model for the panel structure instability under continuous vibration is designed in this study. The high-rise building model and structure model are established based on the Revit program, and then a finite element model of high-rise building structure is constructed by the SAP2000 software. An overall structure of the IFOD software of BIM model is designed to realize an intelligent management of BIM model. Based on the BIM model, the wind-induced response of panel structure of high-rise buildings under continuous vibration is analyzed, and the average wind-induced response and fluctuating wind-induced response of panel structure of high-rise buildings are obtained. Therefore, the stability analysis of the panel structures of high-rise buildings under continuous vibration is realized. The experimental results show that the designed BIM model can accurately analyze the acceleration and displacement time history of high-rise buildings under continuous vibration, and compared with traditional methods, the proposed method judges the stability of panel structures under continuous vibration more accurately.

    • Static Elastoplastic Analysis (Pushover Analysis) of the Factors Influencing Buckling-restrained Braced Steel Frame Structures

      2018, 40(3):421-431. DOI: 10.3969/j.issn.1000-0844.2018.03.421

      Abstract (843) HTML (0) PDF 3.83 M (855) Comment (0) Favorites

      Abstract:To test the influence of factors such as the lateral stiffness ratio and brace layout forms on the seismic behavior of buckling-restrained braced steel frames with different stories, the seismic performance of three buckling-restrained braced steel frame structures with six, twelve, and eighteen stories were analyzed with the SAP2000 software. The analytical structures have different lateral stiffness ratios with 1, 2, 3, 4, 5 and different brace layout forms with inverted V-shapes and monoclinic directions. The results show that base shear force-roof displacement curves of different buckling-restrained braced steel frame structures present typical bilinear relation. Furthermore, by increasing the lateral stiffness ratio, the story drift ratio of the structure, the roof horizontal displacement, and the shear force of the frame decreased, but the base shear force and the brace axial force increased. The structures with inverted V-shape braces had slightly larger base shear forces and spectral accelerations, but they had smaller roof horizontal displacements, story displacements, interstory shear forces, and shear-sharing ratios of frames than those of the structures with monoclinic layout braces. The analysis generally indicates that the structures with inverted V-shape braces have better seismic performance than the structure with monoclinic layout braces. Lastly, the results show that the lateral stiffness ratio has more significant influence on the seismic behavior of buckling-restrained braced frame structures than the brace layout forms.

    • Dynamic Characteristics of Masonry Structure of Low-rise Buildings under Earthquakes

      2018, 40(3):432-437. DOI: 10.3969/j.issn.1000-0844.2018.03.432

      Abstract (755) HTML (0) PDF 7.81 M (873) Comment (0) Favorites

      Abstract:The traditional methods of analyzing the dynamic characteristics of masonry structure in low-rise buildings are easily disturbed by the external environment, and masonry structures have poor structural integrity, which leads to low accuracy of dynamic characteristics analyses. To improve the seismic performance of masonry structures in low-rise buildings, a method for dynamic analysis of masonry structure in low-rise buildings under earthquake is proposed in the study. First, the natural frequency of the masonry structure is identified using the auto-power spectrum of the masonry structure of low-rise buildings. Then the natural frequency is tested by a 941 B ultra-low frequency vibrometer, and the area of noise interference in the vibration waveform can be selected to obtain the time domain and frequency domain waveforms. Finally, a 3D refined model of masonry structure is established according to the time domain and frequency domain waveforms. Based on the model, the simulation results of low story masonry structure are obtained by a subspace iteration algorithm, and the influences of core column, ring beam, and other structural measures on the dynamic characteristics of masonry structure under earthquakes are analyzed. The experimental results show that the proposed method analyzes the dynamic characteristics of masonry structure in low-rise buildings under earthquakes more accurately than traditional methods.

    • Fast and Efficient Multi-Dimensional Pseudo-Excitation Method for Seismic Calculation of “Building-Bridge Integration” Railway Station

      2018, 40(3):438-443. DOI: 10.3969/j.issn.1000-0844.2018.03.438

      Abstract (827) HTML (0) PDF 5.32 M (744) Comment (0) Favorites

      Abstract:A building-bridge integration railway station features many nodes with obvious spatial interactions; therefore, any calculation method used to calculate seismic responses for this type of station needs to have a high computing efficiency. In addition, it needs to enable consideration of the correlation between modal shapes, seismic excitation, and variations in the input angle of seismic excitation. In this study, based on power spectrum formulas along the direction of the structural global coordinate system and the determination method of the rational spectral intensity factor, this study proposes a fast and efficient multi-dimensional pseudo-excitation method that calculates seismic responses of the building-bridge integration railway system and considers variations in the seismic excitation angle. Using Region-Ⅱ of Tianjin West Railway Station as an example, calculated results of the structural response obtained from our proposed method are compared with those using the time-history analysis method and the existing pseudo-excitation method. Results are in good agreement with each other and show that the fast, multi-dimensional, pseudo-excitation method is rational, and its computational efficiency is significantly improved compared with the existing pseudo-excitation method. Therefore, the method is considered to be more suitable than others for making seismic calculations of a building-bridge integration railway station under earthquake excitation.

    • Seismic Stability Analysis of Concrete Structures Based on Hysteretic Curves and Structural Dynamic Equations

      2018, 40(3):444-449. DOI: 10.3969/j.issn.1000-0844.2018.03.444

      Abstract (857) HTML (0) PDF 1.28 M (1123) Comment (0) Favorites

      Abstract:To accurately and comprehensively analyze the seismic stability of concrete structures in civil engineering buildings, a method for seismic stability analysis of concrete structures based on hysteretic curves and structural dynamic equations is proposed. A hysteretic curve is first used to describe the damage of concrete structures under an earthquake, and the inflection point of the hysteretic curve model is operated effectively to ensure an effective analysis of the seismic stability of concrete structure by using a dynamic equation. Then the seismic stability analysis method based on the dynamic equation of concrete structure is adopted. Based on the earthquake ground motion model and structural analysis model, the random seismic response of concrete structures is analyzed, and the total amount of the random seismic response is obtained. Then the probability expression for calculating the seismic stability of concrete structures is derived based on the principle of structural stability. Based on this expression, the seismic stability of concrete structures is analyzed. The experimental results are accurate and comprehensive, indicating that the proposed method can effectively analyze the seismic stability of different types of concrete members in civil engineering buildings.

    • Experiments on the Seismic Behavior of Thin-Walled Steel Tube/Bamboo Plywood Composite Columns

      2018, 40(3):450-457. DOI: 10.3969/j.issn.1000-0844.2018.03.450

      Abstract (738) HTML (0) PDF 10.80 M (592) Comment (0) Favorites

      Abstract:The development of laminated-bamboo has broadened the applications of bamboo material in structural engineering. An assembling composite hollow column parallel to the fiber texture is composed of square thin-walled cold-formed steel tube/bamboo plywood reinforced by transverse binding bars and structural adhesive. The thin-walled steel-tube/bamboo plywood assembling composite hollow columns with binding bars (SBCCBs) are a new type of steel/bamboo composite with excellent physical and mechanical properties. Multi-layered high-strength bamboo plywood forms the primary body in an SBCCB that is subjected to forces, while the square thin-walled steel tube serves as a liner. Large numbers of bamboo are used, which reduces the manufacturing cost of the composite columns and results in a relatively high load-bearing capacity. Nine thin-walled SBCCBs were used to perform low-cyclic reversed quasi-static loading tests, and their damage process and failure modes were investigated. The influence of the shear-span ratio, net cross-sectional area, sectional combination mode of SBCCBs on the bearing capacity, and seismic behavior were analyzed. The results indicate that the failures of SBCCBs are primarily the cracking damage between the gluing interfaces and the fracture damage of plywood material at the foot of column. The sectional combination mode had a significant influence on the failure mode, and the seismic behavior of SBCCB can be improved by increasing the net cross-sectional area and slenderness ratio of the composite hollow columns. SBCCBs have good elastic deformation and seismic energy dissipation capacities, and the binding bars can effectively guarantee the integrity of SBCCB and suppress the gluing failure between the matrix interfaces. SBCCB specimens showed an excellent seismic performance and can be used as the vertical bearing element of a multi-story, pre-fabricated, column-supported, and bamboo-framed wood building.

    • Seismic Site Effect of Circular Underground Cement—Soil Pile Foundation Considering Multi-factor and Complex Parameters

      2018, 40(3):458-465. DOI: 10.3969/j.issn.1000-0844.2018.03.458

      Abstract (762) HTML (0) PDF 4.41 M (852) Comment (0) Favorites

      Abstract:To accurately analyze the seismic site effect of circular underground cement—soil pile foundations and improve the seismic performance of buildings, in this study, we used ABAQUS finite element software to analyze the seismic effect on circular underground cement—soil pile foundations with different random parameters. Specifically, we analyzed the parameters used in the calculation, the geological conditions of the site, and the equivalent composite soil parameters. Using a simplified model of a two-dimensional composite modulus, we discuss the influences of the reinforcement depth, a newly built structure on the foundation, the topography of the underlying bedrock, and some random parameters (e.g., modulus of cement soil, seismic attributes, and different scenes) on the seismic site effect. The experimental results show that the peak acceleration response on the circular underground cement—soil pile foundation decreases with increased reinforcement depth of the cement—soil pile and composite modulus, and is significantly lower than that on a free field. A new structure on the foundation experiences a strong disturbance in the ground motion characteristics around the foundation, and the interference amplitude and area have a high correlation with the structure scale. We found a certain correlation between the bedrock terrain at the bottom of the foundation and the ground motion characteristics of the upper foundation. The influence of soil conditions on the seismic effect of the composite foundation is great, whereas the influence of the pile modulus is relatively small.

    • Simulation of Force Analysis Model for Foundation Pit Pile under Seismic Impact

      2018, 40(3):466-472. DOI: 10.3969/j.issn.1000-0844.2018.03.466

      Abstract (883) HTML (0) PDF 1.33 M (882) Comment (0) Favorites

      Abstract:At present, when using the improved dynamic Winkler model to analyze the stress conditions of foundation pit piles from earthquake shock, the reflection effect of the stress wave cannot be prevented, which renders the analysis result noncomprehensive and inaccurate. In this paper, we propose a stress analysis model for foundation pit piles subjected to seismic impact. We use a small strain model for foundation pit piles to describe the modulus change of the pile under different stress states, and use the finite element numerical simulation method to establish a finite element model for foundation pit piles in combination with the small strain model. When setting the boundary condition constraints of the finite element model for foundation pit piles, we choose an absorbent boundary of viscous dampers to prevent the refraction of the stress wave on the model boundary, and thereby avoid calculation error. We use the Newmark method to analyze the dynamic time history of the finite element model and determine the stress of foundation pit piles under different stress states. The experimental results show that the proposed model can effectively and accurately analyze the stress distributions of foundation pits and the bending moments and deformation displacements of the piles.

    • Dynamic Performance of Pile Foundation in Loess During Strong Earthquakes

      2018, 40(3):473-479,489. DOI: 10.3969/j.issn.1000-0844.2018.03.473

      Abstract (751) HTML (0) PDF 2.89 M (701) Comment (0) Favorites

      Abstract:The traditional p-y curve method for analyzing the dynamic behavior of pile foundations in loess during strong earthquakes does not simulate the pile foundation structure, so the relevant dynamic parameters of the pile foundation in loess are inaccurate. In this paper, we present a new dynamic analysis method for pile foundations in loess during strong earthquakes. We designed a hardening soil-small (HSS) constitutive model based on the hardening soil (HS) model, and obtained the related parameters of the pile foundation in loess during strong earthquakes through the constitutive model. Then, using PLAXIS software, we constructed a finite element model of the pile foundation in loess. Based on these two models, we conducted experiments on pile foundations during strong earthquakes to analyze their horizontal displacement responses and the internal forces in the pile body under the coupled load. The experimental results show that the proposed method can accurately analyze the dynamic characteristics of pile foundations in loess during strong earthquakes.

    • Effect of Irregularity on the Progressive Collapse Resistance of Base-isolated Structures

      2018, 40(3):480-489. DOI: 10.3969/j.issn.1000-0844.2018.03.480

      Abstract (867) HTML (0) PDF 11.53 M (735) Comment (0) Favorites

      Abstract:To study the anti-progressive collapse performance of base-isolated structures, the static nonlinear and static linear methods are used to analyze the structure of a typical vertical, irregular reinforced concrete foundation using static load method. Based on the anti-progressive collapse mechanism and the demand ability of the backup load path, the anti-progressive collapse performance of the vertical, irregular reinforced concrete base-isolated structure was studied to provide a reference for the anti-progressive collapse design of base-isolated structures. To further study the irregularity of structural arrangements and the influence of the change of podium and tower layers on the progressive collapse of the vertical, irregular isolated structure, the corresponding models were established, and a comparative study was performed. The result shows that except for the corner column, the alternative load path showed a significant catenary mechanism in the Pushover process after the initial failure occurrence of all other columns. When the isolation bearing failed because of the small horizontal stiffness of the isolation layer, adjacent bearings could not provide sufficient lateral constraints to form a catenary mechanism. The ability of the remaining structures to resist progressive collapse can be effectively improved by increasing the structural redundancy and the number of components with alternative load paths. Except the corner column and the corner bearing the initial failure condition, the DCR value of the isolation bearing failure condition is generally larger than the value of the bottom frame failure condition at the corresponding position, and the failure risk of some components in the alternative load path of the isolation bearing failure condition was relatively large.

    • Optimization Research on a Seismic Analysis Model of Building Structures

      2018, 40(3):490-496. DOI: 10.3969/j.issn.1000-0844.2018.03.490

      Abstract (773) HTML (0) PDF 6.29 M (851) Comment (0) Favorites

      Abstract:Most building structures consist of main structures such as beams, columns, braces, shear walls, foundation, and floors. Generally, the seismic performance of the floor slab to the building structure is negligible; therefore, analysis models of building structures do not consider floors, and the floor slab is replaced by a rigid baffle to increase the analysis efficiency. The seismic analysis model of building structures proposed in this paper considers the bending stiffness of the floor. The model uses super element, rigid baffle, and substructure technique to reduce the degree of freedom. Through an example analysis, the validity and accuracy of the model in the seismic analysis of multi-story building structure are verified. The proposed model can significantly reduce computational complexity and improve analysis efficiency. Moreover, the accuracy of the analysis results, such as the vibration cycle and response time, is very close to the result of the refined model, which substantiates the efficiency of the proposed model.

    • Discussion of Seismic Waves Selection Method for Isolation Structures

      2018, 40(3):497-503,581. DOI: 10.3969/j.issn.1000-0844.2018.03.497

      Abstract (784) HTML (0) PDF 5.92 M (1431) Comment (0) Favorites

      Abstract:Most isolation structure designs are based on a time-history analysis, which is greatly affected by earthquake waves. At present, the non-isolated model is most often used in isolation structure design, but this contains certain irrationalities. In this paper, three types of schemes based on two different models (isolated and non-isolated models) are proposed to select earthquake waves, together with different control frequency ranges of seismic response spectrum. Twenty seismic waves are selected in accordance with the three schemes, and these are input in a five-story base-isolated concrete frame structure. The discreteness of horizontal seismic reduction coefficients of the structure is then compared. Furthermore, displacements of the isolated bearing of the structure under a rare earthquake are analyzed. Results show that the third scheme provides optimal calculation results. A three-frequency range method for selecting waves based on different frequency ranges of code design response spectrum is then proposed, and five engineering examples with different structures are selected to verify the applicability of the method. Results show that the method is suitable for use with common structures.

    • Earthquake Response Analysis for Loess Sites in Far-Field of Wenchuan Earthquake

      2018, 40(3):504-511. DOI: 10.3969/j.issn.1000-0844.2018.03.504

      Abstract (877) HTML (0) PDF 13.10 M (1057) Comment (0) Favorites

      Abstract:In recent years, several studies have been conducted on the effect of far-fault ground motions on deep soft soil sites; however, relevant research works for thick loess sites are still seldom. The Loess Plateau is seated on the upper and middle stream of the Yellow River in North China, covering an area of 440 000 km2, and the thickness of loess is up to above 500 meters. More than 1.4 million people have been killed by the earthquakes in this region, among which is the Wenchuan MS8.0 earthquake of 2008, which led to collapse of infrastructures, tremendous casualties, and economic losses. However, according to field investigations, observations, and analyses, the collapse and damage of buildings were not only caused by poor seismic performance or landslides, but also by amplified effects of site conditions, topography, and thickness of loess deposit on ground motion. In this paper, to explore the relationship between amplification factors and site conditions in terms of thickness of loess deposit, we chose a typical loess site for numerical analysis. Based on the drilling data of actual engineering sites, this paper selects 45 typical site profiles. Using the one-dimensional equivalent linear fluctuation method, the ground surface acceleration responses of each site were calculated under the input of ground motions with three different intensities. The results indicate the following: (1) Under the far-field ground motion, the PGA of loess site is large, and the platform of response spectrum is wide, mostly in 0.2~0.6 s; (2) the PGA decreases with increase in the loess thickness, but the earthquake damage on structures with natural periods above a certain range is aggravated; (3) for thick loess areas without topography, with increase of the loess thickness (20~100 m), the value of the descending segment of response spectrum amplifies 1.1~1.4 times, and the characteristic period amplifies 1.1~1.25 times. The numerical result is basically consistent with the field investigation; therefore, it is of great scientific and practical importance in earthquake engineering for seismic fortification in loess regions.

    • Experimental Study on the Freezing Strength Characteristics of Clay-Structure Interface in Cold Regions

      2018, 40(3):512-518. DOI: 10.3969/j.issn.1000-0844.2018.03.512

      Abstract (723) HTML (0) PDF 1.27 M (632) Comment (0) Favorites

      Abstract:Frozen soil is a composite material composed of soil particles, ice, unfrozen water, and gas, and with unstable mechanical properties. The amount of ice determines its temperature sensitivity, and previous research has shown that its negative temperature is the most critical factor that determines its strength; therefore, temperature is a key factor in regulating the bearing capacity of a frozen soil foundation. As the main foundation of major constructions in unstable and ice-rich permafrost regions, a pile foundation is widely used because of its relative stability during permafrost degradation. The freezing strength of a soil-structure interface in the cold regions can be viewed as a complicated functional form of the soil property, temperature, water content, interface roughness, and normal pressure, which directly influence the bearing capacity and stability of the upper structure. Series of laboratory direct shear tests of the interface between the Qingzang Clay and a steel plate of different roughness were performed. Based on the direct shear tests and an orthogonal design method, the influence factors, influence degree, and mechanical behavior of the shear strength of soil-structure interface were studied. The results show that the amount of water content in the interface has the greatest influence on its shear strength. From laboratory tests, the maximum and minimum interfacial shear strength is 0.45 MPa and 0.13 MPa, respectively, under the different test conditions. Moreover, the shear strength of interface decrease with increasing water content and temperature, and the shear strength increase with increase in the interface roughness and normal pressure. Based on the experimental results, the shear strength of interface can be determined based on Mohr-Coulomb strength criterion; the cohesive strength and internal friction angle are presented in this paper. The results of this study can help prevent and control the disasters of pile foundations at permafrost regions; thus it is of great scientific importance.

    • >地震科学研究与观测
    • Discussion on the Tancheng M8 1/2 Earthquake of 1668 Based on the Intersection of Epicenter Migration: For the 350th Anniversary of Tancheng Earthquake

      2018, 40(3):519-523. DOI: 10.3969/j.issn.1000-0844.2018.03.519

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      Abstract:The location of the meizoseismal area of the Tancheng M8 1/2 earthquake in 1668 corresponds with the result based on the intersection of epicenter migration of earthquakes with a magnitude of 43/4~51/2. It is easier to find the geographic range of the M8 1/2 earthquake source using the intersection of epicenter migration. Moreover, the reason for the Tancheng earthquake's high magnitude is discussed in this study.

    • Preliminary Study on the Wave Velocity Ratio (vP/vS) in Hainan Island and Offshore Areas

      2018, 40(3):524-534. DOI: 10.3969/j.issn.1000-0844.2018.03.524

      Abstract (677) HTML (0) PDF 22.53 M (616) Comment (0) Favorites

      Abstract:The observation of the earthquake cluster from 1990 to 2015 in Hainan Island and its coastal areas was collected based on the idea of a "generalized repeat earthquake". This study investigates the wave velocity ratio (vP/vS) of the earthquake cluster zone to different stations around using the single station-single earthquake method and preliminarily analyzes the physical properties of the subsurface medium in the study area. The results showed that: (1) The average wave velocity ratio of the earthquake cluster to the single station was lower than 1.732. Before and after 2008, significant differences were found in the variation characteristics of the average velocity ratio and the velocity ratio with time, which may be related to the stress adjustment after the long-period seismic activity in the study area during 2007—2008 and to the stress transfer of the 2008 Wenchuan earthquake. (2) The vP/vS ratio was affected by the crushing degree and the rheological property of the subsurface medium. A high rupture degree of underground rocks and a strong rheological property of the medium may cause a relatively high velocity ratio of stations, such as the QXL, DOF, CHM, and NAD stations. (3) The underground medium in the uplift area of the central-southern Hainan was compact and stable. Aside from the NAD, CHM, and DOF stations in the special medium area, the wave velocity ratio of the other stations showed relatively low values in this area. (4) Before and after 2008, differences in the apparent velocity features and the seismic activities in different seismic cluster zones were found, which may indicate that the study area was in a state of stress adjustment. The different apparent velocities in the east and west sides of the Puqian—Qinglan fault were mainly affected by different lithologies and the thermal process in volcanic areas.

    • Analysis of Gravity Earth Tide Using a New Intelligent Optimization Algorithm and Spectral Correlation Method

      2018, 40(3):535-541. DOI: 10.3969/j.issn.1000-0844.2018.03.535

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      Abstract:To reveal harmonic components in the Gravity Earth Tide, this paper establishes a 3D orthogonal decomposition model according to the relationship between the moon and the sun relative to the Earth's position. To improve calculation efficiency and global optimization ability, an intelligent optimization algorithm is proposed based on the surface-simplex swarm evolution algorithm. Through combing of the spectral correlation method, observation data for the Gravity Earth Tide are processed and analyzed, and changes in the frequency and time domain are observed. Furthermore, theoretical signals and calculations are introduced as a reference background to highlight abnormal variations. Through analysis of observation data recorded in the Yunnan area from April 1, 2001 to December 1, 2001, characteristics of daily wave, semi-diurnal wave, and long-period wave of Gravity Earth Tides are effectively extracted. Furthermore, hidden earthquake precursor information is found to exist in abnormal changes of the Gravity Earth Tide. After excluding measurement errors and environmental impact, long-period gravity solid tide waves are found to show regular abnormal changes within two to five months before an earthquake. The results show that the proposed method can effectively analyze Gravity Earth Tide signals and reflect abnormal precursor information occurring prior to earthquakes, thereby providing a new method of earthquake prediction.

    • Random Field Features of Seismic Activity

      2018, 40(3):542-548. DOI: 10.3969/j.issn.1000-0844.2018.03.542

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      Abstract:Seismic activity is a random natural phenomenon. When variables of basic elements of seismic activity are taken as temporal and spatial functions they are found to have basic random field features. This paper discusses the statistical features of energy and frequency fields of seismic activity under certain conditions, in addition to stationary problems found within the seismic activity field. Results show that it is rational to use the random field method to study seismic activity. Through a discussion of the energy distribution of seismic activity and statistical characteristics of the time distribution of earthquakes, the following conclusions are drawn: (1) Seismic activity has random field distribution characteristics and can be seen as a type of random field; therefore, it is possible to conduct quantitative mathematical studies of seismic activity using the random field method. (2) The logarithmic values of energy released by seismic activity obey the distribution law of the exponential function expressed in the paper; however, the distribution laws differ in different regions due to influence of the b value. (3) Under the condition of stationary activity, the temporal distribution of small earthquake activity in a certain region obeys the poisson distribution. (4) In most cases, the statistical characteristics of seismic activity can be basically maintained, as long as the regional stress distribution has not subversively changed, and seismic activity in this region can be considered to be in a stable state.

    • Mathematical Modeling Analysis and Simulation of Variations in Seismic Wave Intensity

      2018, 40(3):549-554. DOI: 10.3969/j.issn.1000-0844.2018.03.549

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      Abstract:When the traditional grey prediction method is used to model and simulate variation in seismic wave intensity, the series of the variation is predicted without analyzing the time attribute of earthquake wave intensity. Hence, the accuracy of the analysis result is low. A new mathematical modeling analysis and simulation method for these variations is proposed in this paper. The threshold value of the threshold autoregressive model is determined by the empirical distribution of the seismic wave intensity series. The threshold autoregressive model of seismic wave intensity series is obtained by using the threshold value of the minimum criterion AIC and the least residual square method. The characteristics of limit cycles and oscillations of the auto-regressive model are analyzed, and the seismic wave intensity is obtained. The mathematical model of seismic wave intensity series is constructed based on the mean generating function. The time series of the earthquake wave intensity is fitted by using the mean generation function. The fitting period is selected based on the double score criterion according to the time series. An accurate numerical simulation of seismic wave intensity is realized. The experimental results show that the proposed method is accurate and stable for the seismic wave intensity variation model.

    • Probabilistic Seismic Hazard Analysis Based on Arias Intensity: A Case Study in Danling County, Sichuan Province and Its Surrounding Area

      2018, 40(3):555-561. DOI: 10.3969/j.issn.1000-0844.2018.03.555

      Abstract (665) HTML (0) PDF 14.64 M (765) Comment (0) Favorites

      Abstract:Arias Intensity is a ground motion parameter that contains amplitudes, frequencies, and duration of ground motion. It is more reliable in some predictions of seismic damage than the parameters that only depend on the amplitude of ground motion. Scientists have shown that Arias Intensity has a strong correlation with landslides induced by earthquakes. This study presents a preliminary probabilistic seismic hazard assessment in terms of the Arias Intensity in Danling County, Sichuan Province using a seismic source model and the seismicity model established by the Seismic Ground Motion Parameters Zonation Map of China. The results show that the Ia value for most of Danling County and its surrounding area is above 0.11 m/s. Some parts of the area has a value of 0.32 m/s. Some even has more than 0.54 m/s, where a relatively high hazard of earthquake-induced landslides can be found. Hence, we should strengthen the risk assessment of earthquake-induced landslides in personnel concentration areas. An obvious difference is found in the calculation of the Ia distribution according to different Ia prediction equations. Therefore, we should consider more than one Ia prediction equation when calculating the Ia value. The weighted average of the final results is derived to reduce the uncertainty of the Ia value. We also find a strong correlation between Ia and spectral acceleration (t=1.0 s), which confirm the correlation between sand liquefaction and Ia.

    • Study of the Recent Crustal Horizontal Deformation in the Northern Segment of the North-South Seismic Belt Based on GPS Data

      2018, 40(3):562-573. DOI: 10.3969/j.issn.1000-0844.2018.03.562

      Abstract (781) HTML (0) PDF 24.08 M (776) Comment (0) Favorites

      Abstract:To study the characteristics of the recent crustal horizontal deformation in the northern segment of the North-South seismic belt, the GPS velocity field in the northern segment of the North-South seismic belt (33°~42°N, 97°~110°E) since 1999 was computed based on the GPS data from stations of the Crustal Movement Observation Network of China using the GAMIT/GLOBK software. These findings, combined with information on the seismic activities in the study area, suggest that M≥8.0 earthquakes will likely occur in the northern segment of the North-South seismic belt in the next 50 years; the fourth active period of earthquakes since 1900 with magnitude 6~7 may have already arrived, and in the next two years, an M>7.0 earthquake may occur; there is potential risk of M6 and M7 earthquakes in the Qilianshan, northern Xiqinling, and especially Haiyuan faults.

    • Design and Implementation of an Earthquake Early Warning Network System Based on Cloud Computing

      2018, 40(3):574-581. DOI: 10.3969/j.issn.1000-0844.2018.03.574

      Abstract (723) HTML (0) PDF 1.48 M (682) Comment (0) Favorites

      Abstract:The traditional seismic early warning network system based on data fusion has to analyze a large amount of seismic data for providing early warning. This system has the disadvantages of high seismic warning deviation and poor dynamic monitoring performance. Therefore, an earthquake early warning network system based on cloud computing is designed. The "Software as a Service" (SaaS) technology is used to design the system, and the seismic wave information is collected by a seismic monitoring sensor module with STM32F103RET6 MCU core. The system adopts concurrent filtering and receiving technology for multiregional seismic data to receive and process massive data in time and effectively. For system implementation, the software architecture of the system is designed as follows: based on the seismic wave simulation display model of a Web page, Highcharts JS software in the browser is used to simulate the seismic waveform. The experimental results show that the designed system can accurately provide early warning of an earthquake and has strong dynamic monitoring performance.

    • >其他
    • Shaking Table Test on Seismic Dynamic Responses of Isolated Mountains

      2018, 40(3):582-590. DOI: 10.3969/j.issn.1000-0844.2018.03.582

      Abstract (730) HTML (0) PDF 3.02 M (561) Comment (0) Favorites

      Abstract:This paper conducts a large-scale shaking table model test of an isolated mountain on a scale of 1∶10. The model is constructed using soil and has a height of 1.8 m, length of 4.4 m, width of 4.4 m, and four slope angles of 30°, 45°, 50°, and 60°. A series of tests are performed with different input seismic wave types, amplitudes, and frequencies. Dynamic response characteristics of isolated mountains under earthquakes are discussed, as well as the influence of ground motion parameters. Conclusions obtained are as follows: (1) the topographic amplification effect of peak accelerations in the vertical direction and free-surface direction gradually increases with an increase in the slope angle: when the slope angle is 45°, the amplification effect of peak accelerations suddenly increases but decelerates when the angle is 50°. However, there is minimal change in the amplification effect of peak acceleration along the slope strike direction with an increase in the slope angle. (2) There is a gradual reduction in the topographic amplification effect of peak accelerations in the vertical direction, free-surface direction, and slope strike direction with an increase in the peak ground accelerations of the input wave, revealing an intensity saturation phenomenon. These results reveal the mechanism of slope instability under earthquakes and can be used as a reference for seismic design during slope engineering.

    • Influence of Construction Disturbance from Close Upper Tunnel on Lower Tunnel

      2018, 40(3):591-596,603. DOI: 10.3969/j.issn.1000-0844.2018.03.590

      Abstract (776) HTML (0) PDF 6.00 M (970) Comment (0) Favorites

      Abstract:Based on the mechanical model of a simply supported beam, this study investigates the influence of periodic construction disturbances from a close upper tunnel on the vibration characteristics of the roof of a lower tunnel. The mathematical expression for the dynamic response of vertical displacement at the top of lower tunnel is deduced. The mathematical expression can provide a theoretical basis for determining the occurrence time and peak displacement, and provide a method for determining the safe distance between the two tunnels. The law of the action of influencing factors such as the disturbance force on maximum displacement is explored with a specific example. The results show that when the disturbance amplitude and the tunnel span increase by 1 and 2 orders of magnitude, respectively, the corresponding peak displacements increases by 1 and 23.9 orders, respectively and when the vertical distance between tunnel layers and the elastic modulus of soil increase by 2 and 3 orders, respectively, the corresponding peak displacements reduces by 88.2% and 70%, respectively. When the main affecting factors change, the maximum displacement and its oscillations increase, which influences the top stability of the tunnel.

    • Emergency Model Design for Automatic Dispatching of Electric Power in Seismic Areas

      2018, 40(3):597-603. DOI: 10.3969/j.issn.1000-0844.2018.03.597

      Abstract (694) HTML (0) PDF 1012.34 K (528) Comment (0) Favorites

      Abstract:The traditional model for real-time power balance scheduling does not consider the distribution of transmission margin and emergency supplies during the automatic dispatching of power. Emergency power dispatch incurs high cost and has low efficiency. This results in an increase in the economic loss in the earthquake-stricken area. In this study, a two-layer emergency model for automatic electric power dispatching in seismic areas is designed. The upper level model (the automatic emergency dispatching model) can realize different regulation quantities of the generator according to the transmission margin sensitivity of the multisection static security coordination mode and the real-time power scheduling decision. Thus, the model enhances the transmission capacity of the power grid. Through the lower level model (the power emergency resource dispatching model), by using the minimum cost objective function for emergency electric power dispatching, the quantity constraint conditions of emergency electric power are created, and the scheduling cost of emergency power is minimized. The experimental results verify that the designed model helps the power system realize a higher transmission margin, reduces prevention and correction operations, and enhances the benefits of the automatic emergency dispatch of electric power.

    • Design of a Damage Degree Estimation Model in Earthquake-prone Areas Based on Big Data

      2018, 40(3):604-611. DOI: 10.3969/j.issn.1000-0844.2018.03.604

      Abstract (786) HTML (0) PDF 6.17 M (956) Comment (0) Favorites

      Abstract:The traditional earthquake damage degree estimation models based on geographic information system are inefficient in analyzing and processing big data, and they result in a non-ideal evaluation. Therefore, considering a big data environment, a damage degree estimation model in earthquake-prone areas is designed in the study. The model structure is composed of data service layer, business model layer, and application display layer. The model is composed of six functional structures: basic data control module, seismic hazard module, structural failure module, loss assessment module, decision control module, and document control module. The logical process and page display result of direct economic loss module are designed in the model. The module utilizes a random weight neural network to rapidly assess earthquake damage degree in a big data environment. The experimental results show that the designed model can effectively and accurately evaluate the destruction degree in earthquake-prone areas under a big data environment.

    • Local Compressional Behavior of Circular Tubed High Strength Grouting Material

      2018, 40(3):612-618. DOI: 10.3969/j.issn.1000-0844.2018.03.612

      Abstract (822) HTML (0) PDF 5.02 M (627) Comment (0) Favorites

      Abstract:In early experiments, the authors researched the force characteristics and failure modes of high strength grouting material in circular tubes with different thicknesses and forms. It was determined that the failure mode of the test pieces is that of shear failure and that the ultimate bearing capacity of the test pieces increases with an increase in the thickness of tube. Based on experiments on the local compression behavior of circular tubed high strength grouting material, a numerical simulation is conducted by establishing a multi-section model (MSM model) using the ABAQUS finite element computing platform. In addition, the mechanical properties of high strength grouting material confined by circular steel tube under local compression are investigated. Load-displacement curves calculated by the software are then compared with experimental results. Results show that the MSM model is applicable for conducting numerical simulations of circular tubed, high strength, grouting material under local compression. Calculated results are in good agreement with test results, and the bearing capacity can be improved by an increase in the following: the height-to-diameter ratio of samples, thickness of the steel tube, and strength of the high strength grouting material.

    • Pressure-bearing Characteristics of Blockboard Building Materials under Strong Earthquakes

      2018, 40(3):619-624. DOI: 10.3969/j.issn.1000-0844.2018.03.619

      Abstract (719) HTML (0) PDF 2.51 M (479) Comment (0) Favorites

      Abstract:It is difficult to analyze the pressure-bearing characteristics of wooden building materials, because of their strong nonlinear behavior under strong earthquakes. In this study, a method of analyzing the pressure-bearing characteristics of blockboard under strong earthquakes is proposed. A building material model is designed, and the pressure-bearing characteristics are determined, and then feature extraction is carried out accordingly. Subsequently, comparative tests are carried out under a simulated strong earthquake. Combining the extracted pressure-bearing characteristics of the blockboard building material, the precision, applicable range, and phase of PS point are analyzed. The results show that the pressure-bearing analysis method of the blockboard building material under strong earthquakes can determine fracture location and pressure level of location in the shortest time and accurately evaluate the performance of the blockboard building materials.

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