Abstract:The 16^th European Conference on Earthquake Engineering was held in Thessaloniki, Greece, June 18-22, 2018. In this paper, general information disseminated at the conference is briefly introduced. Recent research progress in four topics is summarized:(1) seismic hazard, engineering seismology, and strong ground motion; (2) soil dynamics, site effects, and microzonation studies; (3) geotechnical earthquake engineering; and, (4) EU-China cooperation in earthquake engineering and risk. Moreover, the trends in application and revision of Eurocode-8; resilient cities, community and infrastructures; lessons from recent earthquakes; large scale facilities for earthquake engineering purpose, and soil-foundation-structure interaction, are discussed. The authors expect the paper may provide a valuable reference for related research fields in our country.

Abstract:To analyze the dynamic stability of embankments along the Qinghai-Tibet railway in permafrost regions under train loads, a two-component acceleration observation of vibration responses at three typical railway subgrade sections in Beiluhe and Erdaogou were performed. The vibration attenuation law and vibration characteristics of the subgrade induced by passenger trains and freight trains were analyzed and compared. The vibration response of subgrades to trains with differing protection forms are discussed. The results suggest that the frequencies of vibration on the subgrade mainly focus on the range of 40 to 80 Hz. The dynamic response of the subgrade is affected, apparently, by the subgrade protection form. The dynamic response of thermosyphon and crushed-rock subgrades is at the minimum, followed, increasingly, by the crushed-rock subgrade and the subgrade without any protection. It is therefore suggested that the subgrade should be protected. This study can provide a measured basis for dynamic stability evaluations of subgrade under train loads of the Qinghai-Tibet railway, and the conclusions can provide a reference for analyzing the dynamic stability of subgrade in permafrost regions.

Abstract:In this study, we performed dynamic triaxial tests to investigate the effect of loading control mode on the dynamic stress-strain relationship of compacted loess at different confining pressures. We also compared the time-history differences between the dynamic stresses and strains of samples under controlled-stress and controlled-strain modes. The results indicate that the dynamic stress-strain relationship in compacted loess accords with that of the hyperbolic model and that the control mode does not change the type of backbone curve of the compacted loess, but significantly affects the fitting parameters. At the same confining pressure, the initial dynamic modulus obtained by strain-control is smaller than that obtained by stress-control. The growth rate of the initial dynamic modulus obtained by strain-control is relatively small and the gap between the two modes increases with increases in the confining pressure. In the process of stress-control and strain-control loading, the dynamic modulus decreases with increases in the loading cycles at a certain load, and the attenuation amplitude is greater under the stress-control mode than under the strain-control mode. For undisturbed soil with a more sensitive soil structure, more accurate test results can be obtained using the strain-control mode.

Abstract:Loess-high filling sites formed by cutting off hilltops exert a large influence on the characteristics of the ground motion parameters. Based on an actual project, calculation sections with different filling heights were constructed, and the one-dimensional equivalent linearization method was used to calculate the ground motion parameters of soil layers to analyze the influences of bedrock ground motions and height of the filling soil on the ground surface amplification effect. The seismic amplification coefficient of the site decreased with increasing filled height. In addition, the seismic amplification coefficient of the site decreased faster under the action of frequent and basic earthquakes than under the action of rare and extremely rare earthquakes. When the filled height reaches a certain level, the amplification effect stabilizes; variations in filled height change the shape of the surface acceleration response spectrum. At a certain filled height, the bedrock type shows no obvious influence on the surface ground motion characteristics. This research provides a reference for seismic safety evaluation and structural seismic design of loess-high filling sites.

Abstract:The input interface selection has a significant influence on the ground motion parameters in seismic response analyses. Based on borehole profiles in Tangshan area, the top surfaces of rocks with shear-wave velocities of 500 m/s and 800 m/s are chosen as the input interface. Then the effect of input interface in medium-stiff soil site on ground motion parameters are discussed using the 1D equivalent linear method. The results show that (1) the peak ground acceleration magnification and the characteristic period of the surface acceleration response spectrum both increase with the depth of input interface, and the increment is closely related to the intensity and spectral characteristics of the input ground motion; (2) with the increase in the input interface depth, the surface acceleration response spectra almost increase in full frequency range and decrease only in some short period with a limited amplitude; (3) it is appropriate to choose the interface of soil with 800 m/s shear velocity as the input interface in seismic response analyses.

Abstract:The accurate prediction of spudcan penetration resistance plays an important role in the safety of work on Jack-up drilling platforms. In this work, by carrying out small-scale model tests, the influence of penetration speed on the pile-penetration performance of bucket spudcans in saturated sand was studied, and a computational formula for calculating the bucket spudcan penetration resistance was developed based on the bearing capacity of the ground. Subsequently, the penetration process of the bucket spudcan was simulated by the coupled Eulerian-Lagrangian (CEL) finite element method, and the results were compared with test results. The investigation results showed that, when the penetration speed of the spudcan is 0.1~0.3 mm/s in the model test, the penetration process of the bucket spudcan can be regarded as a quasi-static process, and the penetration resistance varies little. The penetration resistance of the bucket spudcan at a certain depth can be calculated accurately by using the Hansen and Vesic formulas. The CEL finite element method can simulate the bucket spudcan penetration process exactly, and the simulation results were in good agreement with the test results when the penetration speed of the spudcan was 0.1~0.3 mm/s.

Abstract:Scientific surveys conducted after the Minxian-Zhangxian M_S6.6 earthquake reveal that the overburden thickness and topographic conditions at local sites in its meizoseismal area have a significant amplification effect on the ground motion. Using a servo velocity seismograph, we conducted a high-density microtremor survey in sites around the meizoseismal area, and obtained the predominant frequencies of the various sites. We used the frequency spectrum analysis method to obtain the overburden thickness distribution of the sites, and investigated the unmanned aerial vehicle telemetry of the area to obtain topographic and geomorphic data. By producing surface and bedrock data from the digital elevation model, we used the Rhino 3D modeler to further process and establish a terrain model and then generated a 3D model of the actual terrain using general finite element software.

Abstract:In the search for more scientifically-sound and economical foundations for seismic subsidence loess sites experiencing strong earthquakes, indoor dynamic triaxial tests were carried out on samples of three types of foundation. The samples were modified through treatment with fly ash, cement soil, and dynamic compaction. The residual strain characteristics of the different foundation modification treatments under strong earthquake conditions were analyzed, and the quantitative relationship between strong earthquakes and residual strain were obtained. The applicability of the three treatment methods were compared from two perspectives:that of deformation characteristics, and that of cyclic number of dynamic load. Based on these tests, the amount of seismic subsidence in the loess site under different methods was estimated, and the proven effective treatment and evaluation methods for different engineering sites under strong earthquake load are given. The study can provide some reference for seismic design and foundation treatment of loess sites.

Abstract:The spectral parameters of a seismic random vibration model have been analyzed based on the Chinese standard code for seismic design of electrical installations (GB50260-2013). In this paper, the design response spectrum in the new code is introduced, and different regulations are made for the seismic effect coefficient curve of different site types. A non-stationary model is established for the process of non-stationary ground motion. The time envelope function is used to consider the non-stationary characteristics of the earthquake, and then the value of the ground motion duration is given. The absolute acceleration under the input of non-stationary vibrations is obtained using the research results of stationary vibrations. The transform process from design spectrum to power spectrum is derived, and the Clough-Penzien model is selected as the fitting function. Using the least square method, the parameters of the power spectrum model corresponding to the design spectrum in the new code are obtained. The fitting power spectrum curve agrees well with the calculated power spectrum curve, indicating that the Clough-Penzien acceleration spectrum can correspond well with the calculated power spectrum curve. By fitting the power spectrum parameters, the parameters of ground motion model under different earthquake intensities and site types are obtained. The research results can provide reference for seismic design analysis in power engineering.

Abstract:In this paper, to accurately evaluate the damage in corroded steel frames under earthquake action, existing seismic damage models are improved and the seismic damage characteristics of frame columns are analyzed. A two-parameter damage model, based on a combination of deformation and energy, is established. The specific definitions and expressions of the corresponding parameters in the damage model are given and the range of damage indexes for different damage grades is defined. Elastic-plastic time-history analyses of three steel frames with different corrosion rates are carried out, and the accuracy of the damage model is verified. The results show that the model describes seismic damage to corroded steel frame columns well. The research results provide a theoretical basis for seismic damage assessment and the establishment of a seismic design method based on damage.

Abstract:The traditional seismic damage model of high-rise buildings cannot reflect the change of ultimate hysteretic dissipated energy with cumulative amplitude; thus, the parameters cannot be effectively determined. Therefore, in this study, a seismic damage model for high-rise buildings under far-field long-period earthquakes was designed. According to the generalized force-generalized deformation curve, a deformation damage model was constructed for high-rise building structures of different levels. By considering both the cumulative energy ratio and the instantaneous input energy ratio of far-field long-period ground motions, an energy damage model was constructed. Based on a comprehensive evaluation of damage from the aspects of deformation and energy, the linear combination seismic damage model of maximum response deformation and dissipated energy was established and modified. Three long-period seismic waves, namely ILA003, ILA048, and TCU115, were selected to calculate the overall damage results of different components and tall buildings and to verify the reliability of the proposed model. The proposed model was applied in practical tall buildings and found to be practical.

Abstract:Based on the effective stress principle of saturated soil, a dynamic model for saturated soil-underground utility tunnels (UUT) interaction is presented. During modeling, the soil was considered as a solid-liquid two-phase media, and the Duncan-Chang constitutive model was used under statistic load, while the Davidenkov model was used when the tunnels were subjected to the action of seismic waves. The viscous-elastic artificial boundary condition of saturated soil was considered, and the ground motions were translated into dynamic load applied to the artificial boundary nodes. The influences of time histories, PGAs, incidence angles of input earthquake waves, porosity of soil, and ground stress fields on the seismic response of UUT were investigated. The following conclusions were drawn from the above analysis:(1) The deformation of structure reaches a maximum when the predominant period of an earthquake wave is close to that of the site, and the deformation of structure increases with increasing PGA and incidence angle of the seismic wave; (2) pore water pressure in the soil is one of main influencing factors in structure deformation; (3) the deformation of structure in single-phase media is much larger than in two-phase media, and the results, based on effective stress methods, were in accord with those based on single-phase media and structure dynamic interaction models subjected to the equivalent load of earthquake waves in saturated soils.

Abstract:In the current method of optimizing the design of spatial building structures, the high convergence of the algorithm makes it impossible to realize multi-objective population optimization, and it is easy to fall into the local optimal solution. The method has the problems of low optimization quality, high optimization cost, and low seismic performance. To solve the above problems, in this work, a method of optimizing the design of spatial building structures based on the improved particle swarm algorithm is proposed, where the seismic performance and engineering cost of space structure are the optimization target. A co-evolutionary multiple sub-groups mechanism was introduced to solve the problem of population optimization among multiple objectives in the optimization of the seismic design of spatial structures. Meanwhile, the elite learning strategy was introduced to improve the particle swarm algorithm. The optimal design scheme satisfying the objective function was selected, and the optimization of the building space structure with seismic constraints was completed. The experimental results showed that the proposed method is characterized by high optimization quality, low optimization cost, and high seismic performance.

Abstract:In this study, we explore the mechanism of wall instability in a building under dynamic load. Based on the theory of elastic mechanics, we analyze the stress field distribution of an unreinforced masonry wall with a rigidly fixed end under the disturbance of vertical seismic waves and obtain the analytical expression of the stress. The results show that the stress characteristics are determined by several factors, i.e., the particle velocity, dead load, density, and geometric size of the wall. We found that the horizontal stress values are 5 and 25 orders of magnitude greater than the shear and vertical stress values, respectively. As such, the horizontal stress is the control stress, and the stress concentration area is located at the top and bottom angles of the wall at the rigidly fixed end. The stress change gradient is 180 MPa/m, and the stress field is further concentrated on the rigid fixed side of the wall with increases in the earthquake intensity. Based on the principle that the principal stress leads to wall cracks, we predict the distribution positions, lengths, and angles of open wall fractures, and identify the most vulnerable parts of the wall. The results of this study can provide a reference for further investigation of the mechanical behavior of walls under dynamic load.

Abstract:Based on the basic principles of dynamics, a simplified dynamic mechanical model with multiple degrees of freedom was established for an irregular bridge. The dynamic equation of the model was derived according to Lagrange's equations. Combined with Runge-Kutta method, the seismic behavior of irregular bridges under traveling wave excitation were studied using a self-compiled program, while considering the influence of some nonlinear factors, i.e., the bearings friction sliding and structural pounding. The results show that the combined action of traveling wave effect and pounding effect can increase the bending moment of short piers. The traveling wave excitation can increase the rubber bearing displacement, and the increase in peak displacement of the bearing above the last pier the seismic wave reaches is most obvious. Under the action of earthquake, the laminated rubber bearing above short piers is prone to slide; therefore, in anti-collision designs of irregular bridges, the traveling wave excitation and bearings friction sliding should be considered to find out the maximum pounding force of adjacent structures, in order to guide the design of irregular bridges.

Abstract:To improve the seismic performance of out-of-code high-rise buildings and minimize earthquake loss, in this work, we propose detailed measures and suggestions for strengthening the seismic design of a certain out-of-code high-rise building structure. Under the action of a small earthquake, we used the pkpm software MIDAS/Building to calculate the elastic properties of the building structure. We used the CAD program SATWE to check the bearing capacity and sections of different members during a moderate or strong earthquake, and midasbuilding software to conduct a static elastoplastic analysis of the high-rise building during rare earthquakes. Based on the results of our linear elastic analyses of the structure during earthquakes of different magnitude, we strengthened the design of the main structure, the seismic structure, and the foundation of the building. We present a summary of the proposed seismic strengthening measures and make suggestions for the whole structure, by which the structure can meet the seismic fortification code requirements and be safe and reliable.

Abstract:Based on the experimental results of a three-story ordinary seismic concrete frame, in this paper, we use the capability spectrum method to evaluate the seismic performance of a rectangular frame structure. We obtained the capacity curves from the experimental results, and established the demand curves using the seismic ground motions recorded by stations with different surface characteristics. The assessment results show that the three-story concrete frame can withstand seismic loads in all seismic zones (A, B, C, D, and E) with ground conditions 1 and 2. For ground condition 3, the experimental results of the concrete frame were satisfactory in seismic zones A, B, C, and D. For ground condition 4, the concrete frame was only valid for seismic zones A and B.

Abstract:To ensure the effectiveness of symbolic towers in urban green spaces as regards emergency avoidance, the seismic design of such landscape towers should be further studied. In this work, a seismic design method based on the logistic model is proposed. This method introduces the planning of urban green space used as emergency shelter and the role of function module in the landmark tower of urban green space. The concept of seismic design of urban green space symbolic landscape tower and the application of the logistic model in the seismic design of such towers were analyzed. In addition to the analysis of a simulated engineering example, the seismic performance and seismic design of the symbolic landscape tower of urban green spaces were analyzed. The results showed that the seismic performance of the symbolic landscape tower is good, and the seismic design is reasonable; moreover, the design can meet the requirements of emergency green space and has good landscape effect.

Abstract:Traditional three-dimensional urban planning utilizes three-dimensional technology with computer-generated models. It does not consider the geographical position of cities and cannot guarantee the efficient operation of emergency relief works after earthquakes. In this work, a new model for the planning of urban areas in seismic zones was constructed to address the limitations of traditional three-dimensional urban planning. The principle underlying disaster-prevention zoning and space planning was analyzed by defining urban seismic disaster-prevention space and zoning to provide a basis for urban disaster-prevention space planning. On this basis, the risk assessment method was used to construct the basic model of disaster-prevention space planning for urban areas in seismic zones. Experimental results showed that the designed model presented excellent performance and accounted for the geographical factors of the city. At the same time, the model can guarantee the efficient operation of emergency rescue work in cities after earthquakes.

Abstract:The Great Wall of the Ming Dynasty is an open system that is unified with the environment along the Silk Road. Environmental factors exert considerable influence on the disease development and spatial-temporal evolution of the site. Typical sites with different environmental characteristics were selected for the investigation of the climate characteristics, geological physiognomy, and seismic activity along the Silk Road. The characteristics and spatial distribution laws of various types of diseases, which are affected by various main factors, were identified by referring to historical materials and performing field investigations and laboratory tests in combination with the investigation of environmental characteristics, architectural configurations, and soil properties. The disease evolution mechanism was further revealed by verifying the existence, formation, and development of various diseases and would guide the prevention and monitoring of the formation and development of diseases at the study site. In recent years, site reinforcement and protection projects frequently encountered destructive issues that necessitated repair. A comprehensive protection scheme that combines reinforcement and protection should be designed on the basis of the characteristics and mechanisms of various diseases. Such a scheme is crucial for the long-term preservation of soil sites at the Great Wall of the Ming Dynasty.

Abstract:Active faults are the root causes of earthquakes, so buildings along fault lines experience the most severe damage during earthquakes. Therefore, by adopting a shallow geophysical method to accurately determine the location and distribution range of active faults and implementing effective engineering measures to evade earthquakes, we can greatly reduce earthquake disaster and consequent economic losses. The Kangding-Selaha fault is the main fault in the southeast segment of the Xianshuihe fault zone, with the tectonic condition of strong earthquakes; thus, the seismic risk in the towns passed by the fault cannot be ignored. Because the areas of the new city of Kangding that pass by the Kangding-Selaha fault are in alpine valley regions, such detection areas are subject to inconvenient traffic conditions and narrow working spaces; therefore, to obtain seismic profiles, the detection through shallow seismic reflection must be applied with small trail spacing, small displacement distance, and reception of multiple short arrangements and multiple coverage observations of common reflection points. In this study, shallow seismic detection results are combined with high-density resistivity tomography and seismic and geological survey results of the surface to reveal the spatial distribution, size, and near-surface structure of the Kangding-Selaha fault in the southeast segment of the Xianshuihe fault zone. The Kangding-Selaha fault in the southeastern section of the Xianshuihe fault zone exhibits a left-circle and right-border feather-shaped distribution in the northeast side of the new city of Kangding, and it does not only have a main cross-section. The detection results do not only provide reliable seismological evidence for determining the near-surface tectonic activity of the Kangding-Selaha fault, but also provides reliable fundamental data for seismic risk assessment, earthquake resistance planning and hazard prevention in the new city of Kangding.

Abstract:Sample size determination for strong ground motion inputs is one of the most critical issues in carrying out nonlinear dynamic analyses. Most popular studies about ground motion sample size at home and abroad often ignore or barely consider the reliability of the structural seismic response estimation. In this paper, the reliability-consistent sample size determination method is presented to ensure a certain reliability of structural seismic response estimation. First, the statistical characteristics of structural nonlinear dynamic response under large ground motions sample for a typical reinforced concrete frame building are analyzed to discuss the difference between the maximum and mean values of structural responses. Then, based on the hypothesis testing of structural response probability distribution models, a sample size determination method for strong ground motion inputs based on the reliability-consistent method is proposed. In addition, the impacts of synthesized ground motions and single-period and multi-period spectral-matching methods for generating synthetic strong motions on the sample size demand are discussed to provide a determination method and estimation basis and ensure reliability and allowable error of structural response estimation using small sample size strong ground motions. The results show that distribution models of structural response highly accept the logarithmic extremum distribution and lognormal distribution hypotheses and completely reject the normal distribution hypothesis. This method is suitable for various types of building structures and ground motion intensities in determining ground motion sample size demand, which is very significant as regards seismic performance and the study of seismic design code.

Abstract:Earthquake swarm activities have been occurring in the Xianyou area of Fujian Province since August 2010. The level of seismic activity increased in 2012 and further increased in 2013, when M_L ≥ 3.0 earthquakes were concentrated. Sufficient observation data of these earthquakes were recorded by Fujian digital seismic network. In this study, the sequence of M_L ≥ 1.0 earthquakes are relocated using the P-and S-wave arrival data, and it is found that both the spatial location and focal depth of the earthquake sequence show different distribution characteristics for different periods. Meanwhile, based on the waveform data recorded by Fujian digital seismic network, the focal mechanism solutions and the best focal depths of M_L ≥ 3.5 earthquakes are obtained with the "cut and paste" method. According to the characteristics of earthquake swarm sequence, distribution of hypocenter location and fault activity in the hypocentral region, and the focal mechanism solution, it is concluded that the Xianyou earthquake swarm sequence are tectonic earthquakes caused by reservoir water infiltration and then fault slip, and thus, they are reservoir-induced tectonic earthquakes; in addition, the seismogenic structure is the NW-trending Shicang fault which passes through the reservoir area.

Abstract:Based on the waveform and seismic phase data of the Changdao earthquake swarm from February 14 to September 1, 2017, the inelastic attenuation coefficient of the Changdao area is studied, and the relationship between the average Q value and the frequency f in the Changdao area is Q(f)=363.9f^{1.374 1}. The site responses of stations around Changdao are obtained using the joint conversion of genetic algorithm proposed by Moya, and the source parameters of Changdao earthquake swarm sequence are calculated by the Brune model formula. The results show that there are some correlations between the various source parameters:the seismic moment increases with the local magnitude M_L, and there is a semilogarithmic relationship between the seismic moment and the rupture radius R. The corner frequency f_c decreases with the increase of seismic moment. The stress drop values of the Changdao earthquake sequence are generally small, and the maximum does not exceed 0.9 MPa, which means the overall structural stress in Changdao focal area is low. Considering the changes of source parameters over time, the changes in stress drop of the earthquake swarm is very irregular. Before the occurrence of the M4.1 earthquake, the corner frequency and stress drop both decreased rapidly and immediately increased. This proves that the overall stress in the Changdao focal area increased before the M4.1 earthquake.

Abstract:In this study, we used the seismic strain field as a variable indicating seismic activity. Using natural orthogonal function expansion, we calculated the seismic strain field prior to the Jiuzhaigou, Sichuan M_S7.0 earthquake on August 8, 2017, and extracted anomalous variations in the time factor prior to the earthquake. The calculation results show no obvious mediumor short-term anomalies in the first four time factors of the strain field in the period 1-3 years before the earthquake, with abnormal changes of small amplitude occurring only in the second and fourth time factors before the earthquake. The time factors may be affected by the large amplitude anomalies occurring prior to the 2008 Wenchuan M_S8.0 earthquake and the 2013 Minxian-Zhangxian M_S6.6 earthquake. The spatial contours that correspond with the time factors indicate a dangerous area in the local strain's high value anomaly, which may be medium-and short-term characteristics of the spatial anomalies of the Minxian-Zhangxian M_S6.6 and Jiuzhaigou M_S7.0 earthquakes. Next, we compare the evolution of the spatial anomalies with time before and after the Jiuzhaigou M_S7.0 and two Songpan-Pingwu M_S7.2 earthquakes, and analyze the differences in their abnormal development patterns. Lastly, we describe the mechanism of anomaly formation from the physical perspective by applying the cumulated frequencies of the seismic data.

Abstract:In the process of automatically identifying infrasonic waves in a focal region prior to the occurrence of an earthquake, tripartite array arithmetic has difficulty locating the source of infrasonic waves as it cannot automatically screen and identify a large amount of abnormal-infrasonic-wave data. This leads to low monitoring accuracy and efficiency prior to an earthquake. In this work, we present an automatic method for identifying anomalous infrasonic waves in the cloud computing environment. We constructed a JNS abnormal-infrasonic-wave data acquisition and screening module to scan the access port in real time, and quickly provide feedback regarding abnormal infrasonic data. We use an NDS abnormal-infrasonic-data-sequence detection algorithm to quickly identify a wrong sequence matrix, and accurately retrieve, locate, and lock the abnormal infrasonic wave data. This automatic recognition method can be used to classify anomalous infrasonic waves and determine whether the seismic signal is suspicious. The experimental results show that the proposed method can efficiently and automatically identify abnormal infrasonic signals prior to an earthquake, with a maximum signal classification accuracy of 99.99%, and a maximum average multiple recognition time of only 1.3 min.

Abstract:An early earthquake warning system is one of the most effective ways for seismic hazard mitigation, in which earthquake magnitude estimation is the most important and difficult task. Currently, different empirical models have been used to estimate earthquake magnitudes based on τ_p^max, τ_c, or P_d, which are derived using an initial part of P-waves. Here, rapid magnitude estimation model for the Sichuan region was researched and verified based on three large earthquakes in the Yunnan region in 2014. The result showed that three models based on the three parameters above can effectively be used for magnitude estimation in a short time. As for the database in this study, P_d-4 s model worked best among them and all three models did not underestimate the magnitude of large earthquake events. However, it is currently difficult to obtain the accurate epicentral/hypocentral distance in a short time window. Hence, τ_p^max and τ_c models are recommended for use in the Yunnan earthquake early warning system.

Abstract:A model for the scheduling of emergency logistics resources after earthquakes was designed against the background of big data analysis to address the low efficiency of the traditional resource scheduling model, which is based on the round robin scheduling algorithm. Vehicle and helicopter schedules were established with the purpose of loss minimization and in accordance with the material demand of affected sites and the treatment demand of casualties. In the model, the genetic scheduling algorithm was used to obtain multiple resource scheduling strategies through population initialization. The selection probability of the resource scheduling path was calculated in accordance with the subpopulation fitness value. Experimental results showed that the designed model can guide the efficient dispatching of postearthquake rescue resources.

Abstract:To improve the safety of reconstruction in disaster-stricken areas, a safety management method for post-earthquake reconstruction site based on the ARIO model was proposed. On the basis of dividing the influencing factors of architectural design into direct factors and indirect factors, the ARIO model was introduced into the post-earthquake reconstruction site safety management, and was used to analyze the connection between various industrial technologies and the regional economy during the construction process. The initial data acquisition system, pre-construction safety management system, and safety management system during construction were designed and established. The ARIO model was combined with VR, so that the builders can complete the virtual construction in a virtual roaming system during the operation of each system and master relevant information such as construction period, process, and utilized equipment. Then the assisted experts can provide detailed guidance for the safe and systematic management of the reconstruction site after earthquake occurrence. The experimental results showed that the safety factor of this method exceeds that of the current method. Moreover, the method is highly scientific and robust.

Abstract:Traditionally, inertial navigation sensor technology, based on signal sensing technology, has been used to locate search-and-rescue personnel by combining the distance they have moved with their angle of direction. This method is easily affected by poor weather conditions and partial occlusion, and the resulting search-and-rescue efficiency and accuracy are low. In this paper, we propose a new search-and-rescue method based on visual imagery for victims in earthquake areas. Initial visual images of the seismic area are collected by image acquisition equipment, and the wavelet denoising method is used to reduce the noise and improve the discernibility of the images. Then, after noise reduction, the visual image features of people in the seismic area are extracted using the color contrast method, and compared with the original image features of the seismic area, to obtain candidate images of rescuers in the seismic area. According to these candidate images, a Kalman-filter tracking algorithm and a mean-shift tracking algorithm are used to track search-and-rescue personnel in complicated seismic areas during poor weather conditions and partial occlusion, respectively. The experimental results show that the recall rate of the proposed method is above 98.5%, the average accuracy is about 98%, and the average search-and-rescue time is about 23 s. These results indicate that the proposed method can efficiently and accurately locate victims for search-and-rescue operations in seismic areas.

Abstract:To solve the problems of the traditional gridding method, i.e., its relatively large computational error and low computational efficiency, in this work, we propose a new GIS-based method that uses DEM data, land data, and basic geographic data to extract various influence factors such as topography and landform.Using the sum of the construction area and land-use classification data, we establish a multiple linear regression model and obtain the distribution of buildings on a 50-mm grid scale.We then determine the correlation between the POI data and the building space to establish a spatial distribution model for post-earthquake repaired buildings.The experimental results show that the proposed method effectively reduces calculation error and improves calculation efficiency.

Abstract:Today, the PID controller is used to control the servo system of unmanned rescue vehicles, but it has a number of problems, i.e., the trajectory tracking accuracy is not high, the error control performance is poor, and the flexibility, stability, and safety performance are not good.In this work, we propose and design a servo system for unmanned rescue vehicles based on the BP-neural-network-tuning PID controller.Then, we establish a drive model for the servo control system of the unmanned rescue vehicle in sudden earthquake disasters.We obtained the PID control law based on the control deviation and realized system control by adjusting the parameters of the PID controller.On this basis, we constructed a PID controller based on BP-neural-network-tuning, and use the gradient descent method to correct the weighting coefficient of the controller.By adjusting the weighting coefficient of the BP neural network online, the controller can be adaptively adjusted to control an unmanned rescue vehicle in sudden earthquake disasters.The experimental results show that the servo system of the designed unmanned rescue vehicle based on a BP-neural-network-tuning PID controller can effectively improve the trajectory tracking accuracy, improve flexibility, and ensure the safety of the driver and smooth operation of the vehicle.

Abstract:There are many factors involved in a post-earthquake building fire. The traditional assessment model ignores the influence of building cross-sectional temperature change and building deformation degree, which leads to low accuracy of evaluation. To solve this problem, a fire risk assessment model of post-earthquake buildings was established the by "fuzzy mathematics" method. On the basis of establishing the judgment matrix, the weight of the evaluation model was obtained and the membership matrix determined. By determining the factor set and comment set for the assessment of cross-sectional temperature change after an earthquake fire, single factor evaluation was carried out to realize the first-grade fuzzy evaluation. The first-grade evaluation result was considered as the single factor of second-grade evaluation. The buildings' fire risk assessment post-earthquake was then completed along with the with the fuzzy mathematical analysis. In the experiment, the temperature change and deformation degree of the cross section of the building beam was taken as the index to evaluate the fire risk of the post-earthquake building. The experimental results showed that, when using the proposed model to assess the fire risk, if the post-earthquake building is on fire, the higher the beam section's temperature and the greater the deformation degree, the higher the overall fire risk. The evaluation accuracy of the proposed model was high.

Abstract:Using the stochastic state-space model and expectation maximization (EM) algorithm, operational modal analysis for civil structures is performed in this paper. The EM algorithm is a process to obtain the maximum likelihood estimate of the model by updating the model parameters iteratively. The modal parameters could be obtained from the identified parameters of the state-space model. In this study, the square-root version of the Kalman filtering method is applied to improve the computational robustness of the EM algorithm. Considering the correlation between input and measurement noises in the state-space model, an extended parameterization for the state-space model is established. The performances of the stochastic subspace identification (SSI) method, the EM algorithm without considering the noise correlation, and the proposed EM algorithm considering the noise correlation, are comparatively studied, and the results show that the EM algorithm considering the noise correlation is more accurate than that without considering the correlation. In addition, the proposed EM algorithm performs better than the SSI method in the case of short-length data.

Abstract:In field data observation systems for artificial seismic sounding, seismic waves are generated by artificial explosion. Seismometers deployed along the surveying line are used to collect the seismic phase information from the crust and upper mantle. This information helps understand the fine structure of the crust and upper mantle, the relationship between shallow and deep structures, and the spatial distribution characteristics of seismogenic structures. Information on these topics aids the study of the evolution and dynamic processes of the lithosphere. It is critical to determine the accurate explosion trigger time and geographical position of the explosion spot to meet the needs of the subsequent seismic data processing. In this study, a new GPS synchronization clock device based on MCU AT89C5115 is designed. This paper introduces the hardware structure and implementation method of the firmware program of the device. The device has the functions of human-machine interaction control and data communication. Indoor and outdoor test results indicate that the clock device is stable and reliable and can meet the needs of artificial seismic field work.

Abstract:The traditional fault detection method based on time-series data mining cannot perform sensitivity analyses of the high-sensitivity electronic earthquake early-warning device, and its fault detection rate is low. In this paper, we propose a new fault detection method for the high-sensitivity electronic earthquake warning device. Based on the device structure, we constructed a mechanical model using a mass block, hinge, and extended beam to obtain the sensitivity expression of the device. According to this expression, we established a multi-signal model correlation matrix, and obtained the fault source cost of the fault preemption probability. We adopted an improved multi-signal model detection method based on the fault probability of the fault mode in detecting faults of the electronic earthquake warning device. The experimental results show that the fault detection rates of the two indicators G and I in the TE process of the electronic earthquake warning device are 0.989 and 0.905, respectively, the fault detection time of the PL process is 180 s, and the fault detection rate is 0.412 8. These values are all higher than those obtained by the traditional fault detection method based on time-series data mining, which shows that the proposed method has higher fault detection performance.

Abstract: