Abstract:Steel frames not only have the advantages of being light weight，and high strength but also are corrosion resistant and fireproof，so steel is widely used for industrial construction.Unfortunately，research on corrosion mechanisms and measures of corrosion protection were mainly aimed at the timber level and based on experiments.Due to differences in test conditions，test methods and other factors，conclusions from these experiments were highly variable and empirical formulas were difficult to utilize.In addition，research aimed at component-level corrosion was also not yet clear，so uniform corrosion is often assumed for convenience.For example，some simply reported weakened cross-section members and considered material deterioration to analyze structural performance. In this paper，we consider the seismic performance of overall structure in different service times.Material deterioration and non-uniform corrosion were accounted for in column and beam cross-sections.Steel corrosion caused the deterioration of seismic performance and stiffness for structures.When steel frame structures survive earthquakes，it does not guarantee that the structures will survive one that reaches the design capacity at a later service time.Therefore，when evaluating the seismic performance of steel frame structures in different service times，we must account for the increased seismic risks caused by steel corrosion over time.Changes in seismic performance of structures over different service times were examined in this paper. The deterioration of elastic modulus and steel yield strength were evaluated using existing empirical formulas. At the same time，the thickness variation of the column and beam cross sections in steel frame structures was accounted for by using findings from related research.Different methods including IDA，pushover，and Monte Carlo were combined together to estimate values for different limit states in a probabilistic seismic capacity model. In this paper，the maximum drift angle was taken as the damage index. The statistical parameters of the probabilistic seismic capacity model were estimated through pushover analysis，while the relationship of probabilistic seismic demand was obtained by IDA analysis for random structure samples and different service times.Seismic fragility surfaces of steel-frame structures were obtained in different limit state and different service time （0 year，15 years， 30 years，45 years，and 60 years）. Finally, a case study of a 15-floor steel-frame structure was adopted to illustrate the change in structure fragility that may occur as a result of corrosion. Seismo-structure software and finite-element models were used to test different service times of the structure. Pushover and IDA analysis were then used to calculate values of different limit states in a probabilistic seismic capacity model and the relationships of probabilistic seismic demand models，respectively，over different service times. These achievements would provide theoretical support for the life-cycle design of steel frame structures，operation and management，and especially seismic hazard assessment of existing steel frame structures.

Abstract:Movement of the ground is the key factor in predicting structure deformation.Particularly，for prediction of liquefied ground，large deformation may destroy its superstructure even for horizontal ground.This paper presents the behavior of liquefied silt soil on the basis of lab tests.The post-liquefaction stress and strain of silt was evaluated by test results.The possibility of triggering silt liquefaction and post-liquefaction has been documented by previous studies and historical cases.The behavior of silt differed from sand in some aspects such as pore water pressure dissipation.A series of monotonic tests of liquefied silts was performed using special triaxial apparatus in which the shear strength and large deformation were evaluated for silt ground.The isotropic consolidation samples applied various effective confining pressures for different initial void ratio samples.Cyclic loading was then applied to the samples in undrained conditions. The samples were examined from initial liquefaction to the specified level of liquefaction.The undrained monotonic triaxial compression tests，known as post-liquefaction tests， were then performed on the liquefied silts. Undrained shear strength，pore water pressure，and axial strain were automatically recorded at each stage to determine the shear strength behavior post-liquefaction.In addition，large deformation was evaluated from the relationship of the stress and strain of post liquefaction.The liquefied silt behaved as dilative soil during the post-liquefaction stage.The soil resembled fluid with nearly zero effective stress.The axial strain increased up to 3% at nearly zero effective stress，after which time the pore water pressure decreased and the effective stress began to increase.The increasing axial strain was associated with nearly zero effective stress at the beginning of post-liquefaction. It is noteworthy that soil experienced perfect plastic deformation during the zero effective stress stage. Soil particles lost contact when initial liquefaction occurred during cyclic loading.The condition at the end of cyclic loading was the initial condition for the post liquefaction tests.Therefore，the soil particles with no contact showed nearly zero effective stress.The soil particles regained contact with each other with the dissipation of pore water pressure，and the soil strength also began to increase. It was demonstrated that the initial effective confining pressure and initial void ratio had a great effect on the undrained shear strength of the liquefied silts.Steady shear strength was reached as pore water pressure dissipated.A linear relationship was noted between post-liquefaction steady shear strength and initial confining pressure.The shear strength of the liquefied silt was larger than that with a smaller initial void ratio.

Abstract:Earthquakes are among the most serious natural disasters. The causes of earthquake are very complex，with trigger factors covering many fields of science.Scientists have been attempting to develop approaches for earthquake prediction for decades，with the aims being to define processes involved in earthquakes and to minimize the losses caused by earthquake disasters.Therefore，earthquake prediction has become an active area of research.Thus far，accurate and reliable earthquake prediction is still not possible，worldwide.The fundamental reason is that we have not fully mastered the mechanism，development，and occurrence processes.Fracture of materials acted on by cycling load is called fatigue.The damage process of materials under dynamic loading is known as fatigue process.The damage process of fatigue consists of initiation of cracks and rapid expansion of the cracks.The strata bear a cycling load due to the rotation of the earth and other seasonal factors.The crack of strata often appears due to damage process of fatigue under a variety of internal and external periodic dynamic loads.The damage process also consists of initiation cracks，confluence of cracks and expansion of cracks.This paper follows the theory of fatigue damage and the calculation method of dynamic signal fatigue damage energy.Fatigue failures are one of the most common failure models when the materials are burdened by cyclic loading.Furthermore，it is well known that nearly 80% of destruction of materials is due to fatigue.A mathematic calculation model of damage energy is conducted in this paper based on system analysis theory.With the model，the damage energy during the fatigue process can be calculated rapidly using a signal.The processes of fatigue failure are evaluated by this quantitative research.The results obtained in this paper will improve our understanding of seismic fatigue.We analyzed the seismic dynamic signals recorded at Putian seismic station in Fujian on August，2013 using theory of fatigue damage.A series of earthquakes occurred in August 2013 in the Putian area，with the Putian monitoring station being about 30 km from the epicenter. Signals corresponding to a series of earthquakes were acquired by the Putian station on a time interval of one hundredth of a second.The bearing capacity of rock fatigue damage was calculated，and shows that the calculated bearing rock fatigue damage energy has the following rules：（1） the fatigue damage energy of a rock formation changes with time.（2） Fatigue damage energy is circular before the earthquake，and the cycle for fatigue damage energy is one day （24 hours）.（3） the most obvious changes of fatigue damage energy occurred between 21:00 and 06:00 and between 12:00 and 15:00 Beijing time. （4） Earthquake magnitude was higher between 12:00 and 15:00，while fatigue damage energy was also higher before the earthquake.

Abstract:With the rapid growth of urban population in recent years，traffic problems have become increasingly serious.Subways offer an effective means for solve such issues.It is worth noting that many underground structures are located in seismically active areas；therefore，seismic design and reliable assessment of underground structures must be conducted. However，many studies on earthquakes have indicated that underground structures are not as safe once believed and can collapse under dynamic loadings such as earthquake loading.Therefore，seismic design and reliable assessment of underground structures has been an important subject；however，research on seismic areas of underground structure in our country is insufficient.Particularly in areas with soft soil，where the situation is more complex，it must be resolved that the underground structures affected by seismic wave are maintained as safe and reliable.Thus，it is necessary to study the analysis theory and design method of underground structures in the soft soil areas in Tianjin by combining by including underground engineering structure characteristics and soil conditions.According to the actual engineering conditions of the typical subway station structure in Tianjin metro line 3，a model for soft soil station structures has been developed by using ANSYS software.The numerical analysis on the dynamic responses of this model under dynamic loading，Tianjin seismic wave，Taft seismic wave，and artificial seismic wave were conducted.Under different loading conditions，the internal force and deformation of main component were analyzed，particularly for of the center pillar. The displacement amplitudes of this station structure under various seismic waves are approximate and can conform to the standard requirements.The maximums of amplitudes were also determined.The internal force under the Tianjin seismic wave is the maximum，and the seismic vulnerability is located in the bottom of middle column.Therefore，these research results can be used for the seismic design of subway station structures in the soft soil area of Tianjin.

Abstract:Hollow piers are widely applied on railway bridges.In high intensity seismic regions，hollow piers and solid piers differ greatly in the arrangement of the longitudinal reinforcements and stirrups.In addition，plastic hinge mechanisms and positions of hollow piers are very different from those of solid piers.Experiments must be completed to examine solid piers on plastic hinges and then the findings applied to hollow piers.In this paper，methods of testing and numerical analysis are introduced and used to study the plastic hinge’s mechanism and position of hollow piers.Firstly，based on the hollow piers on the Dali Ruili railway，three large-scale models were made to study reasonable reinforcement arrangement，seismic damage model，and plastic hinge zone length by using pseudo-static test methods.Pseudo static test methods are the most widely used test methods for studying structural or component performances.This method maximizes the number of specimens and provides an abundance of information such as the bearing capacity，stiffness, deformation capacity，energy dissipation，and damage characteristics.From the scale model，hysteresis loop，plastic hinge zone length，and failure characteristics of hollow piers were obtained under the cyclic horizontal loads.The results show that under the design reinforcement arrangement，the model presents ductile failure whose characteristics are concrete crushing with obvious plastic hinge region.In addition，the plastic hinge zone length is similar to the dimension of the pier section （along the stress direction） at the bottom of the pier.Secondly，a fiber element model was made by using the software Opensees.During the finite element analysis，no constraint model was used for protective layer of concrete and Mander model was used for core concrete.Then，a monotonic loading skeleton curve and hysteresis loop were obtained through numerical modeling.Finally，after comparing the model results and test hysteresis curves，it was shown that numerical results were consistent with results obtained experimentally.

Abstract:There are many existing masonry structures in China.This structural material has low intensity and poor ductility.Substandard design，nonstandard construction，aging，and higher performance requirements mean that the safety of existing masonry structures cannot be guaranteed.The large cost of rebuilding and the huge impact on daily life and the environment make performance based seismic strengthening studies of existing masonry structures necessary.This article discusses the architectural seismic performance，seismic time history analysis，structural strengthening，and strength optimum of existing masonry structures，thus supplying reliable technical literature for practical application in engineering and revision of the related criterion.Several issues are discussed.（1） Some issues in the detection，evaluation，and strengthening of existing masonry structures are summarized，the deficits and contradictions in the detection，evaluation，and strengthening of existing masonry structures in terms of the current specifications and software for calculation are analyzed，and a homologous solution is proposed.（2） In agreement with the earthquake levels for new structures，earthquake levels for structures with a continuous seismic working life of 30 or 40 years for conditions of frequent earthquakes，anti-seismic fortification earthquake，and rare earthquakes are proposed.The factors affecting the anti seismic capability level of buildings，such as structural importance，social impact，casualties，structural damage，in house facility damage，and direct and indirect economic loss are also considered.Every factor is graded and its anti seismic capability level is quantized.The structural performance objectives are serialized，and a relation between the capability level value and the limiting value of the story drift angles is proposed.（3） On the basis of the site condition and structural condition，screen strong shock’s recorded wave and artificial fitting wave，Tianjin seismic waves，Qian’an seismic waves and artificial seismic wave can be in better agreement with the physical condition.In line with local earthquake level，adjust peak acceleration of Tianjin seismic waves，Qian'an seismic waves and artificial seismic wave in frequent earthquake，anti-seismic fortification earthquake and rare earthquake.Analyze the effective duration，and obtain proper seismic wave time histories acceleration.（4） To simplify the practical engineering and establish a finite element model，dynamic and time historical analysis is carried out for two structures using worked Tianjin seismic waves，Qian’an seismic waves and artificial seismic waves.The corresponding maximum displacements of three panel points for every layer of the structures are measured. The average value is used to reflect the displacement of each floor，and the maximum story drift angle is compared with the performance objective.The results show that the anti seismic performance requirements are not satisfied in either structure，and they should be strengthened.The results of strengthening are：（1） the location of the maximum displacement angle of a floor moves down after strengthening；（2） the reinforcement effect is clearer in the superstratum than in the substratum；（3） the presence of ring beams and constructional columns has a greater effect on the anti-seismic properties；the sectional dimensions of ring beams and constructional columns have less of an effect on the anti seismic properties；（4） the reinforcement effect is determined by the seismic waves.Different results are obtained for the same reinforcement scheme for different seismic waves：（5） the anti seismic properties will not be improved by all strengthening methods. A reasonable strengthening scheme must be selected，or the effect will be counterproductive.

Abstract:The structures of cable-stayed bridges are quite different from that of continuous beam bridge，so their vibration characteristics and seismic response are also different.A（64+115+115 +64）m three tower and double cable plane cable-stayed bridge was chosen as the analysis example. At pier 2# of this bridge,the tower，beam，and pier are rigidly connected together.At the other movable pier，the tower and beam are rigidly connected together，and separated with the pier.The bridge has a seismic intensity protection rating of seven.To analyze the seismic response and evaluate the seismic performance of a cable-stayed bridge，a whole bridge space dynamic calculation model was established using the MIDAS program.The spatial beam finite-element model was used to simulate the tower，pier，and beam.The cable was simulated by the tension-only spatial truss element which also took the geometrical non-linearity into account.The bearings were considered as the ideal constraint according to the actual constraint conditions.The SSI effect was also taken into account by the application of a soil spring both in the translation and rotation directions.Natural vibration characteristics were analyzed；therefore，the dynamic characteristics and vibration mode of cable-stayed bridges with multi-span and low towers were well understood.The first five vibration modes including the vibration shape and the self vibration period were extracted.The first vibration shape is an anti-symmetric vertical bending of the beam，which is similar to the continuous beam bridge.However, they differ in the vibration shape that includes the vibration of the tower and cable compared with continuous beam bridge.For low-level earthquakes，the response spectrum method was adopted to analyze the elastic response in horizontal and transverse directions.The first 300 vibration modes were used in the spectrum method，and the CQC method was used in combination with seismic response in each vibration mode.The bending-moment and shear-force diagrams of the bridge structure were drawn in horizontal and transverse directions，whereby，the results show that the longitudinal earthquake response of fixed pier 2# was the biggest and dominates the seismic design.Under low-level earthquake ground motion，the bridge is in an elastic condition，that is，the pier and tower are in an elastic state and can return to their original shape after the low-level earthquake.Under low-level earthquake ground motion，the allowable stress method was adopted in the design.The stress was calculated in accordance with the eccentric compression member and results show that the bridge can meet the required specifications to achieve performance level I.For high-level earthquake ground motion，the non-linear time-history analysis method was adopted to analyze the elastic-plastic response.The maximum plastic rotation angle should be limited within a safe range.To acquire the maximum plastic rotation angle，the artificial seismic waves under high-level earthquake conditions were input into the model，and results showed that the plastic deformation capacity can meet the required specifications and also have a degree of safety reserves.Under high level earthquake ground motion，the bridge may suffer great damage without overall collapse，which can play a role under limited traffic and after repairs；it can achieve performance level III.

Abstract:Supplemental damping is becoming an increasingly tested and reliable seismic design strategy，which has resulted in the evolution of building guidelines to include supplemental damped structures.The usage of supplemental viscous dampers to dissipate energy and reduce building response to dynamic inputs is gaining worldwide acceptance. The concept of supplemental dampers added to a structure is such that the dampers，rather than the structure itself，absorb much of the energy input to the structure from a transient.The placement of dampers is a critical design concern because the distribution of damping may significantly affect a building’s dynamic response and the necessary damping cost.However，current building codes and guidelines have not yet prescribed a particular method for optimal placement of dampers.Although the 2003 National Earthquake Hazards Reduction Program （NEHRP） provisions offers a methodology for determining the total damping value corresponding to a desired effective damping ratio，it does not address the optimal distribution of the dampers.This paper presents an application of viscous dampers in a space structure to suppress anticipated earthquake action.The northwestern Chinese region is an area affected by many earthquakes；therefore，seismic retrofitting of existing buildings presents many difficulties in this region. Any intervention in their structural system should neither violate their forms nor create dramatic changes in their structural behaviors.To study the vibration control of large span space structures with viscous dampers，dynamic time history analyses were performed for a gymnasium building subjected to three dimensional earthquake ground motions.To evaluate the seismic performance of the space structures，three dimensional mathematical models were prepared by using FEA ANSYS software.The models incorporated geometric （P-Δ），material （member yielding），and viscous dampers （axial force axial displacement hysteresis） nonlinearity.Seismic masses were calculated on the basis of the dead plus one second live load combination.The finite element analysis results were used to investigate the response of the building and to determine the extent of nonlinear response in members.The targets of the vibration control were to reduce horizontal displacement and member forces for the roof structure，as well as storey displacement and storey shearing force for lower frame structures.The results indicate that the seismic response reduction of the roof structure was obvious under various seismic waves，although the effect of vibration control of the lower frame structure was sensitive to earthquake frequency characteristics.The use of viscous dampers can dramatically reduce displacements and internal forces of the upper and lower structures various different seismic intensities.Uniform placement of the viscous dampers showed better vibration control performance when compared with centralized placement on the roof of the space structure.Moreover，the mode of vibration was complex for space structures，and interaction between the upper and lower structures needs to be considered in vibration reduction analysis because of its great effect on seismic response of space structures.The viscous damper system proves to be a very effective method for reducing seismic response.These research results will provide a useful reference for practical application of viscous dampers in super long span space structures.

Abstract:Poisson’s ratio was characterized for shallow stratum in Tianjin from more than ten borehole logs collected during the period of the“10th five-year-plan”.Associated borehole histograms and laboratory test documents were also compiled for discussion of influencing factors such as the soil moisture，wet density，and porosity ratio. Based on the borehole logging data，we developed a scatter graph of Poisson’s ratio versus depth and fit a curve to the data to represent shear wave velocity and compression wave velocity. The graph shows that the Poisson’s ratio changes by three stages as a function of depth.In the first stage，in the range of 0 to 5 m，it increases rapidly from 0.420 near the surface to 0.495 at a depth of 5 m. Fluctuation in Poisson’s ratio may result from stiff artificial soil cover of different thicknesses that formed for thousands of years of natural processes and human activities near earth surface. In the second stage，in the range of 5 to 20 m，it tends to be stable and the value mostly remains at the level of 0.495，where the stratum mainly consists of soft，saturated，and plastic mucky stratum. In the last stage，in the range of 20 to 200 m，it slowly decreases but shows considerable discreteness and some kind of linear feature is revealed by the fitting correlation coefficient.This decrease in the last stage may be the result of changes in soil lithology，soil sedimentary environment，and soil provenance at greater depths.Many cycles of transgression and regression occurred in Tianjin during the Quaternary period，so the shallow stratum mainly consists of continental facies，marine facies，and marine continental mixed facies.These varying depositional settings caused great changes of lithology，and sedimentary environment in Tianjin. Moreover，the migrations of the Yellow River and Haihe River also influenced the sediment mineral compositions greatly：In summary，the sedimentary environment and evolution mechanism strongly affected Poisson’s ratio of the shallow stratum.Factors influencing Poisson’s ratio in the sediment were examining by selecting two typical boreholes and developing a Poisson’s ratio curve and associated histogram.Additional data including curves of soil moisture，porosity ratio，and wet density were all displayed in one figure together.It shows that the Poisson’s ratio is positively correlated with soil moisture and porosity ratio and negatively correlated with soil wet density.The form of Poisson’s curve is strikingly similar with that of soil moisture and porosity ratio curves and is opposite to that of a wet density curve.By comparing soil moisture，wet density or solid mineral components，it is easy to see that soil moisture has greater effect than wet density.In other words，soil moisture is may be the key parameter influencing the soil’s Poisson ratio.Further，comparing the curve of Poisson’s ratio and related borehole histogram, we can see that the changes of soil lithology at greater depths indicate a change of Poisson’s ratio. However，it is difficult to obtain Poisson’s ratio accurately based on soil lithology because the characteristics of stratum are very complicated and strongly regional.Because of the great number of factors contributing to Poisson’s ratio，further examination of the factors is necessary especially for application in a different geologic setting.

Abstract:Rainfall is one external，dynamic factor that may induce landslide formation.Different rainfall intensities and rainfall durations affect the dynamic development of the seepage field，which may lead to a change in landslide stability.Research is limited regarding rainfall effects on landslide stability；therefore，a reliable basis for the deformation failure mechanism and mode analysis under heavy rainfall cannot be provided.This article examines a case study of the Shihuixi landslide in the Tongren region by applying a combination of different rainfall intensities and rainfall durations.Shihuixi landslide stability is evaluated using saturated unsaturated seepage theory and limit equilibrium theory and the SLOPE/W module.The research shows that under different rainfall intensity conditions，landslide stability deteriorated sharply after the first day of rain.Increases in rainfall intensity cause the stability coefficient to decrease rapidly，hence，significantly reducing landslide stability.When the rainfall intensity was 100 mm/d，landslide stability was basically close to whole sliding state.When rainfall duration increases，the landslide stability deteriorates sharply and the stability coefficient rapidly decreases.Landslide stability deteriorated significantly，when the rainfall duration was 2 days or 3 days.

Abstract:Xinjiang，the northeastern margin of Qinghai-Xizang block，Sichuan-Yunnan，and North China are main tectonic and seismic regions of China. Fortunately，these regions contain dense network of GPS stations that can be used to study strain accumulation.In this paper，strain accumulations in these regions of the Chinese mainland are studied over the time periods of 2004-2007，2009-2011，and 2009-2012. We use GPS data and horizontal velocity fields that are aided by inversion of negative dislocation.Dynamic evolution features of strain accumulation at related fractures are discussed，together with abnormal status before the Lushan earthquake，and possible variation of strain accumulation after the Wenchuan and Japan great earthquakes.The results indicate that：（1） For one to several years，in North China after the Japan MS9.0 huge earthquake and the Sichuan-Yunnan area after the Wenchuan-Yushu great earthquakes，the strain accumulation rate decreased for most tectonic faults，which suggests that there is a possibility of adjustment influence after great earthquakes.It the West Qinling tectonic region in the southeastern Gansu，for a certain period after the Wenchuan earthquake，the strain accumulation rate increased，possibly showing influence of the Wenchuan great earthquake to some degree，and corresponding with the occurrence of the Minxian-Zhangxian MS6.6 earthquake in July 2013.After the Wenchuan earthquake，the southern segment of Longmenshan fault continued to accumulate strain with a slight increase in strain accumulation rate observed in 2012.This may reflect background information of strong earthquake preparation before the Lushan great earthquake to some degree.（2） Higher energy accumulation background exists at the west segment of the Southern Tianshan fracture and in the region where it meets the Northern margin fault of Western Kunlun.This same phenomenon is observed where the Anninghe fault meets the Zemuhe fault，in the middle segment of Honghe fracture，in the western segment of Qilianshan fracture，and the boundary between Shanxi，Hebei，and Neimeng.

Abstract:It is difficult to quantitatively calculate or predict earthquakes in advance；however，in areas of high density data regarding earth characteristics and monitoring prediction may be possible.This paper presents an earthquake prediction model that is based on the Particle Swarm Optimization Algorithm.The inputs of this model consist of 14 items，which are abnormal index data，they include banding，dead zone，short leveling，and so on，and the output is the classification of the earthquake magnitude.This model sets the average distance of cluster as the evaluation function of Particle Swarm Optimization Algorithm，explores and analyzes the relationships between pre earthquake precursor data and earthquake magnitude.The specific steps of the algorithm are stated as follows：Firstly，we normalize the original data of earthquake cases，which eliminates the dimensional effect；Secondly，we initialize the model parameters using reasonable values from earthquake cases；Thirdly，we pick up the speed through applying the Particle Swarm Optimization Algorithm and design the update strategy；and Finally，we design the evaluation function.If the algorithm satisfies the evaluation function，the algorithm needs to be stopped，and output the optimal solution；otherwise，it needs to turn to the third step.To verify and prove the correctness and efficiency of earthquake forecasting that is based on Particle Swarm Optimization Algorithm，an experiment in the environment of Matlab 2007a is conducted and a comparison with the classical k means Clustering Algorithm is made.The experimental data are divided into 3 categories，among which，Category 1 represents Magnitude 5~6 of earthquake，Category 2 represents Magnitude 6~7 of earthquake，and Category 3 represents Magnitude 7 and greater earthquakes.As for the accuracy rate，the overall forecast accuracy rate of k-means Algorithm is only 73.3 %；however，Particle Swarm Optimization Algorithm can increase the accuracy rate up to 83.3 %. To analyze the stability of the algorithm and the complexity of time，the results of five experiments were randomly selected to calculate the average distance among clusters and the processing time. Through analysis，we show that the processing time of the Particle Swarm Optimization Algorithm is slightly longer than the processing time for k means Algorithm.The average distance using Particle Swarm Optimization Algorithm to conduct cluster is smaller than that of k means Algorithm，this indicates that Particle Swarm Optimization Algorithm has an advantage of better stability than the classical k means Clustering Algorithm.The experimental results indicate that，this model can effectively predict the earthquake magnitude in accordance with the earthquake precursor data.Compared with the traditional cluster k means algorithm model，Particle Swarm Optimization Algorithm is much stronger，and the forecast accuracy is much higher.The research and analysis of the example of historical seismic data indicate that the model suggested in this paper makes full use of the highly robust and flexible Particle Swarm Optimization Algorithm as well as the coordination strategy of swarm intelligence.This represents a promising approach to improve the efficiency of earthquake forecast.

Abstract:Fractal （correlation）dimension and b-value are determined from seismic catalog recorded in Mongolia and its surrounding area.The spatial correlation of 1.56 is indicative of more or less clustered events in the region, while a b-value of 0.962 implies a highly active seismic region.A detailed study of the frequency-magnitude distribution and fractal dimension as a function of depth is also made.The results suggest structural variability at different depth levels in the Mongolia seismic zone that reflects highly heterogeneous and differential stress distribution in the region. Our result also shows that positive is the relationship between the b-value of the Gutenberg-Richter relation and the fractal dimension D of earthquakes in Mongolia region.

Abstract:Magnitude of an earthquake is an important measure used to compare earthquakes in space and time.There are some problems with the current magnitude scales，ML，MS，mB and mb，including uncertainty in the physical meaning and determination results are inconsistent.It is widely recognized that the moment magnitude is an absolute standard measurement of mechanics and may be an ideal magnitude scale because it is not a magnitude of saturation but stabilization.This article briefly demonstrates some progress achieved by Chinese scholars in comparing disparate magnitude scales used by the China Earthquake Networks Center （CENC） and major foreign organizations.In addition，conversional relationships between various earthquake magnitude scales are explored.We will present the comparison between the moment magnitudes for various earthquake magnitude scales and foreign standards，for example，when 6.5≤M≤7.6，mB≈MW；when 5.2≤M≤8.0，MS≈MW；when 4.2≤M≤7.0，ML≈MW；when 4.0≤M≤6.0，and mb≈MW. In each range above，the deviation between MW and mB，and between ML andMS is less than or equal to 0.2. After derivation，the comparison of moment magnitudes and earthquake magnitude scales in our regular standards are as follows：when 4.5≤M≤5.8，mB≈MW；when 4.5≤M≤7.5，mb≈MW；when 4.5≤M≤7.0，ML≈MW；And MS≈MW；MS7=MW.In the magnitude ranges above，MW deviated from mb and MS by less than or equal to 0.2，was equal to MS7；and deviated from ML by 0.22. It is suitable for all kinds of magnitude scale ranges，whereby generally：ML is applied to magnitude 1.0~5.9 earthquakes；mB is applied to magnitude 3.5~6.5 earthquakes；mB is applied to magnitude 4.5~7.5 earthquakes；MS is applied to magnitude 6.0~8.0 earthquakes; and MW is applied to all earthquake magnitudes.It is also considered a priority to catalogue conversions from the different magnitude scales.The process of earthquake rupture is complicated，between the same rupture scales （the same M0），and the altitude source spectra of some frequency are very different because of the different stress field background，rupture velocity，and rupture pattern.It is shown that there is a big difference between magnitude scales because of the limit used by different countries，different geographical conditions， instrumentation，and formula for computing magnitude.The conversion relationship between different magnitude scales is difficult to define.This article showed that the conversion formula of moment magnitude was inferred further using empirical formulas based on prior studies and not direct conversion between moment magnitude and other magnitude scales. The approach used here could be applied to earthquake forecasting.The next step to carry out the work is that establishing direct experience relation according to the thought from Mr.Chen Peisheng: establishing direct relation formula between ML，MS，mB，mb，and MW so the results may be more reliable.In addition，it would be necessary to investigate a number of parameters such as seismic moment of great earthquake，small earthquake，shallow （-focus） earthquake，and bathyseism.Seeking empirical relationships between logs M0，ML，MS， and mb is a good approach.

Abstract:The Wenchuan MS8.0 earthquake occurred on the Longmenshan fault zone，which is a convergent zone separating the Sichuan basin from the Bayan Har block.In this paper，we analyze the latest slip model inverted from geodetic data.We find that the thrust slip distributions along the fault depth in different segments of the Wenchuan MS8.0 earthquake have common characteristics，although there are apparent complexities and differences in the Yingxiu segment，the Hongkou segment and the Beichuan segment.We decompose the thrust slip into three segments.The total amount of slip in the three segments can be decomposed into three partial slides.The first partial slide is a bottom slide distributed at a starting depth of around 17 or 18 km，with the depth range of the slide being about 2 km.The second partial slide is an intermediate slide distributed at a starting depth of around 11 km，with the depth range of the slide being about 10 km.The third slide is the remaining slide after removing the previous two partial slides from the total slip amount.The first partial slide and the second partial slide may be caused by some local rupture energy，and probably have little to do with the macroscopic mechanical environment.Thus，we take the third slide as the typical thrust slip of the three segments to compare with the other segments.After the above decompositions，the thrust-slip distributions in the Yingxiu segment，the Hongkou segment and the Beichuan segment seem to show a similar shape with the other segments.That means the thrust-slip distributions along the fault depth in the Wenchuan MS8.0 earthquake exhibit almost the same shape and follow the strike of the fault within the 200 km range from Yingxiu to Nanba，which may lead to the consistency.We construct a plane-strain numerical model using a finite-element method to examine the potential strike-slip scenarios.Our finite-element model takes the same geometry as used in the inversion of the slip model，with the exception of using a spline to imitate the seismogenic fault.Faults in the Longmenshan fault zone have steep slope at the shallow part and gentle slope at the deep part，and the dip angles of the faults gradually become smaller with depth. Therefore，a spline with two end points having fixed tangential angles is more realistic and reasonable.The southeast boundary of the model is constrained to move only up and down.Pressure is applied to the northwest boundary of the model to simulate the force exerted by the Bayan Har block on the Longmenshan fault zone.Results show that the slip distribution shapes of the fault model are closely related to the force exerted on the northwest boundary.Under the appropriate force，ruptures on the fault model would appear to have the same slip distribution shape as shown in the Wenchuan MS8.0 earthquake.Thus we conclude that the shape consistency of the thrust-slip distribution is probably due to the consistency of the shallow structures and the macroscopic mechanical environment within the 200 km range following the strike of the fault.The shallow structures of the seismogenic fault within the 200 km range are basically the same，and the force exerted by the Bayan Har block on the seismogenic fault is also essentially the same.

Abstract:On March 11，2011，a 9.0 magnitude earthquake occurred on the east coast of Honshu， Japan （N 38.1°，E 142.6°） and triggered a strong tsunami and serious secondary disasters including damage to a nuclear power plant. This earthquake，referred to as Japan MW9.0，was due to movement of the Pacific and adjacent plates，and also caused permanent coseismic displacement in northeast China. With the establishment of the Crustal Movement Observation Network of China （CMONOC） and China Tectonic Environment Monitoring Network（CMTEMN），we can obtain the coseismic displacement through processing and analysis of GNSS post-earthquake data.These data are useful for basic research studying seismic dynamics and characteristics，and for predicting future earthquake trends.Tianjin GNSS network has 23 GNSS stations，which belong to Tianjin Institute of Surveying and Mapping and Earthquake Administration of Tianjin Municipality.This paper examines the effect of the Japan MW9.0 earthquake on the Tianjin area.First，GNSS observation data were collected for the Tianjin area，combined with CMONOC stations and IGS stations around China，and then the crustal activity of Tianjin area after the Japan MW9.0 earthquake was calculated.The data were processed by the GAMIT software and then time series and velocity fields were obtained using QOCA software. The result was analyzed through time series，coseismic displacement，change of length of baseline and the velocity field.The results showed: that many GNSS network stations were permanently displaced a few millimeters in the east direction after the earthquake.Results indicated that the impact of the Japan MW9.0 earthquake was mainly horizontal in the Tianjin area，with no significant change in the north or vertical direction.Coseismic displacement was calculated with 3-day of time-series data from before and after the earthquake.The horizontal direction of coseismic displacement of the stations was the same，namely pointing to the direction of the epicenter；the direction of coseismic displacement in the east was about 8.5~10.1 mm.The length of baseline was also calculated with the time series，and some baselines that crossed the fault were analyzed.From the long-time trend, the entire baseline has an obvious yearly cycle.From the length of the baseline，baseline GGSL-JIXN that crosses the Cangdong fault shows some tension，while baseline WQCG-JIXN that crosses the Baodi fault shows that the baseline length increased slightly after the earthquake due to tensional stress. Results showed that the earthquake created a tensional effect on Tianjin area to some extent. The velocity field changed about 0.1~2 mm/yr in the east direction，while the velocity field in the North-South direction changed only a small amount that was within the error range.

Abstract:Chengdu Basin is located in the front of Longmenshan Mountain，limited between the Longmenshan Mountain and Xiongpo anticline. The two major tectonic systems in the southern margin of Chengdu Basin are the Qiongxi thrust fault system and Xiongpo anticline.The Datang and the Pujiang-Xinjin are the respective major faults with Qiongxi thrust fault system and Xiongpo anticline.The landscape development of the drainages，such as Linxi River and Qingyi River，may have a feedback effect on the Late Quaternary deformation of the tectonic systems.The response relationship between tectonic deformation characteristic and landscape in the southern margin of Chengdu Basin was studied in this paper by interpreting satellite images，conducting field geological investigations，and Digital Terrain Analysis.The late quaternary tectonic deformation characteristic of Qiongxi thrust fault and Xiongpo anticline were emphatically studied in this paper.Our analysis indicates that the middle Pleistocene was an important period of tectonic deformation in the southern margin of Chengdu Basin.Through field investigation，we found that Datang fault is the west reverse fault of the Qiongxi thrust fault system and recent activity along the Datang resulted in the tectonic deformation of Ming-Qiong platform.Pujiang Xinjin fault also dislocated the Yaan gravel layer，which was formed in middle Pleistocene. So the main development and evolution of the Qiongxi thrust fault system and Xiongpo anticline were also in this stage.Because of their tectonic deformation，the ancient Qingyi River had diverted several times left a huge pluvial fan，Ming Qiong platform.Through digital geomorphologic analysis，we derived the drainage sub-basins and their hypsometric interval （HI values） in the Xiongpo area.The swath profile，crossing the southern margin of Chengdu Basin，shows that there are several fold mountains，paralleling the Longmenshan thrust belt.It is the largest terrain gradient zone in study area，and the fold structures also reflect the NW-SE oriented extension of the south segment of Longmenshan thrust belt.We extract the drainage basins from ASTER GDEM data in Xiongpo area and calculated their hypsometric interval （HI values）.The characteristics of the HI values showed that there is a decreasing trend in a SW to NE orientation.The result reflects that the power of the tectonic deformation from the south is stronger to Xiongpo anticline and the deformation process of Xiongpo anticline extended from SW to NE.Our analysis illustrates that the drainage landscape has had an obvious feedback effect on the Late Quaternary tectonic deformation in the southern margin of Chengdu Basin.

Abstract:The Tianshan Mountains, also known as the Snow Mountains, lie across Eurasia to border the Xinjiang Uygur Autonomous Region and Gansu province in eastern China to the western region of The Republic of Kazakhstan and Kyrgyzstan. In the west, the Tianshan Mountains split from the Ili River valley and reveal green valleys and splendid peaks. These mountains are situated between the Tarim plate and the Junggar plate and reach an altitude of 2 500 km and span 300~500 km. The mid-eastern segments of the Tianshan Mountains were selected as the study area (79°-98°E, 39°-46°N), and we utilized 35 051 natural events from 2001 to 2010 to study the crustal velocity structure. The data contains 418 915 P- and S-wave phases, which were recorded by the Xinjiang regional seismic network. We divided the research area with a mesh grid on the basis of the previous results and the character of the seismic ray distribution. Next, the finite difference tomography method and a programmer were used to invert the P- and S-wave velocity disturbance and the P- and S-wave velocity structure. Analysis of the relationship between tomography and corresponding explanations was conducted on the basis of the relationship between velocity structure and great earthquakes in history. An additional velocity model was used with several iterations of calculation to verify our results. The two models showed very close results at the same tectonic position with the same parameters. Therefore, the data and methods are credible in this paper. During the process of the iteration, the results of relocate events and ray tracing error decreased gradually with the iteration time increase. The range of error was relatively narrow after three iterating three times; thus, the third iteration calculation result was used for resolution in this paper. The resolution of image was better at a depth of 60 km, and the result was verified after testing by checkerboard in the study area.  The tomographic results suggest that the deep structures and geodynamics have significant impacts on deformations and earthquake activities in the crust in addition to the mountain building, collision, and dynamics of the entire Tianshan Mountain belt. The fluctuation of the crust velocity structure was dramatic. The low velocity area could be related to the sedimentary layer thickness and the buried depth of the basement. There are obvious high and low velocity gradient zones in the middle and the lower regions of the crust. The distributions of the high and low velocity at 60 km indicate that the dynamic contact mode of the basin and mountains conjunction is limited in the front regions of north and south Tianshan. In addition, the Moho surface depth decreased gradually from the west to the east. At the Junggar basin and Tarim basin conjunction, the Moho surface depth in the N-S direction showed obvious fluctuation. The low-velocity blocks under the basin dipped and squeezed in an opposite direction, and the depth of the Moho layer varied from 48 km to 60 km in the study area. At high and low velocity in a transition band or near the fault that includes medium variation, the region is much more likely to be the seismogenic zone and seismic zone symbol of the strong earthquake. The preliminary results show that the Tianshan Mountain uplift in crust may be related to squeezing in the N-S direction between Junggar basin and Tarim basin. 

Abstract:The traditional intensity attenuation relationship was analyzed using the least squares method fitting.When every observation value is assigned the same weight，outliers are unreasonably treated. Minimizing the sum of squared residuals is the objective in the error checking of the least squares regression model，and the variance is not a robust statistical unit. Therefore，this method is unstable for intensity attenuation. A stable regression for the M estimation method is proposed in this paper.The method was applied to study 117 earthquake macroscopic isoseismic lines，as well as a joint attenuation model.All selected earthquakes from 1716 to 2011 were greater than MS5.0. The results are as follows：Near the epicenter, the intensity attenuation curves in the long axis were close to those in the short axis.With an increase in epicentral distance，the decay of intensity increased along the long and short axis，and along the long shaft it was faster than that along the short shaft. In the far field，the curves of the long axis coincided with those of the short axis.Compared with historical seismic survey data，the simulated intensity of the long and short axial was consistent with the field data in the epicentral region and the far field.Under the same magnitude，the intensity of Tianshan was a slightly higher than that of Arkin and the West Kunlun Mountains in meizoseismal area，which may relate to regional site conditions.In the near field and with the same epicenter distance region, the intensity of Tianshan area was slightly higher than that of Arkin and the West Kunlun Mountains region. In the far field，in the same epicenter distance，the intensity attenuation speed in the Tianshan area was greater than that in the Altun Mountains and West Kunlun Mountains area，which was more obvious when the magnitude was greater than 7.In the far field and under the same magnitude，the attenuation curves of both shafts were similar and tended to be similar in shape to those of the Altun and West Kunlun Mountains.In the same epicenter location near the epicenter，the intensity of West Kunlun Mountains was slightly higher than that of Elgin area.In contrast，the intensity of Altun area was slightly higher than that of KunLun area in the far field position of larger magnitude.By contrast，the actual average rupture scale determined by three regression models indicated that the robust regression model was better than least squares regression and multivariate regression，and it could accurately reflect geological background and attenuation law in the Tianshan area.Therefore，it was the most fit for simulation of the actual value.In short，the robust regression model significantly improved the simulation of seismic intensity attenuation relationship for large magnitudes and has a strong practical significance for earthquake prediction in the region.Furthermore，this method provides reasonable intensity attenuation for regional seismic hazard analysis and seismic zoning.

Abstract:This study surveyed and analyzed the significant mutations of the original observations including observing systems of movement，the natural environment，and buildings affected facilities by examining resistivity observations at Changli station from January 1999 to May 2013. On the basis of this analysis，Changli station has used the curve tracking application and normalized variation rate method （NVRM）approach to analyze earthquakes occurring in the Chinese mainland and the surrounding region since 2000，which include the November 14，2001，West Kunlun Mountain Pass MS8.1 earthquake；the December 26，2004，Sumatra MS8.9 earthquake；the May 12，2008，Wenchuan MS8.0 earthquake；the March 11，2011，level 4 far MS9.0 earthquake in Japan；and the resistivity change of 400 km near Changli station before the earthquakes occurred. The results show a relationship among two trends and three record-breaking abnormalities and far earthquakes in addition to a relationship between these earthquakes and changes in the mechanical state of North crust in a wide range of backgrounds. According to the analysis of nine moderate earthquakes in Bohai area，five occurred within six months of abnormalities，including the abnormal frequency of EW Road between 2008 and 2009 and between 2012 and 2013 and that of NS Road in 2009.Based on the differences in intensity，seismic studies at various distances consider that the analysis of abnormal signals should be combined with the record-breaking abnormal changes，trend changes and transitions，and NVRM processing and analysis methods to analyze observations of Earth resistivity.These differences may be related to the strong earthquakes if there is a distortion or trend in abnormalities lasting 6 to 24 months. However，the level 4 and 5 earthquakes do not generally cause distortions or trend changes.

Abstract:In this study，the isoseismal curve major axis directions of historical earthquakes were counted in the Chongqing area，and the dominant direction was identified.The seismic activity in this area can be roughly divided into two NE strips the route that include one along the Huayingshan fault zone and the other along the Qiyaoshan-Jinfushan fault zone.The Chongqing area is a moderate earthquake region.The historical earthquake space distribution indicates that earthquake occurred in the belt boundary fault of two or three structural units in and NE of the axis of the anticline.The NE fracture structure is dominant in Chongqing area，and the seismogenic structure of most Chongqing earthquakes is a NE-trending fault zone.Rongchang is an earthquake-prone zone in the Chongqing area，which includes seismogenic tectonic earthquakes in the Huayingshan fault zone.On the basis of focal mechanism analysis of Chongqing and adjacent areas，the potential of the seismogenic structure was examined，to provide a basis for evaluating the earthquake isoseismal curve major axis direction. Through the collection of focal mechanism solutions of moderate-strong earthquakes in this area，determination of a composite mechanism solution of small earthquakes，calculation of the focal mechanism of small and moderate earthquakes in Rongchang area，and analysis of the focal mechanism solution features，it is concluded that the tensile principal stress axes and the principal compressive stress axis are nearly horizontal in the area of the modern tectonic stress field，the principal compressive stress is.NW-SE，and the tensile principal stress is NNE-SSW.The predominant distribution of the historical earthquake isoseismal curve major axis direction is NE trending.Through the analysis of the seismic activity and active faults，it was determined that the direction of major axis orientation and active fault lines nearby show better consistency.This result indicates that despite the uncertainty in historical isoseismals for detailed records，the statistical results of long-range distribution for Chongqing，which is a moderate earthquake area，can be used to determine the local seismogenic structure and for seismic rupture location research.A section of the strike of the focal mechanism solution was consistent with the macroseismic intensity survey data obtained by the isoseismal map of long axis direction.After the earthquake，the location of the earthquake epicenter can be evaluated，and the direction of the long axis of the isoseismal can be obtained through the magnitude to develop an isoseismal model for rapid determination of the scope of the disaster.The isoseismal curve major axis direction of historical earthquakes，active faults, and the nodal plane of the focal mechanism solution in the Chongqing area are essentially consistent and can be confirmed by cross correlation.

Abstract:Seismic hazard and risk are two important concepts in engineering design and other policy considerations.Although seismic hazard and risk have often been used interchangeably，they are fundamentally different.Furthermore，seismic risk is more important in engineering design and other policy considerations.Seismic hazard describes the natural phenomenon or property of an earthquake，whereas seismic risk describes the probability of loss or damage that could be caused by a seismic hazard.Seismic hazard assessment is an effort by earth scientists to quantify seismic hazard and its associated uncertainty in time and space from instrumental，historical，and geological observations.Seismic risk quantification is complicated and somewhat subjective because it depends on the desired measurement of consequence（i.e.，outcome of physical interaction between the seismic hazard and exposure）and how the hazard and exposure interact in time and space.Seismic risk assessment can be expressed in many different ways for different users. A model for estimating seismic risk must make assumptions to describe how the hazard and exposure interact in time.In this paper，we first discuss the basic concepts of seismic hazard and risk，and then estimated them from 500-year intensity observations for North China.The key element of this method is to establish the frequency intensity curve that describes the relationship between intensity and annual frequency （or return period）at a site.The main content and steps are described as follows.First，historical intensity observations were collected，the earthquake catalog was checked for completeness，and aftershocks were deleted.Second，the intensity database was geo-referenced in geographic information system （GIS）.Third，based on the characteristic of seismicity，the coverage，geological characteristic and population density，the region was divided into cells in which the intensity observations were digitized in GIS.Fourth，analyses were performed on the digitized intensity records to estimate seismic hazard such as the frequency （or return period）-intensity relationship for each cell.Under the assumption that the occurrences of earthquakes follow Poisson distribution，we also estimate seismic risk in terms of the exceedance probability of intensity I ≥ Ⅶ，Ⅷ，Ⅸ in 50 years，and the corresponding intensity with 10 percent probability of exceedance in 50 years.The results show that North China has high seismic hazard and seismic risk.The results also show that the current design peak ground acceleration （PGA） for many cities in North China，particularly Beijing，Tianjin，and Tangshan，might not be adequate.

Abstract:The provinces of Gansu，Ningxia and Shaanxi are within the region where the Chinese nation originated.Earthquakes frequently occur in these provinces，but most of the region is vast，sparsely populated and far away from the state or county government centers of China.Local earthquake events in the region were not likely to be recorded completely in historical materials，especially if the epicenter was far from cities where it could be felt and reported.Therefore，historical data are likely to be limited and a large number of earthquakes may have been omitted from the records.Historic earthquakes，having their epicenter in the remote regions，may have been felt in cities but because of the distance between epicenter and detection it is difficult to objectively and quantitatively evaluate this historic earthquake activity.Further research on this part of historical data，aimed at more scientifically determining the basic parameters of the omitted moderate-strong historical earthquakes can contribute to a greater understanding of earthquake activity in this area. Improved objective analysis will help to define the social and economic benefits of safety evaluation for major engineering projects or disaster defense.In the study of historical earthquake data and field investigation in Gansu，Ningxia and Shaanxi provinces，we collected data related to ten moderate-strong historical earthquakes.We derived the basic parameters of each earthquake by comprehensive analysis，comparison，and statistical computing for the felt earthquakes.Seismic-tectonic activity in this region was then analyzed using the basic parameters.The strength of earthquakes was calculated using the following formulas：The relation between radius of equivalent circle of IV degree in western China and magnitude given by the Department of Seismic Hazard Prevention of State Seismological Bureau in 1995， is M=1.68lgR+2.24 （1） Where R is the radius of equivalent circle in kilometers and M is magnitude. In addition，another empirical formula given by Jiang Mei et al. （1997），is M=3.04lgRi-0.82 （2） Where Ri is the long radius of feeling area in Gansu，Ningxia and Qinghai provinces in kilometers and M is magnitude.In this study, the estimated magnitude is the average value of applying these two empirical formulas，which allows us to properly consider the local human environment and geographical conditions. The relation between magnitude M and intensity Ⅰ0 in Western China is M=0.605Ⅰ0+1.376 （3） Using this statistical formula，we calculated the intensities of each historical earthquake.The parameters of moderate-strong earthquakes in the Gansu，Ningxia and Shaanxi provinces for which no damage records are available could have important implications for understanding historic patterns and frequency of earthquakes in the region.Through detailed textual research that combines archaeology，science of historical materials，and geology we can develop the record of strong earthquakes that were previously omitted from the catalog for remote areas of northwest China.This can provide scientific and reliable data for seismological research and security of major constructions.

Abstract:China has suffered from many destructive earthquakes in its history.Most of these earthquakes occurred in rural areas and caused huge casualties and economic losses.If we can improve the seismic performance of the rural residential project，it will alleviate the danger of earthquake disaster in rural areas，protect people’s life and property，as well as promote the harmonious development of social and economic resources.However，due to the unpredictability of earthquakes and the limitations of human resources，it is difficult to determine reasonable investments for rural housing structures.This study will calculate the rural construction cost in different seismic fortification criterion and provide a scientific basis for earthquake disaster mitigation.This paper chooses a brick-concrete structure as representative of the rural residential project and the research objective of China’s rural areas.The cost of constructing the brick-concrete structure is calculated under different seismic fortification criteria.The results are that unilateral cost is increased by about 17% in seismic intensity of 6 degrees relative to the undefended cases，and by about 11% for seismic intensity of 6 to 7 degrees, or by about 17% from seismic intensity of 7 to 8 degrees.Through analysis and comparison，we found that differences in rural construction costs of a brick-concrete structure were mostly related to the cost of raw materials.Materials for a brick-concrete structure rural residence increased by about 65%，with the cost of rebar and concrete increasing the most.Our work suggests that it is difficult for the current farmers to independently raise funds for the rural residential project of brick-concrete structures.Our government must provide adequate financial support to assist the rural residents to increase fortification standards for the structures.

Abstract:Yishu fault zone is the most famous fault zone in eastern China. According to the historical earthquake catalog，the MS8.5 Tancheng earthquake occurred in 1668 along one of the zone's faults known as Changyi-Dadian Fault.Because this fault zone is important in the research of geologic history in addition to that of potential earthquake risk，it is well known by geologists and seismologists. Numerous research papers have focused on the tectonic stress field evolution and characteristics of modern tectonic stress fields in the region near Yishu Fault.Regarding the evolution of the tectonic stress field in the region near Yishu Fault, such research has always included information on geodynamics，tectonic deformation，and structural geometry.However，such research is used to determine the characteristics of tectonic stress fields in multiple periods and is generally based on simulation tests and numerical simulation.All of this research is aimed to reveal the tectonic structural framework as well as tectonic evolution to provide an understanding of the inherited and newly created features of tectonics and，in particular，to provide a basis for study of modern tectonic stress fields. In the region near Yishu Fault，modern tectonic stress field studies have generally focused on crustal movement，focal mechanism solutions，borehole strain measurements，and numerical simulation.Because such research also focuses on the characteristics of spatial distribution and the changes of modern tectonic stress fields，it serves as references for analysis of seismic hazard in this region.In this paper，by analyzing numerous studies，we systematically summarize the characteristics of tectonic stress field evolution for the region near Yishu fault zone.Although there are many different theories on the generation of the Tan-Lu fault zone its active features，we conclude that Yishu fault zone originated through large scale left translation in the early years and the later experienced complex tectonic evolution. Finally, determine that the direction of principal stress axes of the ancient tectonic stress field changed significantly along with the active behavior of this fault zone to reach 100 MPa. With developments in technology，current studies of tectonic stress fields are more encouraging，and many new research methods and novel concepts have been explored. In particu