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1.
The concept of health monitoring is a key aspect of the field of medicine that has been practiced for a long time. A commonly used diagnostic and health monitoring practice is pulse diagnosis, which can be traced back approximately five thousand years in the recorded history of China. With advances in the development of modem technology, the concept of health monitoring of a variety of engineering structures in several applications has begun to attract widespread attention. Of particular interest in this study is the health monitoring of civil structures. It seems natural, and even beneficial, that these two health-monitoring methods, one as applies to the human body and the other to civil structures, should be analyzed and compared. In this paper, the basic concepts and theories of the two monitoring methods are first discussed. Similarities are then summarized and commented upon. It is hoped that this correlation analysis may help provide structural engineers with some insights into the intrinsic concept of using pulse diagnosis in human health monitoring, which may be of some benefit in the development of modem structural health monitoring methods.  相似文献   

2.
A joint effort between the Connecticut Department of Transportation and the University of Connecticut has been underway for more than 20 years to utilize various structural monitoring approaches to assess different bridges in Connecticut. This has been done to determine the performance of existing bridges, refine techniques needed to evaluate different bridge components, and develop approaches that can be used to provide a continuous status of a bridge＇s structural integrity. This paper briefly introduces the background of these studies, with emphasis on recent research and the development of structural health monitoring concepts. This paper presents the results from three different bridge types： a post-tensioned curved concrete box girder bridge, a curved steel box-girder bridge, and a steel multi-girder bridge. The structural health monitoring approaches to be discussed have been successfully tested using field data collected during multi-year monitoring periods, and are based on vibrations, rotations and strains. The goal has been to develop cost-effective strategies to provide critical information needed to manage the State of Connecticut＇s bridge infrastructure.  相似文献   

3.
With the rapid development of the economy in China, the seismic network has been changing rapidly, in that the capability of instruments, technological systems and network density are approaching those of developed countries and a large quantity of observation data has been accumulated. How to apply these resources to economic construction and public safety has become an important issue worth studying. In order to improve earthquake prediction and earthquake emergency response, it is suggested in this paper that extracting valuable precursor information, improving earthquake rapid reporting ability and extending rapid intensity reporting function are key issues. Integrating network resources, building unified standards and a multifunction seismic monitoring network are preconditions of establishing a public safety service platform and earthquake observation resources will contribute significantly to the fields of engineering, ocean, meteorology, and environmental protection. Thus, the future directions of the development of the seismic network are exploring monitoring resources, enhancing independent innovation, constructing a technological platform and enlarging the service field.  相似文献   

4.
In the paper, the establishment, measurement, data-processing program and monitoring accuracy of the GPS seismic monitoring network in North China, especially in the Capital-Circle area, have been presented briefly. The relation of horizontal crustal deformation to tectonic movement, stress-field variation and seismicity has been analyzed in detail. The results indicate that the accuracy of GPS measurement has reached the order of 10-9 and the annual rate of horizontal crustal deformation in North China is about 4 ~5 mm. Horizontal crustal movement is a direct indication of the regional stress field. Therefore, by monitoring the time-sequence variation of horizontal crustal motion, it would be possible to investigate the change in the stress field, to analyze the tendency of seismicity and to determine the seismogenic zones.  相似文献   

5.
Although the CTBT (Comprehensive Nuclear Test-Ban Treaty) was passed in 1996, it is still necessary to develop new and highly efficient methods (Wu Zhongliang, Chen Yuntai, et al.,1993 ; Xu Shaoxie, et al. 1994; Richard L. Garwin, 1994) to monitor possible events. Many discrimination criteria (Xu Shaoxie, et al., 1994 ; Institute of Geophysics, Chinese Academy of Sciences, 1976; Richard L. Garwin, 1994) have been put forward since the 1950s. The results show that each of the existing criteria has its own limitation, but the seismological method is an important and efficient method in the discrimination between nuclear explosion and earthquake. Especially in recent years, because of the little and little equivalent as well as the increasing hiding steps used in the test, a number of more efficient seismological methods have been worked out. In this paper, a new discrimination method, the Wavelet Packet Component Ratio (WPCR) method, is put forward. This method makes full use of the difference in variation with time between the spectra of nuclear explosions and earthquakes. Its discrimination efficiency is rather high.  相似文献   

6.
During the service life of civil engineering structures such as long-span bridges, local damage at key positions may continually accumulate, and may finally result in their sudden failure. One core issue of global vibration-based health monitoring methods is to seek some damage indices that are sensitive to structural damage. This paper proposes an online structural health monitoring method for long-span suspension bridges using wavelet packet transform (WPT). The WPT- based method is based on the energy variations of structural ambient vibration responses decomposed using wavelet packet analysis. The main feature of this method is that the proposed wavelet packet energy spectrum (WPES) has the ability to detect structural damage from ambient vibration tests of a long-span suspension bridge. As an example application, the WPES-based health monitoring system is used on the Runyang Suspension Bridge under daily environmental conditions. The analysis reveals that changes in environmental temperature have a long-term influence on the WPES, while the effect of traffic loadings on the measured WPES of the bridge presents instantaneous changes because of the nonstationary properties of the loadings. The condition indication indices VD reflect the influences of environmental temperature on the dynamic properties of the Runyang Suspension Bridge. The field tests demonstrate that the proposed WPES-based condition indication index VD is a good candidate index for health monitoring of long-span suspension bridges under ambient excitations.  相似文献   

7.
The fault zone along the northern margin of West Qinling Range is a major active fault zonein the key seismic monitoring area in the southeastern part of Gansu Province.In order tostudy the current activity characteristics of this fault,GPS monitoring network has beenarranged along both sides of the fault and 3 measurements have been made from 1996 to1998.The result indicates that obvious differential movement exists along the north and southsides of the fault and the eastward movement on the south side is 3.8mm/a larger than thaton the north side.In the GPS network,the shortened side is generally in the trend of EW andthe extended side is basically NW to SE.The principal compressional stress trend in this areais about EW and the sinistral motion is obvious in the eastern part of the fault(nearWushan).The measured results also indicate that the displacement rate has decreased by50% and the compressional strain has increased by 100% as compared the data of 1997～1998 with those of 1996～1997,which shows t  相似文献   

8.
Local measurement for structural health monitoring   总被引：1，自引：0，他引：1  
Localized nature of damage in structures requires local measurements for structural health monitoring. The local measurement means to measure the local, usually higher modes of the vibration in a structure. Three fundamental issues about the local measurement for structural health monitoring including (1) the necessity of making local measurement, (2) the difficulty of making local measurement and (3) how to make local measurement are addressed in this paper. The results from both the analysis and the tests show that the local measurement can successfully monitor the structural health status as longas the local mod es are excited. Unfortunately, the results also illustrate that it is difficult to excite local modes in a structure. Therefore, in order to carry structural health monitoring into effect, we must ( 1 ) ensure that the local modes are excited, and (2) deploy enough sensors in a structure so that the local modes can be monitored.  相似文献   

9.
Great earthquakes often occur along or near active fault belts. Thus, monitoring and research on fault deformation are quite important. Methods such as short-leveling, short- baseline and integrated monitoring profile across fault belts have been used to monitor fault activities for many years. GNSS observations are mainly used to obtain the horizontal velocity field in large areas and to study the activities and deformation of major blocks. GNSS technology has been used to monitor and study the deformation of faults from a different aspects, In this paper, some applications and new explorations of GNSS are discussed. They are： （1） Research and monitoring of strike-slip activities of faults with GNSS. （2） Research and monitoring of vertical activities of faults with GNSS. （3） Investigating the laws of deformation of blocks on the sides of fault zone and setting up strain models to deduce the activities and deformation of faults with respective models and compare the deduced results with the actual measurements across fault. It is concluded that a larger discrepancy between the deduced and the observed deformation indicates a stronger interaction between the blocks, which can be important for predicting the location of a strong earthquake and assessing seismic hazard, as well as the seismicity trend.  相似文献   

10.
A scour monitoring system with a micro camera tracking the bed-level images is proposed in this study.Two image recognition algorithms have been developed to support the bed-level image tracking approach.Through the laboratory experiments of pier scour,this study demonstrates that the proposed system is able to accurately monitor the scour-depth evolution in real time.In addition,five commonly-used temporal scour models are employed to simulate scour-depth evolution and their results are compared with monitoring data.In general,the results indicate that the proposed scour monitoring system has the potential for further applications in the field.  相似文献   

11.
Introduction In the last 20 years, with observation technique development in space monitoring to Earth, a large progress has been made in monitoring crustal movement. This makes it possible for us to study crustal movement and the present geodynamic. Continuous GPS observation conducted in Chinese mainland and its neighboring region provides us for studying the present strain field of crustal micro-behavior tectonic. Crustal micro-behavior tectonic means that we can study the dif-ference bet…  相似文献   

12.
Sunarjo 《中国地震研究》2002,16(3):217-220
Indonesia is situated at the juncture of three major tectonic plates:the Eurasian,the Pacific and the Indo-Australian Plates,As a result,many parts of the country are classified as being at a high risk of earthquake and tsunami disasters.In Indonesia,the Bureau of Meteorology and Geophysics(BMG)is the agency responsible for the monitoring of tectonic earthquakes and tsunamis induced by them.For this purpose,BMG operates seismic networks throughout Indonsia.In order to serve better,BMG will have to improve its monitoring system.Many agencies and universities in Indonesia have done research in the field of seismology,including seismotectonics,earthquake hazards,and so on.Joint research has been done with agencies/universities from abroad.Considering the fact that some earthquake prone areas in Indonesia suffer from frequent disasters,a study on earthquake prediction in some areas of interest would contribute to achieving some long-term goals of the Bureau.  相似文献   

13.
A trend increase in apparent resistivity has been observed in the N30°E monitoring direction at Garze Seismic Station since July 2011. This increase trend in geo-electric resistivity has been observed in the N60°W direction since 2012. During the period of the increase, the national highway No.317 was expanded in the monitoring area, so the potential electrodes in the N30°E direction had to be moved 10m towards the current electrodes. We interpreted the electric sounding data of Garz6 Seismic Station with a horizontally layered model. Analysis based on this model showed that the shift of potential electrodes can cause a 4 l-l.m rise to the measurements in the N30°E direction. Therefore, apparent resistivity of the two directions increased in the same time in 2012 after offsetting the effects from electrodes shift. Sensitivity coefficients of the two observation directions were also obtained using the model. Sensitivity coefficients of both directions were negative for the shallow layers, which can well explain the unexpected annual variations of Garze Seismic Station. In order to quantitatively analyze the effects from the expansion of the national highway on the observation, we constructed a finite element model based on the electrical structure. Analysis results also suggested that the expansion of the national highway could only cause a 0. 15 Ω·m decrease in the N60°W monitoring direction and 0. 1 Ω· m increase in the N30°E direction. Additionally, the valley values of annual variation of 2013 were distinctively higher than that of other years since 2008, meaning that there was an abnormal rise in apparent resistivity in the two observation directions at Garz~ Seismic Station before the Lushan earthquake. However, the rise was contrary to the decline variation before the Wenchuan earthquake. Therefore, it is still unsure whether or not the rise variation is related to the Lushan earthquake.  相似文献   

14.
Repeating airgun sources are eco-friendly sources for monitoring the changes in the physical properties of subsurface mediums, but their signals decay quickly and are buried in the noises soon after traveling short distances. Stacking waveforms from different airgun shots recorded by a single seismic station (shot stacking) is the most popular technique to detect weak signals from noisy backgrounds, and has been widely used to process the data of Fixed Airgun Signal Transmission Stations (FASTS) in China. However, shot stacking sacrifices the time resolution in monitoring to recover a qualified airgun signal by stacking many shots at distance stations, and also suffers from persistent local noises. In this paper, we carried out several small-aperture seismic array experiments around the Binchuan FAST Station (BCFASTS) in Yunnan Province,China, and applied the array technique to improve airgun signal detection. The results show that seismic array processing combining with shot stacking can suppress seismic noises more efficiently, and provide better signal-to-noise ratio (SNR) and coherent airgun signals with less airgun shots. This work suggests that the array technique is a feasible and promising tool in FAST to increase the time resolution and reduce noise interference on routine monitoring.  相似文献   

15.
The earthquake real-time monitoring system of the Chinese National Digital Seismic Network has been in operation since "the Ninth Five-year Plan" period, and the stability of the system has been well tested. In recent years, with the continuous improvement of monitoring technology and increase of public demands, the original real-time monitoring system needs to be upgraded and improved in terms of timeliness, stability, accuracy and ease of operation. Therefore, by accessing a total of more than 1,000 seismic stations, reducing the seismic trigger threshold of the monitoring system, eliminating the false trigger stations and optimizing the seismic waveform display interface, the current earthquake monitoring demands can be satisfied on the basis of ensuring the stable operation of the system.  相似文献   

16.
In this study, a new lumped-mass-stick model (LMSM) is developed based on the modal characteristics of a structure such as eigenvalues and eigenvectors. The simplified model, named the "frequency adaptive lumped-massstick model," hasonly a small number of stick elements and nodes to provide the same natural frequencies of the structure and is applied to a nuclear containment building. To investigate the numerical performance of the LMSM, a time history analysis is carried out on both the LMSM and the finite element model (FEM) for a nuclear containment building. A comparison of the results shows that the dynamic responses of the LMSM in terms of displacement and acceleration are almost identical to those of the FEM. In addition, the results in terms of floor response spectra at certain elevations are also in good agreement.  相似文献   

17.
NIR-red spectral space based new method for soil moisture monitoring   总被引：4，自引：0，他引：4  
Drought is a complex natural disaster that occurs frequently. Soil moisture has been the main issue in remote monitoring of drought events as the most direct and important variable describing the drought. Spatio-temporal distribution and variation of soil moisture evidently affect surface evapotranspiration, agricultural water demand, etc. In this paper, a new simple method for soil moisture monitoring is de- veloped using near-infrared versus red (NIR-red) spectral reflectance space. First, NIR-red spectral reflectance space is established using atmospheric and geometric corrected ETM data, which is manifested by a triangle shape, in which different surface covers have similar spatial distribution rules. Next, the model of soil moisture monitoring by remote sensing (SMMRS) is developed on the basis of the distribution characteristics of soil moisture in the NIR-red spectral reflectance space. Then, the SMMRS model is validated by comparison with field measured soil moisture data at different depths. The results showed that satellite estimated soil moisture by SMMRS is highly accordant with field measured data at 5 cm soil depth and average soil moisture at 0―20 cm soil depths, correlation coef- ficients are 0.80 and 0.87, respectively. This paper concludes that, being simple and effective, the SMMRS model has great potential to estimate surface moisture conditions.  相似文献   

18.
Introduction Seismic monitoring is one of the most important approaches for ground-based nuclear explo-sion monitoring (CTBTO, 1998). The trend in this research field is to improve the monitoring ca-pability for low magnitude seismic events in regional scales. Seismic monitoring mainly includes detection, location, identification and characterization of seismic events. The correctness and accuracy of all of them depend on the quality of seismic re-cords and the degrees of uncertainties of ge…  相似文献   

19.
Structural health monitoring of RC structures under seismic loads has recently attracted much attention in the earthquake engineering research community. In this study, a piezoceramic-based device called "smart aggregate" was used for the health monitoring of RC frame structures under earthquake excitations. Three RC moment frames instrumented with smart aggregates were tested using a shaketable with different ground excitation intensities. Distributed piezoceramic- based smart aggregates were embedded in the RC structures and used to monitor their health condition during the tests. The sensitivity and effectiveness of the proposed piezoceramic-based approach were investigated and evaluated by analyzing the measured responses. The displacement ductility demand of the structural members was calculated and compared with the damage index determined from the health monitoring system. The comparison shows that the damage index is compatible with the calculated ductility demand.  相似文献   

20.
The hydrofracturing technique has developed into a reliable and practical method for determining the original three-dimensional crustal stress state of underground caverns,the load-bearing capacity of a high pressure cavern itself,and the high pressure hydraulic permeability of rock masses,and has also been extensively used in disposal of nuclear waste,long and deeply-buried traffic channels and high-pressure cavern engineering for hydraulic power plants.The practice shows that the comprehensive measurement of the physical parameters of the rock mass and taking full use of the wall rock load-bearing capacity to optimize the engineering design hold are very useful in ensuring the engineering safety and improving the design level.  相似文献   

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