Comparison of engineering failures and seismic responses of 500 kV transformer-bushing systems in the 2022 Luding earthquake

Cemented and mechanically clamped types of end fittings(fitting-C and fitting-M)are commonly used in transformer bushings.During the Luding Ms 6.8 earthquake that occurred in China on September 5,2022,all transformer bushings with the two types of end fittings in a 500 kV substation were damaged.Post-earthquake field investigations were conducted,and the failures of the two types of bushings were compared.Two elementary simulation models of the transformer-bushing systems were developed to simulate the engineering failures,and further compute their seismic responses for comparison.The results indicate that the hitch lugs of the connection flange are structurally harmful to seismic resistance.Fitting-M can decrease the bending stiffness of the bushing due to the flexible sealing rubber gasket.Since it provides a more flexible connection that dissipates energy,the peak accelerations and relative displacements at the top of the bushing are significantly lower than those of the bushing with fitting-C.Compared with fitting-C,fitting-M transfers the high-stress areas from the connection flange to the root of the porcelain,so the latter becomes the most vulnerable component.Fitting-M increases the failure risk of the low-strength porcelain,indicating the unsuitability of applying it in high-intensity fortification regions.

Earthquake Emergency Response System of High-speed Railway by Least Square Method

This paper studies the Least Square Method to define high-speed railway(HSR) earthquake risk and solve the problem of its emergency response mechanism. Based on the construction of a monitoring system for HSR earthquake emergency response, the technical operational procedures for HSR seismic emergency response are proposed. The quantity, scale, and location of HSR earthquake emergency response mechanism are defined, and the corresponding emergency response system is built. In particular, the earthquake emergency response system can conduct real-time continuous dynamic monitoring of seismic activity along the railway. When earthquake occurs, the intensity of the ground motion is detected by the system. When the earthquake monitoring value reaches the earthquake alarm threshold, it will send an alarm signal to the dispatch center, and the emergency power supply will be forced to cut off. The earthquake emergency response system will continue to monitor the follow-up ground motion acceleration. The system provides the operation scheduling center with a basis for train operation control to resume operation after stopping. The monitoring result of the system reduces the disaster, and the secondary disaster is caused by the earthquake. This paper improves the HSR response mechanism in detecting earthquake disasters. The result improves the ability of HSR to deal with earthquake disasters, and reduces casualties and economic and property loss caused by earthquake disasters.

Ideal Drift Response Curve for Robust Optimal Damper Design for Elastic-Plastic MDOF Structures under Multi-Level Earthquakes Dedicated to Professor Karl S.Pister for his 95th birthday

A new method of robust damper design is presented for elastic-plastic multi-degree-of-freedom(MDOF)building structures under multi-level ground motions(GMs).This method realizes a design that is effective for various levels of GMs.The robustness of a design is measured by an incremental dynamic analysis(IDA)curve and an ideal drift response curve(IDRC).The IDRC is a plot of the optimized maximum deformation under a constraint on the total damper quantity vs.the design level of the GMs.The total damper quantity corresponds to the total cost of the added dampers.First,a problem of generation of IDRCs is stated.Then,its solution algorithm,which consists of the sensitivity-based algorithm(SBA)and a local search method,is proposed.In the application of the SBA,the passive added dampers are removed sequentially under the specified-level GMs.On the other hand,the proposed local search method can search the optimal solutions for a constant total damper quantity under GMs’increased levels.In this way,combining these two algorithms enables the comprehensive search of the optimal solutions for various conditions of the status of the GMs and the total damper quantity.The influence of selecting the type of added dampers(oil,hysteretic,and so on)and the selection of the input GMs on the IDRCs are investigated.Finally,a robust optimal design problem is formulated,and a simple local search-based algorithm is proposed.A simple index using the IDRC and the IDA curve of the model is used as the objective function.It is demonstrated that the proposed algorithm works well in spite of its simplicity.

Dynamic response of mountain tunnel,bridge,and embankment along the Sichuan-Tibet transportation corridor to active fault based on model tests

The Sichuan-Tibet transportation corridor is prone to numerous active faults and frequent strong earthquakes.While extensive studies have individually explored the effect of active faults and strong earthquakes on different engineering structures,their combined effect remains unclear.This research employed multiple physical model tests to investigate the dynamic response of various engineering structures,including tunnels,bridges,and embankments,under the simultaneous influence of cumulative earthquakes and stick-slip misalignment of an active fault.The prototype selected for this study was the Kanding No.2 tunnel,which crosses the Yunongxi fault zone within the Sichuan-Tibet transportation corridor.The results demonstrated that the tunnel,bridge,and embankment exhibited amplification in response to the input seismic wave,with the amplification effect gradually decreasing as the input peak ground acceleration(PGA)increased.The PGAs of different engineering structures were weakened by the fault rupture zone.Nevertheless,the misalignment of the active fault may decrease the overall stiffness of the engineering structure,leading to more severe damage,with a small contribution from seismic vibration.Additionally,the seismic vibration effect might be enlarged with the height of the engineering structure,and the tunnel is supposed to have a smaller PGA and lower dynamic earth pressure compared to bridges and embankments in strong earthquake zones crossing active faults.The findings contribute valuable insights for evaluating the dynamic response of various engineering structures crossing an active fault and provide an experimental reference for secure engineering design in the challenging conditions of the Sichuan-Tibet transportation corridor.

Simulation and Traffic Safety Assessment of Heavy-Haul Railway Train-Bridge Coupling System under Earthquake Action

Aiming at the problem that it is difficult to obtain the explicit expression of the structural matrix in the traditional train-bridge coupling vibration analysis,a combined simulation system of train-bridge coupling system(TBCS)under earthquake(MAETB)is developed based on the cooperative work of MATLAB and ANSYS.The simulation system is used to analyze the dynamic parameters of the TBCS of a prestressed concrete continuous rigid frame bridge benchmark model of a heavy-haul railway.The influence of different driving speeds,seismic wave intensities,and traveling wave effects on the dynamic response of the TBCS under the actions of the earthquakes is discussed.The results show that the bridge displacement increase in magnitude in the lateral direction is more significant than in the vertical direction under the action of an earthquake.The traveling wave effect can significantly reduce the lateral response of the bridge,but it will significantly increase the train derailment coefficient.When the earthquake intensity exceeds 0.2 g,the partial derailment coefficient of the train has exceeded the limit value of the specification.

Bi-normalized response spectral characteristics of the 1999 Chi-Chi earthquake

To develop uniform and seismic environment-dependent design spectrum,common acceleration response spectral characteristics need to be identified.In this paper,a bi-normalized response spectrum (BNRS) is proposed,which is defined as a spectrum of peak response acceleration normalized with respect to peak acceleration of the excitation plotted vs.the natural period of the system normalized with respect to the spectrum predominant period,Tp.Based on a statistical analysis of records from the 1999 Chi-Chi earthquake,the conventionally normalized response spectrum(NRS) and the BNRS are examined to account for the effects of soil conditions,epicentral distance,hanging wall and damping.It is found that compared to the NRS the BNRS is much less dependent on these factors.Finally,some simple relationships between the BNRS for a specified damping ratio and that for a damping ratio of 5%,and between the spectra predominant period and epicentral distance for different soil types are provided.

Analysis of the Effects of Slope Geometry on the Dynamic Response of a Near-field Mountain from the Wenchuan Earthquake

Fourier spectra and acceleration response spectra of near-field acceleration records of the 2008 Wenchuan Earthquake have been calculated.Relative fundamental frequencies(or predominant periods) were characterized.Then,the natural frequencies of a range of slopes with different geometric characteristics,such as height,slope ratio,and pattern,were analyzed.The seismic responses of the slopes were compared,and the variability of seismic response with the above geometric elements was found.Results show that if slope height increases,and provided that other conditions are unchanged,the natural frequency of the first mode of a doublesurface slope will change as a power law.However,natural frequencies will diminish(based on a parabolic function) as the slope angle becomes large.Both the surface pattern and the number of surfaces on a slope can have a great impact on the seismic response of the slope.Moreover,within a certain range of slope heights or angles,either height or angle will also greatly influence the variability of the seismic response.The results of this research will be helpful to understanding seismic dynamic response features and explaining the ways that slope stability can be affected by earthquakes.

Characteristics of response spectra for long-periods of main-shock recordings of the Chi-Chi earthquake

Current practice uses predictive models to extrapolate long-period response spectra based on far-field recordings in moderate and weak earthquakes. However, the spectra are not long enough and the data are often not reliable, which means that the seismic design code cannot accurately define seismic design requirements for long-period structures. The near-field recordings in the main-shock of the Chi-Chi earthquake have a large signal-to-noise ratio （SNR）, which makes them suitable for studying the long-period acceleration response spectrum up to 20 sec. The acceleration response spectra from 246 stations within 120 km of the causative fault are statistically analyzed in this paper. The influence of distance and site conditions on long-period response spectrum is discussed, and the shapes of the amplification spectra are compared with the standard spectra specified in the seismic design code of China. Finally, suggestions for future revisions to the code are proposed.

Site response in the Qionghai Basin in the Wenchuan earthquake

Amplification effects of soil site response can significantly impact ground motions, and must be considered in the seismic fortification of buildings/structures to prevent or mitigate this potential seismic hazard. Utilizing acceleration time histories from the main shock of the Wenchuan earthquake recorded at four stations （i.e., one on bedrock and three on soil） in the Qionghai Basin, the site responses from three soil sites are studied by using the traditional spectral ratio method. The bedrock site is selected as a reference site. This study found that peak ground accelerations （PGAs） on the soil sites are much larger than on bedrock, with EW, NS and UD components of 3.96-6.58, 6.27-10.98, and 3.17-6.66 times those of the bedrock site, respectively. The amplification effects of the soil sites on ground motions in the frequency range of 0.1 Hz to 10 Hz are significant, depending on the thickness of the soil layer and the frequency content of the site. A significant amplification occurs with high frequency components of ground motion at shallow soil sites, and low and high frequency components of ground motion at intermediate soil sites.

Directional seismic response to the complex topography:A case study of 2013 Lushan Ms 7.0 earthquake

Azimuthal variations in site response can provide a good insight into the site amplification and seismic conditions of geohazard occurrences.In this study,multiple directional site response methods,including D-Arias(Directional-Arias),D-SER(Directional-Shaking energy ratio),D-HVSR(Directional-Horizontal to vertical spectral ratio)and D-SSR(Directional–Standard spectral ratio),are adopted to analyse seismic data of the 2013 Lushan Ms 7.0 earthquake captured by the self-established Lengzhuguan(LZG)station which consists of the complex topography of isolated ridge,large mountain and some typical micro-reliefs.The results show that the isolated ridge could cause stronger site responses than the large mountain,and whose pronounced response direction is roughly perpendicular to its ridgeline.With the growth of elevation,the siteresonant frequency decreases.The different microreliefs on the mountain cause different site responses,which present as protruding slope>linear slope.The site response mainly exists on the surficial layer of the mountain and shows that with the increase of the distance to mountain surface,the site response gets weaker,the site resonant frequency gets higher,and the pronounced response direction is perpendicular to its ridgeline.

INELASTIC COUPLED RESPONSE OF ECCENTRIC BUILDINGS WITH RESPECT TO DIFFERENT EARTHQUAKE INTENSITY

Using five-story shear models, the inelastic torsional coupled response of eccentric buildings to different earthquake intensity was studied. Results show that the torsional couple degree is closely related to the strength distribution of the resisting elements. Generally, the building designed by spectral modal analysis method has a tendency to move translationally as the earthquake intensity increases. The building designed by proportion rigidity method, will rotate heavily to moderate earthquake, but when it is intensively excited into the inelastic phase, the coupling would decrease slightly, but could not be neglected.

Application of GIS to build earthquake emergency response system for urban area

A GIS based decision making system is designed for earthquake emergency response for city governments. The system could be used for seismic hazard assessment, earthquake damage and losses evaluation, emergency response and post earthquake recovering. The principle, design criteria, structure and functions of the system are described in detials. The system is composed of four parts: an information and data base, analytical modules, a decision making subsystem and a user interface. The information and data base consists of 68 coverages, including historically and instrumentally recorded earthquakes, seismo tectonic zones, active faults, potential source areas, isoseismals of scenario earthquake, soil profiles, characteristics of buildings, and all infrastructure systems such as: transportation network (roads and bridges, culverts), oil pipeline network, gas, water, electric power, communication etc., distribution of citizens, rush repair schemes of infrastructures and so on. There are also 28 analytical modules established in the system for generating isoseismals of scenario earthquake, site effects estimation, damage and losses evaluation and decision making for rescue, relief, evacuation and other emergency response actions. As an illustration, the operation of this system for reoccurrence of a historical earthquake is demonstrated.

Co-seismic responses of water wells in Jiangsu province to 2008 Wenchuan and 2011 Japan earthquakes

Co-seismic water-level and temperature changes of the 2008 magnitude - 8.0 Wenchuan and the 2011 magnitude-9.0 Japan earthquakes recorded at 10 observation wells in Jiangsu province are presented and analyzed. The data show that water level responded more regularly with earthquake magnitude and dis- tance than water temperature. The response was different for wells located in different tectonic units, being weaker in central and northern plain, which has a relatively thick surface layer of loess, than southern Jiangsu, which is hilly.

Analysis of the co-seismic responses of the fluid well pattern system in Jiangsu Province to the Wenchuan and Tohoku earthquakes

This thesis discusses the earthquake reflecting ability of the observation well pattern system of Jiangsu Province, China, which has been digitally renovated, and probes into the cause of the major differences in the earthquake reflecting abilities of well holes at different measurement points. This is achieved through the analysis of the co-seismic responses to the Wenchuan (2008; Ms8.0, China) and Tohoku (2011; Ms9.0, Japan) earthquakes. We found that the co-seismic response of water level from regional well holes in Jiangsu Province was stronger than that of water temperature. The water-level co-seismic response follows a consistent law and is closely related to the earthquake magnitude. The co-seismic response of water temperature strongly varied among well points, and was more often manifested as a slow restorative change. The co-seismic responses also varied based on tectonic elements. The response in central and northern Jiangsu was weaker than that of southern Jiangsu, possibly due to the thicker loess cover layer in central Jiangsu which makes it less effective at capturing the micro-changes of stress-strain states relative to the hilly land in the south. The more complicated geological structure in southern Jiangsu makes it contribute to greater changes in the state of underground water after a minor disturbance.

Stochastic Response Analysis of Piled Offshore Platforms to Earthquake Load

In this paper, using the theory of stochastic analysis of the response to earthquake load, a stochastic analysis method of the response of piled platforms to earthquake load has been established. In the method, the strong ground motion is considered as three dimensional stationary white noise process and the pile-soil interaction and water-structure interaction are considered. The stochastic response of a typical platform to earthquake load has been computed with this method and the results compared with those obtained with the response spectrum analysis method. The comparison shows that the stochastic analysis method of the response of piled platforms to earthquake load is suitable for this kind of analysis.

Patient tracking in earthquake emergency response in Iran： A qualitative study

BACKGROUND: After a disaster, all victims have to be rapidly and accurately identified for locating, tracking and regulating them. The purpose of this study was to summarize people's experiences that how the patients were tracked in past earthquake disasters in Iran.METHODS: A qualitative study was carried out in 2015. This was an interview-based qualitative study using content analysis. The interviewed people included physicians, nurses, emergency medical technicians, disaster managers, Red Crescent Society' first responders and managers. Participants were identified using a snow ball sampling method. Interviews were audiotaped, transcribed, coded, and entered into MAXQDA(version 10) for coding and content analysis.RESULTS: Three main themes and seven categories including content(recoding data), function(identification of victims, identification of the deceased, informing the patients' relatives, patients' evacuation and transfer, and statistical reporting), technology(the state of using technology) were identifi ed that showed the patient tracking status in past earthquakes in Iran.CONCLUSION: Participants believed that to identify and register the data related to patients or the dead, no consistent action plan was available. So developing a consistent patient tracking system could overcome this issue and improve patient safety.

Earthquake Response and Isolation Layer Parameter Effect of Seismic Isolation Systems of Transformers With Bushings

国内外震害表明，变压器在地震中的破坏型式多样，易损性极高。隔震技术是一项能够有效降低地震反应的新型抗震技术，而变压器及套管隔震层的设计和参数选择与普通结构有较大的差异。首先，建立了大型电力变压器及套管隔震体系的多质点分析模型，采用Matlab软件编写计算程序，分别输入人工地震波和Taft地震波，对变压器及套管隔震体系的地震响应进行分析；最后，开展了隔震层等效水平网0度、等效阻尼比、双线性恢复力模型的屈服剪力系数及屈服后刚度等参数的地震响应影响分析。分析结果表明：合理设计变压器及套管隔震体系的隔震层参数，可有效降低变压器及套管的地震响应；另外，通过隔震层的参数分析，得到了相关参数的合理取值范围。该研究对今后变压器及套管隔震体系的设计具有参考与指导作用。

The response law of far-field seismic ground motion of the Wenchuan earthquake and its damaging mechanism in the Loess Plateau

A series of housing collapses and other serious damage was caused by the 2008 Wenchuan M_(S)8.0 earthquake in the seismic intensity Ⅵ areas of the Loess Plateau, which is hundreds of kilometers away from the epicenter, and which showed a remarkable seismic intensity anomaly. The seismic disasters are closely related to the seismic response characteristics of the site, therefore, the systematic study of the far-field seismic response law of the Wenchuan earthquake in the Loess Plateau is of great significance to prevent the far-field disaster of great earthquake. In this paper, the seismic acceleration records of several bedrock stations and loess stations from the seismogenic fault of the Wenchuan earthquake to the Loess Plateau were collected, and the attenuation law of ground motion along the propagation path and the characteristics of seismic response on the loess site are studied,and the mechanism of amplification effect of ground motion is analyzed based on the dynamic feature parameters of the loess site obtained through the HVSR method. Taking a typical loess site of thick deposit as the prototype, a series of shaking table tests of dynamic response of loess site models with different thicknesses were carried out.Amplification effect, spectral characteristics of acceleration in model sites were analyzed under the action of a farfield seismic wave of the Wenchuan earthquake. The results show that seismic attenuation on the propagation path along the NE strike of the seismogenic fault to the Loess Plateau is slower than that in other directions, and the predominant period range of ground motion on bedrock site of the Loess Plateau presents broadband characteristics. Because the natural periods of loess sites with thick deposits are within the predominant period range of bedrock input wave, loess sites appear significant amplification effect of ground motion, the horizontal acceleration of ground motion exceeds 0.1 g, the seismic intensity reaches 7°. The thicker the loess deposit is, the more significant the change of spectral characteristics of ground motion on loess sites, and the narrower the predominant period range of ground motion becomes, and the closer it is to the natural period of loess sites.Therefore, for some old houses on thick loess sites, the poor seismic performance and strong seismic response eventually led to their collapses and damages because their natural periods are very close to the predominant period of ground motion of the Wenchuan earthquake on thick loess sites;For these damaged high-rise buildings,the resonance effect might be the main reason for their damages because their natural periods are included in the predominant period range of ground motion of the Wenchuan earthquake on thick loess sites.These research results would provide a basis for seismic disasters prediction and evaluation and seismic design of construction engineering in the Loess Plateau.

The Experimental Simulation of Rocks on Load/Unload Response Ratio for Earthquake Prediction

The load/unload experiments on rock failure under pressure have been carried out in Material Test System (MTS) in the Laboratory for Non-linear Mechanics of Continuous Media (LNM), Institute of Mechanics, Chinese Academy of Sciences, and load/unload response ratio (LURR) values with strain as response (i.e. inverse elastic constant as response rate) have been obtained. The experimental results are in accordance with theoretical results and those in real earthquakes: LURR rises just before rock failure. So LURR can be used as the precursor of rock failure and earthquake prediction.

Numerical Simulation of Coseismic Response and Its Mechanism of Well Water Temperature to Farfield Strong Earthquakes1

Heat flow is inevitably accompanied by temperature change,thus,the water temperature coseismic response during earthquake activity should also obey the laws of thermodynamics.Taking the M S8.0 Wenchuan,Sichuan,China earthquake and the M9.0Tohoku,Japan earthquake as an example,and based on the data of water temperature coseismic responses observed in well ZK26 in Haikou,Hainan Province,China,we investigate the relationship between well water temperature change and heat transfer in the coseismic response process and the relevant thermodynamic mechanism by using the numerical simulation method for thermodynamic equations.Then,through forward modeling,we obtain several simulation curves of water temperature change in response to earthquakes along the well depth at different times.The simulated curves of water temperature change approximately fit the observed curves.Consequently,based on the variation of temperature,we find that the modes of well water temperature coseismic response( ascending,descending or stable) are related to factors such as the location of sensors,distribution and location of heat sources,the span between sensors and heat sources.