Duration Of Shaking Research Articles

EARTHQUAKE – RESISTANT SLOPE OF BULK STRUCTURES

The article results of various studies, currently the authors are engaged in research on the method of slope positioning, this method differs from others, since this method does not require expensive equipment and technologies for production, it is an economically very profitable method. The development of the slope position method is associated with the stability of the slope, where bulk structures are widely used in construction of various significance. This method has always been built under justification, and with various calculated steepness, has real resistances to various seismic impacts. The slope position method always has its own experience in dealing with antiseismic measures that are built with inexpensive technologies and equipment. Many experts thought that in this method it would be considered a very voluminous work, to the expected concussions, but this method was very relevant at this time and stable. Which were erected by this method (dams, dams, embankments, bridges, supports, etc.) were distinguished by seis mic resistance, since the soils inside had different purposes and they should be resistant to various shocks. The external factor is: the load on the slope surface and the dynamic impact (amplitude, frequency, period, duration of shaking, etc.). The stability of the slope steepness is also affected by: the height of the slope, the method of its construction, as well as the liquefaction of the soil that occurs under the influence of strong shocks. Taking into account all these factors allowed the authors to propose a computational method for assessing the seismic resistance of the slope slope structures. Comparison of the calculation data with the results of experimental studies showed good convergence.

The Effects of Shaking Duration on the Abundance and the Community of Aerobic Denitrifying Bacteria in Shrimp Pond Water and Sediment Samples

With the rapid development of intensive aquaculture, the considerable release of nitrogenous organic compounds has become a serious threat to aquatic organisms. Currently, isolating autochthonous aerobic denitrifying bacteria (ADB) from aquaculture environments is essential for the biological elimination of nitrogenous pollutants. In this study, the enrichment of ADB from shrimp pond water and sediment samples was conducted under different shaking durations. The absolute abundance of total bacteria, nosZ-type, and the napA-type ADB was measured using qPCR. High-throughput sequencing of 16S rRNA, nosZ, and napA genes was performed to reveal the community structure of bacteria and ADB, respectively. Our data revealed that absolute abundance and the community structure of the total bacteria, nosZ-type and napA-type ADB, were significantly altered under different shaking durations. Specifically, the order Pseudomonadales, possessing both nosZ and napA genes, was significantly enriched in water and sediment samples under both 12/12 and 24/0 shaking/static cycles. However, in water samples, compared to the 24/0 shaking/static cycles, the 12/12 shaking/static cycles could lead to a higher enrichment rate of aerobic denitrification bacteria indicated by the higher absolute abundance of bacteria and the higher accounting percentage of orders Oceanospirillales and Vibrionales. Moreover, although the order Pseudomonadales notably increased under the 12/12 of shake/static cycle compared to the 24/0 shaking/static cycle, considering the relative higher abundance of ADB in 24/0 shaking/static cycle, the enrichment of ADB in sediment may be efficient with the 24/0 shaking/static cycle.

Roles of pre- and post-liquefaction stages in dynamic system response of liquefiable sand retained by a sheet-pile wall

This study examines the dynamic system response of a liquefiable deposit retained by a sheet-pile wall, with emphasis on the roles of pre- and post-liquefaction stages of soil response. A recently developed constitutive model, SANISAND-MSf, is utilized to simulate the pre- and post-liquefaction cyclic response of sands. The model is a stress-ratio controlled, critical state compatible, bounding surface plasticity model, which incorporates the concepts of memory surface and semifluidized state. The model’s performance is validated using a combination of cyclic simple shear tests and dynamic centrifuge tests from the LEAP-2020 project. A sensitivity analysis is then conducted by varying the base input motion intensity and duration. The results reveal that the amplitude of equivalent uniform base acceleration in pre-liquefaction correlates well with the timing of liquefaction triggering, and the cumulative absolute velocity of the base acceleration during the post-liquefaction stage correlates well with the post-liquefaction displacements. The study highlights the importance of accurately simulating response in the pre-liquefaction stage for the extent and timing of occurrence of liquefaction, which regulates the remaining intensity and duration of shaking, and in turn, affects the post-liquefaction permanent deformations at the system level.

A review of pre-disaster public awareness activities on public readiness: The 2010 Mentawai tsunami

A qualitative study on impact of pre-disaster public awareness activities on public readiness was conducted in the North and South Pagai Islands after the 25 October 2010 Mentawai earthquake. Parameters of readiness are public response to tsunami and the number of casualties. The results show that public awareness activities that commenced from 2004 have effectively increased people's awareness of tsunamis as indicated by their knowledge of tsunami signals. Yet apart from failure of the official warning system to alert the public in remote areas, the response of people to the natural tsunami signals has been made on the basis of misperceptions of strong earthquake signals and tsunami lead-time. Tsunami lead-time of the Pagai Islands had been perceived as long as that of Sumatra or Java Islands and strong earthquakes have been perceived as merely strong ground shaking. These misperceptions came from invalid materials of public education and invalid translation of scientific information, and were confirmed by people's experiences in the 12 September 2007 Bengkulu earthquake. Hence, despite mitigation by relocating houses to the high ground that has saved many lives in Malakopa and Asahan, there is no evidence on the positive relation of pre-disaster awareness intervention with the reduction in loss of lives in the study sites. In order to not give invalid information on tsunami awareness in the future, instead of using a generic formula of regional tsunamis, public education on tsunami should use a specific formula based on local characteristics. Moreover, sensing earthquakes that may trigger tsunamis through the duration of ground shaking may be more effective than that of the strength of ground shaking. Because sensing time duration is difficult, particularly for communities that are not used to using modern timers, it is necessary to develop simple means of sensing time duration.

Influence of uncertainty of structural parameters on the stochastic dynamic response of asphaltic lining dam-foundation systems to non-stationary random seismic excitation

The present work aims toward the effect of uncertain structural parameters on the stochastic dynamic response of an asphaltic lining dam-foundation system subjected to stationary as well as non-stationary random excitation. Uncertain structural parameters of interest are shear modulus and mass density, modeled using the lognormal distribution. The stochastic seismic response of the dam-foundation system to the random loads with uncertain structural parameters is carried out with the Monte Carlo simulation method. The spatial variability of ground motion is considered with incoherence and wave passage effects as stationary as well as non-stationary random excitation. A time-dependent frequency response function is used throughout the study for non-stationary responses. Obtained results indicate that the variability of shear modulus and mass density can be neglected in stochastic dynamic analysis of an asphaltic lining dam-foundation system. Also, it is seen from the results that stationarity is a reasonable assumption for asphaltic lining dams to typical durations of strong shaking.

Geotechnical reconnaissance findings of the October 30 2020, Mw7.0 Samos Island (Aegean Sea) earthquake

On October 30, 2020 14:51 (UTC), a moment magnitude (Mw) of 7.0 (USGS, EMSC) earthquake occurred in the Aegean Sea north of the island of Samos, Greece. Turkish and Hellenic geotechnical reconnaissance teams were deployed immediately after the event and their findings are documented herein. The predominantly observed failure mechanism was that of earthquake-induced liquefaction and its associated impacts. Such failures are presented and discussed together with a preliminary assessment of the performance of building foundations, slopes and deep excavations, retaining structures and quay walls. On the Anatolian side (Turkey), and with the exception of the Izmir-Bayrakli region where significant site effects were observed, no major geotechnical effects were observed in the form of foundation failures, surface manifestation of liquefaction and lateral soil spreading, rock falls/landslides, failures of deep excavations, retaining structures, quay walls, and subway tunnels. In Samos (Greece), evidence of liquefaction, lateral spreading and damage to quay walls in ports were observed on the northern side of the island. Despite the proximity to the fault (about 10 km), the amplitude and the duration of shaking, the associated liquefaction phenomena were not pervasive. It is further unclear whether the damage to quay walls was due to liquefaction of the underlying soil, or merely due to the inertia of those structures, in conjunction with the presence of soft (yet not necessarily liquefied) foundation soil. A number of rockfalls/landslides were observed but the relevant phenomena were not particularly severe. Similar to the Anatolian side, no failures of engineered retaining structures and major infrastructure such as dams, bridges, viaducts, tunnels were observed in the island of Samos which can be mostly attributed to the lack of such infrastructure.

Optimasi Sterilisasi Eksplan Daun Tanaman Lidah Mertua (Sansevieria sp.) pada Kultur In Vitro

The existence of Sansevieria sp. as an ornamental plant that has many benefits preserved. However, conventional propagation requires a lot of materials and time long. Leaf cuttings are only able to produce 1-2 plants in 2 months, and stop when they are aged 5 months. While the separation of tillers (Tillering) only produces 2-3 plants from 1 clump for 5 months. Tissue culture can be the solution, but sterilization must be done to minimize contamination without killing explants. The research aims to find out optimal concentration of HgCl2 and duration of shaking on the sterilization of Sansevieria leaf explants sp.. The research design used a completely randomized design with 2 factors. first factor namely the concentration of HgCl2 with 3 levels (4%, 7%, and 10%,) and the second factor is duration shuffled with 4 levels (3, 5, 7, and 9 minutes). Each treatment includes a negative control performed at the time of explant sterilization in Laminar Air Flow. Data analyzed by test ANOVA or Kruskal-Wallis. Followed by the 5% BNJ test if it is significantly different. Results show that the concentration of HgCl2 has a significant effect on the parameters of the initial time of contamination, the mass sterility of explants, and percentage of browning explants, but had no significant effect on percentage of contaminated explants. Concentration that is too high can slow down the appearance of contamination, prolonging the sterile period, but causing browning of explants. Known that the duration of explant shaking in HgCl2 had no significant effect on all parameter. The use of 10% HgCl2 with a shaking duration of 7 minutes (H3P3) is known to be the most effective optimal for sterilization of explants Sansevieria sp. because it is able to reduce external contamination, prolongs the sterile period up to 12.33 HST, and does not cause too many explants browning that is 33.33%.

Investigation on Seismic Response of Long‐Span Special Steel Truss Cable‐Stayed Bridge

Due to the small self‐weight of the steel truss cable‐stayed bridge with a single tower and a single cable plane, the torsional stiffness and wind stability of the structure are reduced. The arrangement of the deck type makes the mechanical properties of the cable‐stayed bridge more complicated while reducing the cost and increasing the aesthetics. The effects of structural parameter variations and traveling wave effects on the seismic response of this steel truss cable‐stayed bridge with a single tower and a single cable plane were investigated by the nonlinear time‐history analysis method and nonuniform seismic analysis method. The results show that the displacement of the floating system under seismic action is larger than the other three systems, but its internal force is significantly smaller than the other three systems. The spectral characteristics and the duration of ground shaking have a greater influence on the maximum bending moment values corresponding to the height of the cable tower and the maximum axial force values of the main girder bars corresponding to the length of the bridge under earthquake action. The effect of steel truss girder stiffness parameter variations on structural internal forces of bridges and the effect of traveling wave effects on structural displacements of bridges in specific apparent wave velocity intervals do not exist universally.

Time–Frequency Filter for Computation of Surface Acceleration for Liquefiable Sites: Equivalent Linear Stockwell Analysis Method

This paper presents a novel method for performing equivalent linear analysis that allows for a variation of the stiffness and equivalent viscous damping properties throughout the duration of shaking. The ability to change the dynamic properties throughout the analysis comes from the conversion of the input ground motion into the time-frequency domain using the Stockwell transform whereby different transfer functions can be applied at different times before converting back to the time domain. The equivalent linear Stockwell analysis (ELSA) method provides a fully decoupled approach to modeling the dynamic site response of liquefiable soil deposits that can account for changes in properties due to strain effects and the build-up of excess pore pressure. The simplicity of the method means that only a limited number of dynamic soil properties are required, the same as those used in an equivalent linear analysis, as well as an estimation of the build-up of excess pore pressure and the relative density of the soil. While there are drawbacks of decoupling the estimation of the build-up of excess pore pressure from the dynamic response, this approach means that the effects of liquefaction on ground shaking can be independently assessed using different models for estimating pore pressure. Furthermore, the influence of liquefaction mitigation interventions, or the presence of a building, can present significant modeling challenges for fully-coupled or loosely coupled approaches, whereas they can easily be assessed using simple decoupled tools. Changing the dynamic properties throughout time using the ELSA method provides a rational way to correct equivalent linear analyses for the known drawback of using the same properties throughout the whole duration. Validation studies are presented of the ELSA method against field downhole recordings from the Wildlife Array and fully-coupled nonlinear effective stress analyses.

Utilization of a Gas-Sensing System to Discriminate Smell and to Monitor Fermentation during the Manufacture of Oolong Tea Leaves.

The operational duration of shaking tea leaves is a critical factor in the manufacture of oolong tea; this duration influences the formation of its flavor and fragrance. The current method to control the duration of fermentation relies on the olfactory sense of tea masters; they monitor the entire process through their olfactory sense, and their experience decides the duration of shaking and setting. Because of this human factor and olfactory fatigue, it is difficult to define an optimum duration of shaking and setting; an inappropriate duration of shaking and setting deteriorates the quality of the tea. In this study, we used metal-oxide-semiconductor gas sensors to establish an electronic nose (E-nose) system and tested its feasibility. This research was divided into two experiments: distinguishing samples at various stages and an on-line experiment. The samples of tea leaves at various stages exhibited large differences in the level of grassy smell. From the experience of practitioners and from previous research, the samples could be categorized into three groups: before the first shaking (BS1), before the shaking group, and after the shaking group. We input the experimental results into a linear discriminant analysis to decrease the dimensions and to classify the samples into various groups. The results show that the smell can also be categorized into three groups. After distinguishing the samples with large differences, we conducted an on-line experiment in a tea factory and tried to monitor the smell variation during the manufacturing process. The results from the E-nose were similar to those of the sense of practitioners, which means that an E-nose has the possibility to replace the sensory function of practitioners in the future.

Rapid moment magnitude estimation for large earthquakes in Iran using time integration of absolute ground accelerations

A total of 324 strong ground-motion records from 26 earthquakes with moment magnitude greater than 6 were used to derive an adequate equation for moment magnitude estimation. A parameter called total effective shaking was used to introduce an empirical equation for determining the near real-time magnitude of the Iranian plateau. This parameter was obtained through time integration of the absolute acceleration values from accelerograms over the strong shaking duration. It can be calculated by a simple mathematical procedure 5 seconds after completion of the waveform by decreasing the amplitudes to less than 20% of the maximum ground acceleration. The total effective shaking has a dimension of velocity and corresponds to moment magnitude and hypocentral distance in an attenuation relationship. The optimum coefficients were calculated through least-square regression analysis. Also, the effect of site conditions was evaluated in the analysis. The average shear-wave velocity to a depth of 30 m beneath each recording station was taken into account as the local site effect for 147 records out of the total number of records. The estimated moment magnitudes are in reasonably good agreement with the Global CMT values. Their differences are mostly less than 0.25 in the magnitude unit.

Ground motion prediction equations for significant duration using the KiK-net database

Significant duration of strong shaking quantifies the length of time during which strong earthquake-induced shaking occurs at a given site. Significant duration has multiple applications in Geotechnical and Structural Engineering. However, while multiple ground motion prediction (GMPE) equations for duration exist for shallow crustal tectonic environments, at the time of this publication, there are few published models for predicting significant duration of subduction earthquakes. To address this need and to identify the difference between significant duration of motions resulting from earthquakes in different tectonic regimes, we develop predictive equations for significant duration applicable to interface and intraslab subduction earthquakes and shallow crustal earthquakes in active tectonic regimes using the KiK-net ground motion database. The GMPEs are applicable to earthquakes with M4 to 9. In addition, the influence of earthquake magnitude on duration due to path effects is captured in the proposed relationships. Based on the relationships proposed in this study, we note that the duration of ground motions from subduction earthquakes is longer than those of shallow crustal earthquakes that have similar magnitudes and distances. The predictions of duration for shallow crustal earthquakes in active tectonic regimes developed in this study are consistent with those from previous studies.

Vibration creep of loess soils

Taking into account the rheological properties (creep) of clay soils when solving problems of soil mechanics is important, because many inaccuracies in forecasts related to soils arise from an under-accounting of these properties, which are characteristic of clay soils. The report deals with the issues of vibration creep of moisten loess soils, related to the precipitation of structures and the permissible load on the soil. The method of experimental research and the results of experiments on the dependence of the coefficient of soil vibration creep on the acceleration of vibrations are presented. The factors influencing the vibration creeping deformations of the forest, including the role of soil adhesion and the duration of shaking, are established. Research results are of great importance in the practice of constructing unique engineering structures in seismic areas.

Shallow Basin Structure and Attenuation Are Key to Predicting Long Shaking Duration in Los Angeles Basin

AbstractGround motions in the Los Angeles Basin during large earthquakes are modulated by earthquake ruptures, path effects into the basin, basin effects, and local site response. We analyzed the direct effect of shallow basin structures on shaking duration at a period of 2–10 s in the Los Angeles region through modeling small magnitude, shallow, and deep earthquake pairs. The source depth modulates the basin response, particularly the shaking duration, and these features are a function of path effect and not site condition. Three‐dimensional simulations using the CVM‐S4.26.M01 velocity model show good fitting to the initial portion of the waveforms at periods of 5 s and longer but fail to predict the long shaking duration during shallow events, especially at periods less than 5 s. Simulations using CVM‐H do not match the timing of the initial arrivals as well as CVM‐S4.26.M01, and the strong late arrivals in the CVM‐H simulation travel with an apparent velocity slower than observed. A higher‐quality factor than traditionally assumed may produce synthetics with longer durations but is unable to accurately match the amplitude and phase. Beamforming analysis using dense array data further reveals the long duration surface waves have the same back azimuth as the direct arrivals and are generated at the basin edges, while the later coda waves are scattered from off‐azimuth directions, potentially due to strong, sharp boundaries offshore. Improving the description of these shallow basin structures and attenuation model will enhance our capability to predict long‐period ground motions in basins.

Analgesic potential of dichloromethane leaf extracts of Eucalyptus globulus (Labill) and Senna didymobotrya (Fresenius) in mice models

Introduction: Pain is managed using conventional drugs like paracetamol, aspirin and diclofenac among others. Synthetic drugs have many side effects. This study aimed at evaluating the analgesic potential of the dichloromethane leaf extracts of Eucalyptus globulus and Senna didymobotrya in mice.Methods: The dichloromethane leaf extracts of E. globulus and S. didymobotrya were subjected to quantitative phytochemical analysis using gas chromatography-mass spectrophotometry (GC-MS). In vivo analgesic evaluation comprised of nine groups of animals (Swiss albino mice): normal, positive, negative control and six experimental groups that received 25, 50, 100, 150, 200 and 250 mg/kg body weight of each plant extract intraperitoneally. Thirty minutes later, they were injected with 0.01 mL of 2.5% formalin. The animals in positive control group were administered diclofenac (15 mg/kg) and formalin, the normal control mice received 3% dimethyl sulfoxide (DMSO) in normal saline, while the negative group received DMSO in normal saline and formalin. All the doses were administered intraperitoneally. The duration of shaking and licking of the injected paw was scored and analyzed.Results: The analysis revealed that E. globulus contained alpha-pinenes, endo-fenchol, α-eudesmol, myrcene, camphene, alpha-phellandrene, limonene, and camphor while S. dymobotrya possessed camphene, alpha-phellandrene, limonene, and camphor. In the late phase, E. globulus at the doses of 25, 50, 100, 150, 200 and 250 mg/kg reduced the paw licking time by 34.03%, 60.79%, 84.33 %, 90.65%, 94.49%, 98.52%, respectively while S. didymobotrya extract reduced the paw licking time by 26.48%, 32.96%, 87.04%, 91.27%, 93.40%, 90.97%, and 96.82%, respectively.Conclusion: The results of this study validate and support the traditional uses of these plants as analgesics.

Comparative response of Kashmir Basin and its surroundings to the earthquake shaking based on various site effects

The Kashmir Basin is located in seismic zone V, seismogenic faults and damaging earthquakes of 1555, 1885 and 2005 support this classification. Tectonic features are preserved in older hard rocks, and soft-sediment deformation structures (seismites) in the Karewa deposits. Older basement rocks are overlain unconformably by ~1300 m Karewa deposits followed by unconsolidated fluvial sediments that greatly influence earthquake amplitude and duration of shaking. Seismic waves show a drastic change in peak ground velocity and acceleration when travelling through Karewa deposits. The surrounding epicentre zones are dominated by large earthquakes with shallow depth (4–24 km). Ruggedness, steep-slopes and basin curvature can cause PGA amplification during an unpredicted earthquake. The ill consideration of infrastructure on the water saturated rugged terrain causes ground collapse, and consequently threat to life during seismic shaking. The proximity and linear trend of tectonic structures, epicentre distribution, shallow depth seismicity, thickness and material properties of near surface sediments are unfavourable for safety of the infrastructure and the population.

Development of CO2 capture capacity by using impregnation method in base condition for K2CO3/Al2O3

Carbon dioxide adsorbent is an important factor in the adsorption process of carbon dioxide. Therefore, this study interested in the adsorption of potassium carbonate solid sorbents on gamma-alumina to adsorb carbon dioxide. The added basic solution was used instead of the de-ionized water by assuming that it would give higher support surface area. The various preparation parameters were explored by impregnation method as follows: the different base types (NaOH, Ca(OH)2, and Na2CO3), the basicity of the solution (8, 10 and 12) and the duration of shaking (12, 18 and 24 h). From the results, all parameters affected on the carbon dioxide capture capacity. The sodium hydroxide gave the highest carbon dioxide capture capacity. An increasing in basicity of the solution resulted in higher carbon dioxide capture capacities, since the reactant was acidic. For the effect of the time spent on shaking the adsorbent, the ability to capture carbon dioxide increased with preparation time. The highest adsorption capacity of 4.34 mmol CO2 / g sorbent was obtained from potassium carbonate adsorbent, prepared by using sodium hydroxide with a pH value of 12 and a duration of 24 h while, in normal preparation condition, potassium carbonate adsorbent had a capacity of 2.27 mmol CO2 / g sorbent.

Development of a foam index test method by investigating the effect of test parameters

The foam index test is often performed to determine the air-entraining agent (AEA) dosage when fly ash is used in air-entrained concrete. However, hand-shaking and arbitrary chosen test parameters in the traditional test method lead to deviation between researches. In this paper, a horizontal shaker which can be easily obtained is used to provide automated agitation in a foam index test. The influence of shaking frequencies is investigated at first as the mode of shake is changed. Then, this research focuses on the influence of the water to cementitious materials ratio on foam index. By introducing a model paste consisting simulated pore solution and dead burnt MgO powder, several key factors are isolated. Analysis and discussion suggest that a prolonged shaking duration is more suitable for foam index tests. And by this prolonged method there exists good correlation between foam index and air-entraining agent dosages in fresh mortars.

Hybrid Broadband Seismograms for Seismic Shaking Scenarios: An Application to the Po Plain Sedimentary Basin (Northern Italy)

The densely populated Po Plain, a very deep sedimentary basin in northern Italy, is prone to heavy shaking during earthquakes. Seismic hazard assessment must account for local variation in wave amplification. Standard ground motion prediction equations may fail to picture the complexity of strong lateral gradients in seismic response, due to sharp structural heterogeneity. For this reason, there is an increasing demand for full waveform predictions for engineering applications. Here, we present an implementation of a hybrid broadband simulation based on the method of Mai et al. (Bull Seismol Soc Am 100(6):3338–3339, 2010), to obtain complete broadband seismograms of 0.1–10 Hz. With this method, low frequency (< 1 Hz) and high frequency (1–10 Hz) seismograms are simulated separately using a deterministic and a stochastic method, respectively. We apply the method to four events recorded within the Po basin, with magnitude ranging from Mw = 4.4 to Mw = 5.6. The low frequency (LF) simulation is performed using SPECFEM3D on a few test subsurface velocity models. The three-dimensional velocity model MAMBo (Molinari et al. in Bull Seismol Soc Am 105(2A):753–764, 2015)—consisting of a detailed structural description of the basin, based on extensive active-source data, embedded within a regional 3D crustal model—provided the best results for broadband simulations that most closely corresponded with the observations. It performed better than an ambient noise tomography model with more accurate S-wave velocities but less well defined layer topographies, emphasizing the importance of first order velocity discontinuities. The high frequency (HF) seismograms are simulated using the multiple scattering approach of Zeng et al. (J Geophys Res Solid Earth 96(B1):607–619, 1991). The scattering coefficients are obtained by performing a non linear inversion for each station to find best fitting synthetic envelopes. HF energy is then combined at \(\sim\) 1 Hz to match the amplitude and phase spectra of the LF signal. We are able to simulate full waveforms throughout the Po Plain, of which shaking duration matches observed data for stations located in the basin. Shaking amplitudes are generally overestimated in the low frequency simulation by the MAMBo velocity model. Updating the MAMBo velocity model with more accurate S-wave velocity information of the ambient noise tomography model should improve the fit in future simulations.

Models of Earthquake Ground Shaking Used in Seismic Design and Safety Checks of Large Dams

For the seismic design and seismic safety checks of large storage dams, dynamic analyses have to be carried in the time domain, as inelastic deformations have to be expected under the safety evaluation earthquake ground motion. As input for such analyses acceleration time histories are needed. The characteristics of these time histories are discussed. They may include features such as spectrum matching of recorded or artificial acceleration time histories, aftershocks, directivity effects, near-fault effects, extended duration of strong ground shaking, number of earthquakes, and stochastic independence of earthquake components as listed in the new guideline on the Selection of Seismic Parameters of Large Dams of the International Commission on Large Dams. These acceleration time histories used for dam design are models of earthquake ground motions but have hardly anything in common with real earthquake acceleration time histories, but using such records, the dam engineer can provide a safe design, which is the main objective of the design of any structure.