The duration of the ground motion has a strong influence on the damages produced by the seismic event. The accelerogram measures the ground motion from beginning to end, which may include very small amplitudes at the beginning (10 seconds) and at the end (20 seconds) of the accelerogram. Seed [2,3] has defined the duration of the earthquake from a magnitude that may produce effects on the structure. Seed call to this condition bracketed duration which normally is indicated as 0.05g. Kramer  presents several methods to define the proper duration of the ground motion. The accelerogram had duration of 120 seconds, but after an assessment of the frequency content it was reduced to 90 seconds (Bracketed accelerogram) by removing very small amplitudes that will not affect the embankment. The duration of this particular earthquake can be reduced even more if Seed’s bracketed criterion would be applied at the beginning and end of the accelerogram. Figure 1 shows the bracketed acceleration time history in a horizontal and vertical direction of a subduction zone earthquake that could shake the dam site. THE EMBANKMENT
In this study, seismic soil liquefaction is evaluated in terms LPI using SPT- based simplified empirical procedure. An earthquake triggered at one hypocenter is of one moment magnitude, but it produces groundmotions of different PGA values at different sites depending on source characteristics, epicentral distances, effects of travel path on the seismic waves, and local site conditions. Many moderate earthquakes generate groundmotions of larger PGA values than those of major earthquakes. Ground motion varies significantly over very short distances due to variation in soil type and the thickness of soil deposit (Boatwright et al., 1991). Variations in PGA of surface level groundmotions due to small dif- ferences in local soil conditions and geological features be- tween nearby sites can be high in the city, and therefore one PGA value can correspond to earthquakes of different magni- tudes. Therefore, this study attempts to perform liquefactionpotential analyses for earthquakes of magnitudes M w = 6.0,
One of the important problems in earthquake geotechnical engineering is liquefaction phenomenon that happens in loose saturated granular soils. This phenomenon can cause great damages to underground structures and buildings and lifelines. Liquefaction resistance of soils can be evaluated by experimental and field tests. In this research, results of liquefactionpotential evaluation based on standard penetration test (SPT) were proposed. Case study area is Southeast of Khoy city at West Azerbaijan province in Iran. In this study 18 boreholes was collected. With considering type of soils and ground-water table level liquefactionpotential evaluated. Then, liquefactionpotential index (LPI) assessed. Obtained results showed that almost more of 50% alluvium sediments deposits is included sand and silty sand. Also, liquefactionpotential hazard with considering ground water table level is high.
Abstract. Liquefaction is one of the critical problems in geotechnical engineering. High ground water levels and al- luvial soils have a high potential risk for damage due to liq- uefaction, especially in seismically active regions. Eskis¸ehir urban area, studied in this article, is situated within the sec- ond degree earthquake region on the seismic hazard zona- tion map of Turkey and is surrounded by Eskis¸ehir, North Anatolian, K¨utahya and Simav Fault Zones. Geotechnical investigations are carried out in two stages: field and labo- ratory. In the first stage, 232 boreholes in different locations were drilled and Standard Penetration Test (SPT) was per- formed. Test pits at 106 different locations were also exca- vated to support geotechnical data obtained from field tests. In the second stage, experimental studies were performed to determine the Atterberg limits and physical properties of soils. Liquefactionpotential was investigated by a simpli- fied method based on SPT. A scenario earthquake of magni- tude M = 6.4, produced by Eskis¸ehir Fault Zone, was used in the calculations. Analyses were carried out for PGA lev- els at 0.19, 0.30 and 0.47 g. The results of the analyses indi- cate that presence of high ground water level and alluvial soil increase the liquefactionpotential with the seismic features of the region. Following the analyses, liquefactionpotential maps were produced for different depth intervals and can be used effectively for development plans and risk management practices in Eskis¸ehir.
Taipei City affected PGA greater than 250 gals from Mw 6.88, 6.33 earthquakes are 2,238,028 and 776,384, respectively. As a result, the fatalities in Taipei City are 4904 and 1726, respectively for Mw 6.88 and 6.33. Moreover, the numbers of fatalities tend to increase rapidly for people above age 45. The fatalities reached a high peak in age groups of 55– 64 from these scenario earthquakes on the Sanchiao fault. Finally, from the past study, the primary cause of death for the victims of the Chi-Chi earthquake was structural failure. Hence, the author concern and worry about the capacity of old buildings to resist strong shaking, especially has hundreds of thousands of households whose residences over 40 years old in the city center where population is highly concentrated. The results of this study will enable both local and central governments to take notice of potential earthquake threat in these areas, as well as to improve decision making with respect to emergency preparedness, response, and recovery activities for earthquakes in Taipei City.
Baghdad city is located in the middle part of Mesopotamian alluvial plain. As Baghdad City is located at Tigris River, and the Euphrates River is about 40 km away, so its sediments are recent not exceeding Quaternary ages. Generally the soil of Baghdad City has been derived from around areas especially Mesopotamian plain and the desert (Buringh, 1960). Most soils of Baghdad City are therefore secondary soils (residual soils) derived from the above regions, transported from place of weathering and accumulated as a result of sedimentation. Besides, Baghdad soil strata are affected by river course changes during previous decades leading to coarse silt deposits and giving different depositional stratigraphy each few meters, thus Baghdad strata are erratic, somewhat are nonhomogeneous with a water table near ground. Baghdad soil in generally is alkaline with poor permeability (NCCL, 1986; Hattab et al., 1986; Karim and Schanz, 2006).
consistent “potential displacement” is detected, to the total number of the neighbouring GPS stations. If this ratio is higher than a pre-defined threshold w, which ranges between 0 and 1, then the “potential displacement” corresponds to real seismic displacement, otherwise the algorithm initialise from the beginning for the next epoch i+1. However, if there is continuous result of „potential displacement‟ from a specific GPS site or a group of GPS sites, but still the ratio is lower than the threshold, this would be the result of real displacement due to local ground displacement or foundation instability or result of artefact of the GPS solution due to weak satellite constellation (Mao et al., 1999; Williams et al., 2004; Msaewe et al., 2017), signal interference (Williams et al., 2004; Wu et al., 2015) or cycle slip and re-convergence of the PPP solution (in case of one GPS-site only; Li et al., 2011). In the above cases, the local or site-specific anomaly observed in the GPS solution will be flagged but not as seismic motion. Furthermore, during the spatial search there is no correlation between the direction of the detected displacement of the GPS sites. Hence, there is no evaluation whether the detected displacement follow a specific patter, which would reflect the ground deformation due to a specific fault type (normal, strike-slip, etc.). Potentially, for specific GPS networks in an area of well-known and studied seismic faults, this correlation could be applied, limiting even further the false alarms.
Furthermore, Figures 7-9 furnish data in terms of peak elastic and inelastic response spectral ordinates to assess the potential of the HF+BOX and HF+COS models of Table 1 to yield structural responses com- parable to those obtained by the recorded PLGM considered to “calibrate” these stochastic models. Specifically, Figure 7 include elastic response spec- tral statistics for 5% critical damping ratio derived from the HF+BOX and HF+COS ensembles (200 realizations each) together with the elastic response spectra of the recorded PLGM of Figure 4. Further, Figure 8 includes similar plots in terms of constant ductility (μ=2) inelastic spectral ordinates assuming critically damped to 5% bilinear hysteretic oscilla- tors with pre/post-yielding stiffness ratio equal to 5%. Finally, Figure 9 plots the mean values of the response spectral ordinates of the HF+BOX and HF+COS ensembles including in the previous two figures normalized to the corresponding response spectral ordinates of the considered “target” re- corded PLGM according to the ratio (see also Fu and Menun 2004)
Some of these methods have been extended to simulate ground motion records by including the spatial coherency (Hao et al., 1989; Abrahamson, 1992) for uni-directional groundmotions at different sites. However, none of these methods considered the potential spatial correlation of ground-motion measures such as the FAS, even though the spatial correlation of ground-motion measures can significantly affect the estimated risk of spatially distributed building stocks (Goda and Hong 2008b). Moreover, structures and infrastructure systems such as irregular building with different dynamic characteristics in two horizontal directions and bridges with multiple supports can be sensitive to bi-directional and/or multiple-support excitations (Clough and Penzien 2003; Zerva 2009). The orientation of the records can also affect the characteristics of records and responses of the structures (Arias 1970, 1996; Penzien and Watabe 1975; Hong and Goda, 2010). Algorithms that incorporate both the spatial coherency and spatial correlation for simulating records with multiple components at multiple stations by considering scenario events are lacking.
Primarily the liquefactionpotential based on Idriss and Boulanger 2008, is evaluated using the factor of safety against the triggering of liquefaction. Daja, et al., 2011 have also evaluated the potential of liquefaction in this area by means of the liquefaction probability. Comparing the results of these two methods is one of the aims of the paper.
Because of friction and the rigidity of the rock, the rocks cannot slide or flow past each other. Rather, stress builds up in rocks and when it reaches a level that go beyond the strain threshold, the accumulated potential energy is dissipated by the relief of strain, which is focused into a plane along which relative motion is accommodated—the fault. Strain is both accumulative and instantaneous depending on the rheology of the rock; the ductile lower crust and mantle stores deformation gradually via shearing, while the brittle upper crust reacts by fracture - instantaneous stress release - to cause motion along the fault. A fault in ductile rocks can moreover release instantaneously when the strain rate is too great. The energy released by instantaneous strain release causes earthquakes, a common phenomenon along transform boundaries .
The result of the analysis of soil liquefaction is presented in Figure 7. No investigated point is categorized as totally safe. The unsafe zone of SPT-1 is found 10 m deep, whereas that of SPT-2 is found 4.5 m deep. The unsafe zone of SPT-3 is found 3–6 m deep. SPT-3 is clearly more vulnerable to liquefaction than the other SPTs even though the smallest PGAs were applied to SPT-3. This result indicates that in addition to PGA, soil resistance is the main factor that determines the vulnerability of liquefaction. This result confirms the findings of the studies conducted by Mase , Misliniyati et al. , and Monalisa , all of whom reported that liquefaction is likely at shallow depths along the coastal area of Bengkulu City. This result also verifies the likelihood of liquefaction occurring on loose and medium sandy soil along the coastal area. As liquefaction is possible at shallow depths of 0–9 m, building foundations must be carefully designed, especially for buildings with more than two stories.
While prediction of the occurrence of surficial manifesta- tion is an important component of liquefaction hazard analy- sis, the severity of manifestation is of greater consequence to the built environment and is thus of added importance for hazard mapping and engineering design. To investigate the capacity of each LPI model for predicting manifestation severity, additional ROC analyses were performed for each classification of severity in Table 1; the results are sum- marised in Table 2 in the form of AUC and recommended threshold LPI values. Where the prior ROC analysis assessed each model’s capacity for predicting any surficial manifesta- tion (i.e. having at least marginal severity), the additional analyses assess their ability to predict that manifestations will be of a particular severity (e.g. moderate as opposed to marginal). As mentioned previously, lateral spreading is treated separately in this study, and the ‘marginal’, ‘moder- ate’ and ‘severe’ classifications refer only to sand-blow manifestations. This distinction is made because lateral spreading is a unique manifestation associated with large permanent ground displacements, and because there are separate criteria for assessing its severity (e.g. Youd et al., 2002), including the ground slope and height of the nearest free face (e.g. river bank), among others. Consequently, although site profiles with thin liquefiable layers may have low LPI values, these sites are susceptible to lateral spread- ing if located on sloping ground or near rivers. Since the factors pertinent to lateral spreading cases are not considered in the formulation of LPI, such cases should not be used to assess its performance.
A scaling method similar to “range” scaling that operates over a period range is termed as Geometric Mean Scaling Method. It was developed for offshore oil industry and utilized in the SAC Steel Project (1997). The method involves multiplying the entire suite of groundmotions by a single factor such that the sum of the squared errors between the target UHS and the geometric mean of spectral ordinates for each ground motion will be minimized. The target periods are selected by users (Huang et al., 2009). The scale factor associated with the minimum squared errors is usually obtained from iterative calculation. This method preserves the spectral acceleration shape and original dispersion of unscaled groundmotions. A good match is determined by careful ground motion selection mechanism; meaningful results are obtained when both the median spectrum acceleration and dispersion of groundmotions match well with corresponding targets are guaranteed. However, ensuring both requirements in most cases is quite impractical and sometimes not possible. The plot of geomean scaled case is shown in Figure 12. It must be noted that the plot is the same as that in the unscaled case shown in Figure 9.
Attention to the significant differences of near and far- field ground motion has been raised by various researchers in the past. These differences could be summarized in two main characteristics named “rupture directivity” and “fling step” observed in near-field groundmotions. Directivity phenomenon could be demonstrated in the form of forward, backward and neutral effect depending on direction of rupture propagation. In case of forward directivity, the most of seismic energy radiated from the source appears as a distinct strong pulse in the ground motion perpendicular to the fault strike. Much evidence of such effect as a basic attribute of near-field groundmotions has been reported in recent destructive earthquakes 1978 Tabas, Iran; 1995 Kobe, Japan; 1999 Chi-Chi, Taiwan; 2003 Bam, Iran and 2009 L’ Aquila, Italy [1-4].
Trifunac MD, Lee VW (1985). Preliminary empirical model for scaling Fourier amplitude spectra of strong ground acceleration in terms of earthquake magnitude, source to station distance, site intensity and recording site conditions, Report CE 85-03, Dept. of Civil Eng., U. So. California, Los Angeles, California.
The intensity of ground shaking produced by an earthquake can be assessed using both quantitative and qualitative measures. While seismographic instruments record the velocity or acceleration of ground movement, the strength of ground shaking may also be described by its physical manifes- tations: human reactions to the shaking, the behaviour of furniture or other free-standing objects, damages to buildings and infrastructure, or visible surface waves, to name a few. Quantitative ob- servations of groundmotions are ideal, as these give accurate and precise measures of ground shak- ing. But seismometers are sparsely located in some regions, especially those with less-frequent severe earthquakes. But while extensive seismographic coverage may not exist in many regions (for instance Eastern North America), Internet-based earthquake reporting by citizens makes it easy to rapidly obtain large numbers of qualitative observations. Citizens can now easily report information about earthquake ground shaking and its physical e ff ects, which can then be processed into a value of Modified Mercalli Intensity (MMI). This value summarizes the observed intensity of ground shaking over a given geographical area. Making use of this readily obtainable and rich data can enhance our understanding of groundmotions in regions where instrumental coverage is limited, or for historical earthquakes where such instrumental data is altogether absent.
The materials present in Chapters 2, 3, and 4 of this thesis have been previously published or submitted for publication to the peer-reviewed journal of Bulletin of Seismological Society of America. This thesis contains only the original results of research conducted by the candidate under supervision of his mentor. The original contributions are summarized as follows: Compilation and data processing of ground-motion time series for selected earthquakes in Italy, New Zealand and Turkey; Calculation of Fourier acceleration spectra and the closest rupture distances for groundmotions studied in Chapter 2; Compilation of seismological parameters as well as peak groundmotions and response spectral amplitudes from NGA- West2 and NGA-East flatfiles for the study events in Chapters 3 and 4; Determination of predicted motions from NGA-West1 and NGA-West2 GMPEs; Regression analysis and statistical analysis of residuals; Stochastic equivalent point-source simulations; Analysis of modeling trade-offs and determination of ground-motion saturation parameter; Calculation of stress parameters and simulation calibration factor for California events; Determination of model coefficients for the generic GMPE and its adjustment to the central and eastern North America.
3) The multiplier of CSO sector in general shows the average values higher than the petroleumr efineries products sector. These values indicates that the synthetic coal oil sector has the potential to create a new output that capable to drive the national economic sectors equivalent to the petroleum refining sector and other energy providers. However, this sector has a surplus multiplier value is lower than other energy providers sector who indicates that CSO plant investment is less able to provide operating surplus that attractive to investors.
Abstract — This paper presents prediction of liquefactionpotential of soils by neuro-fuzzy models evaluated using Idriss and Boulanger method. In order to address the collective knowledge built up in conventional liquefaction method, an alternative Takagi-Sugeno-Kang reliant neuro-fuzzy model has been developed. Neuro-fuzzy is one of the artificial intelligence approaches that can be classified by machine learning as it is a robust and flexible method and may easily be adopted. Idriss and Boulanger method used for evaluation of liquefactionpotential of soils for its better estimation capability compared to other conventional methods. To estimate the liquefactionpotential bore log data were obtained from SPT tests conducted at sites. Hundred ten datasets from fifty boreholes up to a depth of ten meters were collected for training neuro-fuzzy models whereas twenty six datasets were reserved for validating the models. The predicted results of neuro-fuzzy models compared with Idriss and Boulanger method advocate that trained neuro-fuzzy models are capable of predicting liquefactionpotential adequately.