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Register a new userGeneration of Synthetic Time Histories Functions Compatible with Syrian Response Spectra in Frequency Domain and Time Domain Applicable to Dynamic Analysis
توليد سجلات زمنية صنعية متوافقة مع طيف الاستجابة السوري في مجال التردد و مجال الزمن لتطبيقها في التحليل الديناميكي
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نايل محمد حسن( باحث )
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تم في هذا البحث مناقشة معايير الاختيار و التقييس لسجلات زمنية حقيقية لتوافق كود التصميم السوري. تم استخدام اجراءات التقييس في مجال الزمن و مجال التردد لتقييس عدد من السجلات الحقيقية المتوفرة لتلائم طيف الاستجابة السوري. تم تحري و مقارنة السجلات الزمنية الناتجة من ناحية مناسبتها كمدخل للتحليل بالسجل الزمني لحالات أبنية قائمة.
In this study, basic methodologies and procedures for generation synthetic time histories in time domain and frequency domain are summarized. These synthetic time histories are matching Syrian spectrum and compatible with wide range of buildings models and soil types according to the seismic parameters of Lattakia city. This paper will discuss the Selection and scaling criteria of three real time history records available in strong ground motion databases to satisfy the Syrian spectrum, and the suitability as input to time history analysis of civil engineering structures.
References used
ABRAHAMSON, N. A; SILVA, W. J. "Empirical response spectral attenuation relations for shallow crustal earthquakes", Seismol. Res. Lett. Vol. 68,1997, pp. 94-127
Al Atik, L. and Abrahamson, N. A., 2010, "An Improved Method for Nonstationary Spectral Matching,", Earthquake Spectra 26 No 3, 601-89
Azlan Adnan, Hendriyawan, Aminaton Marto, Masyhur Irsyam " Development of synthetic time histories at bedrock for Kuala Lumpur ", Proceedings of the 6th Asia-Pacific
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: Nonlinear response history evaluation is becoming a practical tool due to availability of high performance computing and recommendations of the new seismic guidelines, and due to the increase of available strong ground motion database. When testing
the selected and scaled ground motions, it’s a standard procedure to use the time history analysis to validate the results in terms of structural responses and their variation. this proves the efficiency of the presented procedure.
In this study the selection and scaling criteria of real time history records to satisfy the Syrian design code are discussed. Ten set of records have been selected and scaled, every set consists of seven records of available real records, to match the Syrian design spectra. The resulting time histories are investigated and compared in terms of suitability as input to time history analysis of civil engineering structures, by mean of time history analyses of SDOF systems which are conducted to examine the efficiency of the scaling method in reducing the scatter in structural response. The nonlinear response of SDOF systems is represented by bilinear hysteretic model. Assuming 5 different Periods, α=3% post-yield stiffness, a number of 700 runs of analysis are conducted. And a number of 280 runs of analysis are conducted for MDOF systems.
Response spectrum analysis and equivalent static analysis is widely used by
engineers and engineering offices to estimate buildings and structures response
to earthquakes. But performance based procedures to evaluate buildings and new
designs acco
rding to Syrian code and other international codes require response
analysis using smallest of earthquake records, where we can estimate
engineeringdemandparameters(EDPs)—
floordisplacements,storydrifts,memberforces,memberdeformations,etc.—
ofbuildingsandspecialstructuressubjectedtogroundmotions, consecutively to
verify required performance criteria.
Theserecordsshouldbeproperlyselectedandscaledincompliancewithsitespecifichazardconditionstoestimate
(EDPs) and ensure that they verify
―expected‖ median demands.
In this study, background, selection procedures compatible with Syrian
code, and review of most scaling methods were introduced. The structural
response was studied by comparing displacements due to response spectrum
analysis, scaled records using PGA, and synthetic time histories records in time
domain and frequency domain (generated according to Syrian response
spectrum). Tow three-dimensional models of real buildings in Lattakia city were
used as study cases, the results obtained by 20 analysis processes. The results
show that analysis using synthetic records compatible with Syrian code give
noticeably less displacements estimates comparing with response spectrum
analysis and analysis using records scaled by PGA scaling.
Design ground motions are typically prescribed by smooth response spectra. Engineers often prefer to use a time history that matches the target design spectrum rather than evaluate a structure for a sit of time histories that are representative of th
e target spectrum in an ensemble average.
Generally, scaling actual time histories to match a given design spectrum can be made by two preferred methods: First, ground motions uniform scaling in time domain which is simply scaled up or down the ground motion uniformly to best match the target spectrum within a period range of interest, without changing the frequency content. Second, spectral matching in time domain which produces only localized perturbations on both the time history and the its response spectrum, where small adjustments can be made to a time history to change its response spectrum from jagged to smooth, if done properly the resulting time history can be “realistic”.
The realistic nature of a time history should be judged in the time domain in terms of the non stationary character of acceleration, velocity and displacement, for that the effectiveness of the two methods is examined by applying them to adjust actual earthquake time histories to much the design spectra while minimizing perturbations on their characteristics.
The procedures are utilized to scale 15 set of records, every set consists of seven records of available real records to match the Syrian design spectra. The resulting time histories are investigated and compared in terms of suitability as input to time history analysis of civil engineering structures
Reliable tagging of Temporal Expressions (TEs, e.g., Book a table at L'Osteria for Sunday evening) is a central requirement for Voice Assistants (VAs). However, there is a dearth of resources and systems for the VA domain, since publicly-available te
mporal taggers are trained only on substantially different domains, such as news and clinical text. Since the cost of annotating large datasets is prohibitive, we investigate the trade-off between in-domain data and performance in DA-Time, a hybrid temporal tagger for the English VA domain which combines a neural architecture for robust TE recognition, with a parser-based TE normalizer. We find that transfer learning goes a long way even with as little as 25 in-domain sentences: DA-Time performs at the state of the art on the news domain, and substantially outperforms it on the VA domain.
Low frequency shadows is one of hydrocarbons indicators. It can be
detected by means of a time-frequency decomposition which can provide higher
frequency resolution at lower frequencies and higher time resolution at higher
frequencies. This is des
irable for analyzing seismic data, because the
hydrocarbons in reservoir are diagnostic at lower frequencies. we have carried
out such analyses with post-stack data sets on Fahda field which is located in
Aleppo uplift, it contains oil. Adding a frequency axis to a 2D seismic section
makes the data 3D axis. The comparison of the single frequency sections from
such 3D volume can be utilized to detect low frequency shadows. A
preferentially illuminated single frequency section at lower frequencies from
Fahda field, shows high amplitude low frequency anomalies beneath oil zones.
These anomalies disappear at higher frequencies.
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