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Validation of Real Seismic Records Sets for Nonlinear Dynamic Analysis of Structures Located in Lattakia City - Syria

شرعنة مجموعات من السجلات الزلزالية الحقيقية لاستخدامها في التحليل الديناميكي لمنشآت واقعة في مدينة اللاذقية - سوريا

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 Publication date 2016
and research's language is العربية
 Created by سراج جديد




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Structural design for seismic loading, which is traditionally done for most types of common structures by the means of equivalent lateral static loading or modal spectrum analysis, is no longer a preferred methodology for design of modern structures with complex topology and functionality under extreme loading scenarios. Nonlinear response history evaluation, on the other hand, 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. Therefor using and scaling real recorded accelerograms is becoming one of the most contemporary research issues in this field. Seismological characteristics of the records, such as earthquake magnitude, epicentral distance and site classification are usually considered in the selection of real records, as they influence the shape of the response spectrum, the energy content and duration of strong ground shaking, and therefore the expected demand on structures. After real seismic records selection it is necessary to scale these records to match the intensity of the earthquake expected for the site. Generally, scaling can be made by ground motions uniform scaling in time domain which is simply scaled up or down the ground motions uniformly to best match (in average) the target spectrum within a period range of interest. It’s an engineer’s job to find the best scaling factors to best match the target spectrum, which is a complex task, so we employed the Genetic Algorithm (GA) in finding them to achieve the best results. When testing the selected and scaled ground motions, it’s a standard procedure to use the nonlinear 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, basic methodologies for selecting and scaling strong ground motion time histories are summarized, the selection and scaling criteria of real time history records to satisfy the Syrian design code are discussed. The GA scaling procedures are utilized to scale 10 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, 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, yield strength reduction factor, R= 4.5, α=3% post-yield stiffness, a number of 700 runs of analysis are conducted. The results are described for elastic displacement D.


Artificial intelligence review:
Research summary
تناولت هذه الدراسة منهجيات اختيار وتقييس السجلات الزلزالية الحقيقية لاستخدامها في التحليل الديناميكي غير الخطي للمنشآت الواقعة في مدينة اللاذقية، سوريا. تم التركيز على استخدام الخوارزمية الجينية لإيجاد معاملات التقييس المثلى للسجلات الزلزالية بهدف مطابقتها مع طيف الاستجابة التصميمي السوري. تم اختيار عشرة مجموعات من السجلات الزلزالية، كل مجموعة تتكون من سبعة سجلات، وتم تقييسها باستخدام الخوارزمية الجينية. بعد ذلك، تم اختبار فعالية هذه السجلات من خلال التحليل باستخدام السجل الزمني لمنشآت وحيدة درجة الحرية. أظهرت النتائج أن استخدام الخوارزمية الجينية يقلل من التبعثر في الاستجابة الإنشائية ويثبت كفاية وفعالية السجلات المستخدمة. توصلت الدراسة إلى أن التحليل باستخدام السجل الزمني يعطي استجابات أعلى من الاستجابات الطيفية، مما يدل على دقة وفعالية الطريقة المقترحة.
Critical review
دراسة نقدية: تعتبر هذه الدراسة خطوة مهمة نحو تحسين دقة التحليل الديناميكي غير الخطي للمنشآت في سوريا باستخدام السجلات الزلزالية الحقيقية. ومع ذلك، يمكن توجيه بعض الانتقادات البناءة. أولاً، قد يكون من المفيد توسيع قاعدة البيانات المستخدمة لتشمل سجلات زلزالية من مناطق جغرافية متنوعة لضمان شمولية النتائج. ثانياً، يمكن أن تكون الدراسة أكثر شمولية إذا تم اختبار المنهجية على أنواع مختلفة من المنشآت وليس فقط على المنشآت وحيدة درجة الحرية. أخيراً، يمكن أن يكون من المفيد تضمين تحليل اقتصادي لتقييم تكلفة وفوائد استخدام الخوارزمية الجينية مقارنة بالطرق التقليدية.
Questions related to the research
  1. ما هي الأهداف الرئيسية لهذه الدراسة؟

    تهدف الدراسة إلى شرعنة السجلات الزلزالية الحقيقية المختارة وفق متطلبات الكود السوري وتقييسها باستخدام الخوارزمية الجينية، ومن ثم تقييم فعالية هذه السجلات من خلال التحليل الديناميكي غير الخطي للمنشآت.

  2. ما هي الخوارزمية المستخدمة في تقييس السجلات الزلزالية؟

    استخدمت الدراسة الخوارزمية الجينية لإيجاد معاملات التقييس المثلى للسجلات الزلزالية بهدف مطابقتها مع طيف الاستجابة التصميمي السوري.

  3. ما هي النتائج الرئيسية التي توصلت إليها الدراسة؟

    أظهرت النتائج أن استخدام الخوارزمية الجينية يقلل من التبعثر في الاستجابة الإنشائية ويثبت كفاية وفعالية السجلات المستخدمة، كما أن التحليل باستخدام السجل الزمني يعطي استجابات أعلى من الاستجابات الطيفية.

  4. ما هي التوصيات التي قدمتها الدراسة؟

    أوصت الدراسة باستخدام الخوارزمية الجينية في إيجاد معاملات التقييس الأمثل، وإجراء دراسة الاستجابة على نماذج حقيقية لاختبار النتائج التي تم التوصل إليها.


References used
[12]. HWAIJA, B. JDYD, S. “Selecting Real Seismic Records and Scaling it to Fit the Syrian Design Spectra using Genetic Algorithm” Journal of Al Baath University, Syria, Vol. 37, 2015.
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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.
In this study, basic methodologies of the GA and the scaling procedures are summarized, the scaling criteria of real time history records to satisfy the Syrian design code are discussed. The traditional time domain scaling procedures and the scali ng procedures using GA are utilized to scale a number of the available real records to match the Syrian design spectra. The resulting time histories of the procedures are investigated and compared in terms of meeting criteria.
After selecting real seismic records it is necessary to scale these records to match the intensity of the earthquake expected for the site. Generally, scaling can be made by ground motions uniform scaling in time domain which is simply scaled up or d own the ground motions uniformly to best match (in average) the target spectrum within a period range of interest. It’s an engineer’s job to find the best scaling factors to best match the target spectrum, which is a complex task, so we employed the Genetic Algorithm (GA) in finding those scaling factors to achieve the best results. Genetic Algorithms (GAs) are probably the best-known types of artificial evolution search methods based on natural selection and mechanisms of population genetics. These algorithms are often applied to large, complex problems that are non-linear with multiple local optima. The power of the genetic algorithms is inherent in its capability to adapt. In natural systems, species adapt to the environment through successive interactions and generations subject to the environment. After several consecutive generations, only those species that can adapt well to the environment survive and the rest disappear. In mathematical terms, individuals are analogous to problem variables and environment is the stated problem. The final generation of the variable strings that can adapt to the problem is the solution. In this study, basic methodologies of the GA and the scaling procedures are summarized and the scaling criteria of real time history records to satisfy the Syrian design code are discussed. The traditional time domain scaling procedures and the scaling procedures using GA are used to scale a number of the available real records to match the Syrian design spectra. The resulting time histories of the procedures are investigated and compared in terms of meeting criteria.
Geomorphological-chemical studying of hole phenomenon which taked place in KARKIT village (NE of Lattakia) at 11/2/2009,indicate that it was a result of karstic phenomenons in gypsum rocks,this karst is result of underground water drainage inaccordance with fissures direction In study region N025 .
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