Abstract




 
   

IJE TRANSACTIONS C: Aspects Vol. 31, No. 12 (December 2018) 2016-2021   

PDF URL: http://www.ije.ir/Vol31/No12/C/4-2948.pdf  
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  ASSESSMENT OF STRUCTURE-SPECIFIC FRAGILITY CURVES FOR SOFT STOREY BUILDINGS IMPLEMENTING IDA AND SPO APPROACHES
 
F. Mohamed Nazri, C. Kian Yern, M. Moffed Kassem and E. Noroozinejad Farsangi
 
( Received: June 12, 2018 – Accepted in Revised Form: October 26, 2018 )
 
 

Abstract    Soft storey building is popular due to the functional and aesthetic purpose, despite its weakness in resisting seismic excitation. Nonlinear Static (Pushover) Analysis (POA) is a time saving and simple assessment procedure prosposed in Eurocode 8 (EC8). However, its reliability in designing structure still remains a question. At the first stage, seismic performance of several building models using POA in EC8 is assessed. Later on, empirical accuracy of fragility curves generated by POA (using SPO2FRAG software) is studied and verified through Incremental Dynamic Analysis (IDA) results. Four models of regular and soft storey frame of 5- and 11-storey varying heights were designed according to Eurocode 2 (EC2) and (EC8). The simulation is performed in a NL platform to carry out POA and IDA. Capacity curve obtained is served as main input in SPO2FRAG software to generate fragility curve. Then, IDA is performed to generate IDA and fragility curves. Peak ground acceleration, PGA was converted into corresponding Sa(T1) using design spectrum from EC8. Performance levels of Life Safety (LS) and Near Collapse (NC) proposed by Vision-2000 have been the main interest in this study. Results shown that the base shear calculated by using Lateral Force Method in EC8 is adequate. Fragility curve generated by SPO2FRAG, has good comformity with IDA-based fragility estimation for regular 5-storey model; however, some deviation is observed for soft storey model (5-storey). All 11-storey frames shown unsatisfactory match of fragility curves from what was generated by SPO2FRAG, compared to IDA results.

 

Keywords    Pushover Analysis; SPO2FRAG; Soft Storey Structure; Fragility Curve; Eurocode; Performance Level

 

چکیده   

ساختمان با طبقه نرم به علت اهمیت کاربردی و زیبایی شناخته شده است، به رغم ضعف آن در مقاومت در برابر تحریک لرزه‌ا‌ی. تجزیه و تحلیل غیرخطی استاتیکی (Pushover) (POA) صرفه‌جویی در وقت و روش ارزیابی ساده در Eurocode 8 (EC8) است. با این حال، قابلیت اطمینان طراحی این نوع سازه همچنان یک سوال باقی است. در مرحله اول، عملکرد لرزه‌ای چند مدل ساختمان با استفاده از POA در EC8 ارزیابی می‌شود. بعلاوه، دقت تجربی منحنی‌های شکنندگی تولید شده توسط POA (با استفاده از نرم‌افزار SPO2FRAG) از طریق تجزیه و تحلیل دینامیکی بارفزاینده (IDA) مورد بررسی قرار گرفت. چهار مدل از قاب منظم با طبقه نرم و ارتفاع 5 و 11 طبقه با توجه به Eurocode 2 (EC2) و (EC8) طراحی شده است. شبیه‌سازی در یک محیط غیرخطی برای انجام POA و IDA انجام می‌شود. منحنی ظرفیت به دست آمده به عنوان ورودی اصلی در نرم افزار SPO2FRAG برای ایجاد منحنی شکنندگی بکار گرفته شده است. سپس تحلیل دینامیکی بارفزاینده برای تولید منحنی‌های IDA و شکنندگی استفاده شده است. بیشینه شتاب زمین، PGA به (Sa (T1 مربوطه با استفاده از طیف طراحی EC8 تبدیل شده است. سطوح عملکرد ایمنی جانی (LS) و آستانه فروریزش (NC) پیشنهاد شده توسط Vision-2000 مورد توجه این مطالعه بوده است. نتایج نشان داد که برش پایه محاسبه شده با استفاده از روش نیروی جانبی در EC8 کافی است. منحنی شکنندگی تولید شده توسط SPO2FRAG، دارای سازگاری خوب با برآورد شکنندگی مبتنی بر IDA برای مدل معمول 5 طبقه است. با این حال، تا حدودی اختلاف در سازه با طبقه نرم (5 طبقه) مشاهده شده است. نتایج تمامی قاب‌های 11 طبقه نشان‌دهنده‌ی عدم مطلوبیت منحنی‌های شکنندگی تولیدی با SPO2FRAG در مقایسه با نتایج واقعی تحلیل IDA است.

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