فهرست مطالب

نشریه مهندسی عمران و محیط زیست دانشگاه تبریز
سال چهل و سوم شماره 3 (پیاپی 72، پاییز 1392)

  • تاریخ انتشار: 1392/10/01
  • تعداد عناوین: 8
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  • حمید شعبانی، یوسف حسین زاده* صفحه 1
    در طراحی قاب های فولادی با مقاطع متغیر، تحلیل سازه با فرض ابعاد اولیه برای اعضا انجام شده و پس از تحلیل با توجه به توزیع نیروهای داخلی، مقاومت و پایداری اجزای سازه، طرح اولیه اصلاح می شود. آزمون و خطا به صورت تحلیل مجدد قاب با ابعاد اصلاح شده و اصلاح دوباره ابعاد پس از تحلیل، تا یکسان شدن مقاطع طرح شده با مقاطع به کار رفته در تحلیل تکرار می شود. تعداد زیاد متغیرهای آزمون و خطا یعنی ابعاد مقاطع متغیر و طول ماهیچه اعضا، سبب می شود که در مواردی پس از صرف زمان قابل توجه، طرح نهایی به جوابی غیر از اقتصادی ترین جواب برسد. در این مقاله از الگوریتم های ژنتیک و میکروژنتیک برای رسیدن به طرح بهینه و اقتصادی قاب های فولادی با مقاطع متغیر استفاده شده است. نرم افزاری برای تحلیل خطی، طراحی و بهینه سازی قاب های فولادی با مقاطع متغیر و با استفاده از الگوریتم های ژنتیک و میکروژنتیک تهیه شده است. وزن سازه به عنوان تابع هدف و نسبت تغییرمکان نسبی طبقات، تنش اعضا و اندرکنش نیروی محوری و لنگر خمشی، به عنوان قیدهای طراحی در نظر گرفته شده اند. به کمک روش پیشنهادی، ابعاد بهینه اعضای قاب فولادی با مقاطع متغیر و طول بهینه ماهیچه قسمت های متغیر تعیین می شود. همچنین مزایای الگوریتم میکروژنتیک نسبت به الگوریتم ژنتیک و تاثیر نخبه گرائی الگوریتم ها در رسیدن به جواب بهینه بررسی شده است.
    کلیدواژگان: قاب فولادی با مقاطع متغیر، اعضای غیرمنشوری، بهینه سازی، الگوریتم ژنتیک، الگوریتم میکروژنتیک
  • محمد هوشمند*، بهزاد رافضی، جعفر خلیل علافی صفحه 11
    آلیاژهای حافظه دار شکلی کاربردهای متنوعی در مهندسی سازه دارند. استفاده از این مصالح به عنوان میراگر در مهاربندها نمونه ای از کاربردها می باشد. هر چند تحقیق در مورد استفاده از این آلیاژها به عنوان میراگر بیشتر شده است، اما این میراگرها به دلیل داشتن هزینه های ساخت بالا، خیلی جنبه اجرایی به خود نگرفته و بیشتر حالت تحقیقاتی دارند. در این مقاله سعی شده است تا مهاربندهایی ترکیبی از جنس فولاد و آلیاژهای حافظه دار ارائه گردند. به طوری که این مهاربندهای ترکیبی، هم از لحاظ اقتصادی قابل توجیه باشند و هم از لحاظ عملکرد لرزه ای، رفتار قابل قبولی را داشته باشند. به همین دلیل از شش مدل مهاربند ترکیبی استفاده شده است که در این مدل ها میزان مصرف طولی آلیاژ حافظه دار به ترتیب صفر، 20، 40، 60، 80 و 100 درصد می باشند. برای ارزیابی مدل ها از تحلیل دینامیکی غیر خطی استفاده شده است که تحت زلزله ال سنترو مقیاس شده با شتاب های حداکثر 0.6g و 0.9g قرار گرفته اند و در نرم افزار ANSYS v11 مدل سازی و تحلیل گردیده اند. نتایج مطالعات انجام شده مقادیر بهینه استفاده از درصد مهاربند ترکیبی را ارائه می دهد. به طوری که می توان با استفاده از طرح ارائه شده، سازه هایی با رفتار لرزه ای مناسب و با هزینه ساخت قابل توجیه طراحی و اجرا نمود.
    کلیدواژگان: آلیاژهای حافظه دار شکلی، مهاربند ترکیبی، تحلیل دینامیکی غیرخطی، زلزله ال سنترو
  • امیرصمد قدس، محمدرضا اصفهانی* صفحه 23
    محاسبه فشار هیدرودینامیکی مهم ترین مسئله در تحلیل مخازن ذخیره آب می باشد. در آیین نامه های رایج، رابطه فشار هیدرودینامیکی بر روی بدنه مخزن با فرض صلب بودن دیوارها به دست می آید و در مدل دینامیکی مخازن اثر مایع به صورت یک جرم افزوده بر روی دیوارهای مخزن در نظر گرفته می شود. در این مقاله به منظور در نظر گرفتن اثر انعطاف پذیری دیوارها در محاسبه فشار هیدرودینامیکی و در تحلیل دینامیکی سازه، از یک روش پیشنهادی المان محدود به صورت حل گام به گام استفاده می شود. روش پیشنهادی این مزیت را دارد که تحلیل در هر شرایطی دارای پایداری عددی بوده و در آن فشار هیدرودینامیکی به عنوان بار خارجی در هر گام زمانی در طول تحلیل تاریخچه زمانی بر روی دیوار مخزن قرار می گیرد. در تحلیل، دیوارهای مخازن مستطیلی با مقاطع مختلف منشوری و غیر منشوری مدل شده و پس از تحلیل تاریخچه زمانی با روش پیشنهادی تحت شتاب افقی زمین، پاسخ های دینامیکی شامل تغییر مکان ها و فشارهای هیدرودینامیکی مورد بررسی قرار گرفته اند. برای مدل های مختلف، جرم افزوده از رابطه میان شتاب دیوار مخزن و فشار هیدرودینامیکی تعیین شد. نتایج تحلیل نشان می دهند که جرم افزوده و فشار هیدرودینامیکی تابعی از انعطاف پذیری دیوارهای مخزن می باشند. در آیین نامه ها نسبت میرایی برای مخازن خالی و پر مقدار ثابت 5% پشنهاد شده است. به منظور بررسی اثر این نسبت بر روی پاسخ های دینامیکی، مخازن با نسبت های مختلف میرایی تحلیل شدند که نتایج نشان می دهند مقدار نسبت میرایی اثر زیادی بر روی پاسخ های دینامیکی دارد.
    کلیدواژگان: انعطاف پذیری دیوارها، المان محدود، جرم افزوده، فشارهای هیدرودینامیکی، مخازن آب، میرایی
  • علی رسول زاده*، ندا نصیری صفحه 29
    کمبود منابع آب با کیفیت مطلوب موضوع حائز اهمیت در مناطق خشک و نیمه خشک بوده لذا استفاده از منابع آب با کیفیت نامطلوب مانند زه آب ها از اهمیت خاصی برخودار می باشد. در این تحقیق تاثیر استفاده مجدد از آب زهکشی شور بر روی ویژگی های هیدرولیکی خاک دشت مغان مطالعه گردید. این پژوهش با سه تیمار شامل تیمار 1 شاهد (آبیاری با آب کانال)، تیمار 2 (اختلاط 30% زه آب با 70% آب کانال) و تیمار 3 (اختلاط 50% زه آب با 50%آب کانال)، در سه تکرار در قالب طرح کاملا تصادفی انجام شد. نمونه خاک دست نخورده، توسط استوانه هایی به ارتفاع 50 سانتیمتر و قطر حدود 30 سانتیمتر برداشته شد. پس از یک سال آبیاری تیمارها، ویژگی های هیدرولیکی خاک با روش معکوس برآورد گردید. روش معکوس استفاده شده، بر اساس الگوریتم بهینه سازی لونبرگ- مارکوارت بوده و برای تخمین ویژگی های هیدرولیکی خاک در شرایط غیرماندگار با زبان برنامه نویسی C++ نوشته شده و همراه با مدل پیشرو HydroGeoSphere به عنوان کد عددی استفاده گردید. در بالای ستون خاک با استفاده از یک منبع متصل به باران سازکه قطرات آب تولید می کرد، بارش مصنوعی ایجاد گردید. میزان زهکشی آزاد، از انتهای ستون خاک جمع آوری و اندازه گیری شد. با توجه به بارش و زهکشی اندازه گیری شده، با روش معکوس هدایت هیدرولیکی اشباع (Ks) و پارامتر های منحنی مشخصه آب خاک ون گنوختن (α، β و rθ) که پارامتر های مجهول در محیط متخلخل غیراشباع می باشند، برآورد گردید. نتایج اعتبار سنجی نشان داد ویژگی های هیدرولیکی برآورد شده از دقت قابل قبولی برخوردار می باشند. نتایج تجزیه آماری نشان داد بیشترین حساسیت روش معکوس به پارامتر β نسبت به سایر پارامترها می باشد. استفاده از آب زهکشی، سبب کاهش معنی دار هدایت هیدرولیکی اشباع در تیمار سوم شده درحالی که اختلاف معنی دار بین تیمار های اول و دوم در سطح 5 درصد مشاهده نگردید. نتایج نشان داد که آبیاری با آب زهکشی در تیمارهای مختلف، سبب اختلاف معنی دار در ویژگی های معادله ون گنوختن در سطح 5 درصد نشد. نتایج نشان داد استفاده از آب زهکشی پس از یک سال سبب کاهش معنی دار هدایت هیدرولیکی در سطح 5 درصد در تیمار با نسبت اختلاط 50 درصد با آب کانال در مقایسه با شاهد شده است؛ اما در تیمار با نسبت اختلاط 70 درصد با آب کانال تاثیر معنی داری بر ویژگی های هیدرولیکی خاک رسی در منطقه مورد مطالعه نداشت.
    کلیدواژگان: زه آب، HydroGeoSphere، منحنی مشخصه آب خاک، هدایت هیدرولیکی خاک
  • علی فروغی اصل*، سید محمد جوادموسوی درچه ای صفحه 45
    ترک در سازه های بتنی به ویژه در سازه های هیدرولیکی از مشکلات اصلی این نوع سازه هاست. شیب دار بودن سازه ها مثلا در کانال ها و تونل ها نیز مزید بر علت شده و خسارات زیادی را تحمیل می نماید. عوامل مختلفی موجب پدید آمدن ترک ها به ویژه در سطوح شیب دار پوشش بتنی می شوند که یکی از مهمترین این عوامل، انتخاب نادرست اسلامپ مخلوط بتن با توجه به شیب بتن ریزی می باشد. در بتن ریزی ها، اسلامپ بالای بتن باعث شره کردن و عدم پایداری بتن بر روی سطح شیب دار شده در حالی که اسلامپ کم نیز موجب کاهش کارآئی و عدم تحکیم مناسب بتن می گردد. در این پژوهش با ارائه طرح اختلاط مناسب برای بتن و طراحی مدلی قابل تنظیم برای شیب های مختلف و به ابعاد100×600×1000 میلی متر سعی شده است که اسلامپ بتن های قابل اجرا در شیب های مختلف مشخص شده و با نمونه برداری از قسمت های مختلف سطح شیب دار و انجام آزمایش های گوناگون، خواص مکانیکی نمونه ها از جمله مقاومت فشاری، کششی و جذب آب مورد ارزیابی و مقایسه قرار گیرند. از نتایج قابل تامل در این پژوهش، علاوه بر تعیین مناسب ترین شیب به ازای نمونه های مختلف، کاهش مشخصات مکانیکی بعضی از پانل های بتن در قسمت پایین آن در مقایسه با قسمت بالای پانل در شیب بوده است که در صورت شره کردن بتن و سعی در نگهداری آن به وجود می آید و این می تواند دلیلی برای ایجاد ترک در بخش یک سوم پائینی شیب پانل ها به هنگام بهره برداری باشد.
    کلیدواژگان: رفتار بتن، بتن ریزی در سطوح شیب دار، پوشش کانال، پایداری بتن تازه، طرح اختلاط
  • عبدالرحیم جلالی*، آرش اکبری حامد صفحه 59
    مقیاس شدت زمین لرزه یکی از مشخصه های شتاب نگاشت ها می باشد که شدت یک زلزله را تعیین می کند. در این پژوهش دو نوع از مقیاس های شدت زمین لرزه ی اسکالر ارزیابی می شوند: تغییر مکان طیفی غیرارتجاعی (Sdi) و تغییر مکان طیفی غیرارتجاعی با ضریب مد بالاتر (IM1I&2E). این مقیاس ها برای ارزیابی عملکرد سازه ها تحت اثر زلزله های معمولی و نزدیک گسل مورد استفاده قرار می گیرند. همچنین می توان این مقیاس ها را به عنوان ضریب مقیاسی برای شتاب نگاشت ها مورد استفاده قرار داد. برای ارزیابی دقت پاسخ های محاسبه شده ی ساختمان ها تحت اثر زمین لرزه های نزدیک گسل، از دو پارامتر «کفایت» و «کارآیی» استفاده می شود. هدف اصلی این مطالعه بررسی کارآیی و کفایت این مقیاس ها نسبت به پارامترهای نزدیک گسل، بزرگی زلزله و فاصله تا گسل برای مدل های ساختمانی با سیستم های دوگانه و خمشی فولادی و بتنی 3، 9 و 20 طبقه می باشد. رکوردهای نزدیک گسل انتخاب شده در جهت عمود بر گسل دوران داده می شوند. سپس مدل های دو بعدی با استفاده از روش تاریخچه ی زمانی غیرخطی تحلیل می شوند. در این پژوهش، نسبت تغییر مکان نسبی به ارتفاع طبقه بیشینه به عنوان پاسخ سازه ای در نظر گرفته می شود. پس از محاسبه ی مقیاس های شدت زمین لرزه، برای ارزیابی کارآیی و کفایت آن ها به ترتیب از انحراف معیار پس ماندها و پارامتری به اسم p-value، که از تحلیل رگرسیون نتیجه می شوند، استفاده می شود. نتایج نشان دهنده ی این مطلب است که برای افزایش دقت، این مقیاس ها باید با پارامتر دیگری مورد استفاده قرار بگیرند.
    کلیدواژگان: عملکرد، کارآیی، کفایت، مقیاس شدت زمین لرزه ی اسکالر پیشرفته، زمین لرزه ی نزدیک گسل
  • شهاب کاوه کار، محمد علی قربانی*، افشین اشرف زاده، صابره دربندی صفحه 69
    دریاچه ارومیه به عنوان یکی از بزرگ ترین دریاچه های ایران، مقصد نهایی مجموعه ای از رودخانه های شمال غرب کشور است. با توجه به تغییرات زیاد بارندگی و همچنین تغییرات دمای هوا، تراز آب نوسانات زیادی داشته است. آگاهی از این نوسانات در بررسی مسائل مرتبط، از جمله ریسک پذیری تاسیسات و سازه های وابسته، تغییرات ذخیره آبی دریاچه، ساخت و سازهای ساحلی، محیط زیست و بسیاری از عوامل دیگر اهمیت دارد. روش های مختلف شبکه عصبی مصنوعی و برنامه ریزی بیان ژن برای پیش بینی سطح آب دریا ها کاربرد دارند. ساختار درختی کروموزوم ها در روش برنامه ریزی بیان ژن، این الگوریتم را به ابزاری قوی و مناسب برای حل مسائل مدل سازی تبدیل می کند. در تحلیل حاضر از ساختار درختی برنامه ریزی بیان ژن و همچنین از شبکه عصبی مصنوعی برای پیش بینی نوسانات سطح آب در مقیاس های زمانی مختلف در نه ترکیب متفاوت، شامل مقادیر نوسانات تراز آب یک تا نه روز قبل به صورت ورودی در نظر گرفته شد تا بهترین حالت ممکن جهت پیش بینی انتخاب و ساختار درختی مدل بهینه معرفی گردد. پیش بینی ها با استفاده از داده های نوسانات تراز آب دریاچه ارومیه انجام پذیرفت و تراز سطح آب در دوره زمانی آذر 1375 تا آذر 1386 برای شبیه سازی به کار گرفته شد. نتایج حاصل، حاکی از دقت مطلوب برنامه ریزی بیان ژن در شبیه سازی نوسانات سطح آب می باشد و مدل های درختی حاصل، شامل سه زیر درخت (ژن) در مقیاس روزانه در جدولی ارائه شده است.
    کلیدواژگان: برنامه ریزی بیان ژن، دریاچه ارومیه، ساختار درختی، شبکه عصبی مصنوعی، نوسانات سطح آب
  • رحیم یدالهی، یحیی همزه*، شادمان پورموسی، علیرضا عشوری، محمد جعفری، کامبیز راشدی صفحه 77
    به منظور کاهش مشکلات زیست محیطی و ایجاد ارزش افزوده در پسماندهای جامد حاصل از جوهرزدایی کاغذ، پانل های سیمان - پسماند با سه نسبت پسماند به سیمان شامل 2 به 3، 1 به 1 و 3 به 2، چسب بتن به عنوان افزودنی در سه سطح 0، 10 و 15 درصد وزنی پسماند و کلراید کلسیم به عنوان افزودنی در دو سطح 0 و 5 درصد وزنی سیمان ساخته شد. برای هر تیمار حداقل سه تکرار انجام شد و خواص پانل ها شامل چگالی، مدول الاستیسیته، مدول گسیختگی، چسبندگی داخلی، جذب آب، واکشیدگی ضخامت، مقاومت کشش پیچ و مقاومت در برابر آتش مورد ارزیابی قرار گرفت. نتایج نشان دادند که مقاومت خمشی و چسبندگی داخلی با افزایش مقدار پسماند کاهش می یابد و حداکثر این مقاومت ها در مقدار پسماند 40 درصد حاصل شد. اثرات نامطلوب پسماند بر خواص مذکور احتمالا ناشی از کم بودن قدرت اتصال پسماند در مقایسه با سیمان است. مقاومت کششی پیچ پانل ها kPa 7/22 اندازه گیری شد و جذب آب و واکشیدگی ضخامت پانل ها با افزایش مقدار پسماند به طور قابل ملاحظه ای افزایش یافت. با افزایش چگالی پانل ها، کاربرد چسب بتن و کلراید کلسیم همه خواص مورد بررسی مطلوب تر شدند. به طور کلی، در شرایط40 درصد پسماند، 10 درصد چسب بتن و مقدار 5 درصد کلرید کلسیم، پانل هایی با چگالی حدود 8/0 گرم بر سانتیمتر مکعب قابل تهیه است که مناسب ترین خواص را به لحاظ مدول های خمشی، چسبندگی داخلی، سختی و واکشیدگی ضخامت نسبت به پانل کناف گچی موجود در بازار داشته باشند. جذب آب پانل های ساخته شده در این شرایط با جذب آب کناف گچی برابر بوده ولی واکشیدگی ضخامت آن به طور قابل توجهی از کناف گچی کمتر است. همچنین مقاومت در برابر آتش این پانل ها به طور قابل توجهی از پانل کناف گچی بیشتر بود.
    کلیدواژگان: کاغذ بازیافتی، جوهرزدایی، پسماند، پانل سقفی، چسب بتن، خواص مقاومتی، مقاومت در برابر آتش
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  • Hamid Shabani, Yousef Hosseinzadeh * Page 1
    1.
    Introduction
    The steel frames with variable cross sections in large span bridges and industrial buildings are preferred due to economic considerations. In these frames, the distribution of internal forces depends on the assumed initial dimensions for cross sections of members. Based on the determined internal forces from initial structural analysis, ratio of the demand to capacity and the allowable story drift, section dimensions of the members are corrected. New analysis and design of the frame is performed with the dimensions for cross sections of members. Analysis and design are iterated until designed and assumed cross sections become the same. The aim of the trial and error method in assuming the initial dimensions, analyzing and designing of the structure is a safe structure design with minimum structural weight. Therefore, final plan is prepared after numerous iterations. The plan may be resulted in non- optimized design in some cases because of the large number of design restraints and variables, complicated distribution of internal forces and initial assumption. Therefore, it is necessary to devise an optimization method for designing such frames. In the current study, the genetic and micro-genetic algorithms were used to find an optimized design with minimum weight of steel frames having variable cross sections members. The aim of these optimization methods was selection of the proper cross sections to obtain a safe design with considering the strength and serviceability criteria of building specifications. The studied frames have been built from the welded variable cross section beams with compact web and flange components. 2.
    Methodology
    A software in Fortran language was prepared for linear analysis, optimization and design of steel moment frames with non-prismatic members by use of genetic and micro-genetic algorithms. This software is capable to use all of the genetic and micro-genetic algorithms parameters. Also, it can consider any type of loading and boundary conditions. The structure weight is regarded as the objective function and the ratio of the story drift, axial force; bending moment and member stress are the restraints. The optimum dimensions of the member sections and the haunch length of the members with variable cross sections were determined using the suggested method. Therefore, the optimum design with minimum weight was obtained by eliminating the long steps of the trial and error method for searching the optimum sections of the structures with variable cross sections. The advantages and disadvantages of both algorithms were compared together with the obtained optimum designs and the effect of elitism to reach an optimum was examined. 3.
    Results And Discussion
    The genetic and micro-genetic algorithms were converged to identical designs after 100 and 95 generations in the frame under-study (Fig. 1), respectively. As shown in Fig. 2, the convergence rate in micro-genetic algorithm is higher than genetic one. The differences between minimum and maximum weights in genetic and micro- genetic algorithms were 7.35% and 5.27%, respectively. The use of genetic and micro-genetic algorithms with elitisms option led to decreased weight of the optimized frame.4.
    Conclusions
    As two efficient search methods, the genetic and micro-genetic algorithms are used for finding optimum design of steel moment frames with non-prismatic members. The results showed that the micro-genetic algorithm is preferred to genetic algorithm to find optimum design of steel frames with non-prismatic members. It has high convergence rate. This algorithm needs less population for obtaining an optimized design compared with the normal genetic algorithm. The number of required iteration steps in micro-genetic algorithm is less than the other algorithm.A Software in Fortran language was prepared using genetic and micro-genetic algorithm for optimum design of steel frames with variable cross sections. In this software, the linear elastic analysis of the structure is performed by stiffness method. In the optimization process, the stress constraints are considered in the frame members to account interaction between axial forces and bending moments. In this procedure, the weight of structure is the objective function and the story drift, stress and the interaction between the axial force and bending moment are the constraints. The optimum cross sections and the length of the haunch of members with variable cross section were determined using the suggested method.The elitism application effect was investigated in the algorithms. The elite-oriented approach resulted in the improvement of the genetic and micro-genetic algorithm functions. The we of the elitism option in both algorithms led to the increased efficiency of the algorithms and decreased weight of the optimized frame. In these kinds of algorithms, regarding the decreased number of the new members, the convergence rate increases.
    Keywords: Steel frames with Non, prismatic members, Non, prismatic sections, Optimization, Micro, genetic algorithm, Genetic algorithm
  • Mohammad Hooshmand*, Behzad Rafezy, Jafar Khalil, Allafi Page 11
    1.
    Introduction
    Shape memory alloys (SMA) have found various applications in structural engineering such as active, semi active and passive control due to its characteristics such as high damping capacity, durability, resistance to fatigue and corrosion and its unique characteristics such as shape memory and superelasticity [1]. One of the most important and effective applications of SMA in civil engineering is using these materials as braces, because of the superelastic and shape memory properties of SMA. They have the ability to re-center the original state and to provide high energy dissipation. However, most of the researches about the use of shape memory alloys in structural engineering are in theory level and few of them are experimental.2.
    Methodology
    For the comparison of models, a three-story structure has been used which was proposed by Sabelli. Assuming symmetry in the plan, only a two-dimensional frame of the structure has been analyzed. The height of each floor is 3.96 m and the construction plan is 9.14 in 9.14 m. Ceilings of the floors are composite that the height of the steel part is 76 mm and the height of concrete cover is 50 mm. It is noteworthy that the axial deformation of the beam is ignored [2].The models used for this study are in such a way that bracings, a combination of steel and SMA, have the consumption of 0, 20, 40, 60, 80 and 100 percent respectively in which the first model is the model of steel brace and the last one is the model of SMA brace. A schematic of the bracing is shown in Fig. 1. 3.
    Results And Discussion
    There are two major differences between the behaviors of steel and SMA both of which are introduced as the special properties of shape memory alloys. One of the properties is that this alloy is able to return to its primary state after bearing a large strain; in other words, to minimize the horizontal displacement of the structure; and the other one is that it increases the strain energy in the structure. This section has attempted to provide the most optimum brace through comparing the graphs of the history of horizontal displacement and diagram of structural strain energy in all models, both in terms of SMA consumption and seismic behavior.Table 1. The comparison of the residual displacement of structure in the used bracing systems under the maximum acceleration of 0.6gResidual displacement of structure (mm) Considered model5.31 Bracing system SMA 0% and steel 100%1.46 Bracing system SMA 20% and steel 80%1.10 Bracing system SMA 40% and steel 60%0.93 Bracing system SMA 60% and steel 40%0.85 Bracing system SMA 80% and steel 20%0.84 Bracing system SMA 100% and steel 0%The use of SMA, resistant to earthquakes which has a maximum acceleration of 0.6g, has not a significant difference with steel and utilizing them is not economically justifiable since the entire capacity of the SMA is not properly used. To have a better understanding, hysteresis graph of steel and SMA bracings under maximum acceleration of 0.6g is shown in figs. 3 and 4, respectively. According to fig. (5), it is observable that in the presented models, an increase in SMA consumption increases the value of energy absorption and an increase in the intensity of earthquakes (from 0.6g to 0.9g) indicates this result more clearly. The main reason is due to the special properties of SMA. It means that the return of the structure to its primary state after unloading and resistance against fatigue both cause the hysteresis loops of SMA to be bigger than that of steel and it shows the higher ability of SMA in structure controlling and better energy dampering.To have a better comparison, figs. 6 and 7 show hysteresis graphs of SMA braces and steel braces under maximum acceleration of 0.9g. 4.
    Conclusions
    The performances of bracing containing 20, 40, 60, 80 and 100% of shape memory alloy and steel bracing have been studied. The seismic response of the braced frames are determined and compared to the braced frame with steel brace. The results indicate that the most suitable location for putting shape memory alloy is the ends of bracing. Also, the secondary moment which is produced in bracing at the connection with gusset plate has transmitted better by shape memory alloy than steel. The total capacity of these alloys is not used in records with maximum acceleration of 0.6g and there is no difference between the behavior of steel brace and alloyed brace. Therefore, it is not necessary to use alloyed brace in low-intensity of earthquake due to economic considerations. It is observed that using 20% SMA in the alloyed brace improves 54% in seismic performance by 54% while by using 100% SMA, the amount of improvement is 94% It is concluded that the application of bracing which contains 20% SMA, leads to the improvement of seismic performance without considerable increase in constructional cost.
    Keywords: Shape memory alloys, Combination braces, Nonlinear dynamic analysis, El Centro earthquake
  • Amir Samad Ghods, Mohammad Reza Esfahani* Page 23
    1.
    Introduction
    The dynamic response of liquid containers to the underground excitation has been studied intensively in recent years. In early investigations, the fluid response in rectangular liquid storage tanks was represented by impulsive and convective components [1]. The fluid was assumed to be incompressible and the container was assumed to have rigid walls. The Housner’s model [1] has been adopted in most of the current codes and standards for calculating the hydrodynamic pressures in concrete tanks. Very strong earthquakes in the United States and Japan caused heavy damage to many liquid storage tanks. It has become perfectly clear that the concept of a rigid wall could not be retained for further modeling, since the real tanks deform significantly under earthquake loads. Including the wall flexibility in a dynamic analysis requires a systematic knowledge and understanding of the fluid–structure free-vibrational characteristics. As a direct result, new models have been developed and different experiments have been conducted, taking into account the flexibility of the tank walls [2]. Studies on the seismic response of rectangular tanks are not adequate, while those concerning cylindrical tanks are numerous. The time-history analytical method has been used to obtain the dynamic response of fluid storage tank subjected to earthquakes [3]. 2.
    Methodology
    In this study, the procedure for computing hydrodynamic pressures in rectangular tanks is described. This procedure considers the effect of tank wall flexibility in determining the hydrodynamic pressures produced by the impulsive response. Based on a two-dimensional model of the tank wall, a dynamic time-history analysis is carried out to study the effect of wall’s thickness and damping ratio on the response. Six different models for the tank wall with different thicknesses and the same height are considered. The wall section in models 1 to 4 does not change along the wall height, while it varies in model 5. Model 6 is based on the lumped mass approach assumption adopted by current codes. 3.
    Results And Discussion
    The results of the analyses are compared with those obtained based on current design practice codes and standards which use a lumped mass approach. The effect of wall flexibility and damping ratio on wall displacements and base shears are also discussed. Fig. 1 shows the hydrostatic pressure versus tank height relationship for models 1 to 4 when the maximum base shear is reached. Fig. 2 compares the hydrostatic pressures of model 3 with model 5. Table 1 presents the maximum base shear due to the hydrostatic pressures, and the elevation of the resultant force for all models.Table 1. Base shear forces and the elevation of resultant forces for different models6 5 4 3 2 1 Model412.2 256.44 307.26 280.35 230.34 221.58 FB hyd (kN)4.2 4.73 5.31 5.06 5.19 5.22 hi(m)4.
    Conclusions
    This study considers the wall flexibility of liquid tanks in the dynamic analysis. The results of the analysis are compared with those obtained from the lumped mass approach adopted by current codes. The comparison shows that in most cases, the lumped mass approach overestimates the base shear. The effect of wall flexibility and damping ratio on wall displacements and base shears are also discussed. The results show that the wall flexibility has a major effect on the hydrodynamic pressure and the seismic behavior of liquid tanks and should be considered in design criteria of tanks.
    Keywords: Added mass, Damping ratio, Finite element, Hydrodynamic forces, Liquid storage tank, Tank flexibility
  • Ali Rasoulzadeh*, Neda Nasiri Page 29
    1.
    Introduction
    The shortage of water resources of good quality is becoming an important issue in the arid and semi-arid zones, hence using of water resources of marginal quality such as drainage water has become an important consideration. In this study, saline drainage water reuse effect on soil hydraulic properties was investigated in Moghan plain. This objective was examined by Levenberg-Marquart optimization algorithm [1] for inverse modeling to estimate some hydraulic properties of soil in transient condition along with forward model (HydroGeoSphere) as a numerical code to simulate water flow in unsaturated porous media based on Richard's equation. 2. Methodology2.1. Study area and experimental device: Study area is located at Moghan plain in northwest of Iran. Undistributed soil samples were taken by cylinders with inner diameter of 30 cm and height of about 50 cm. Treatments were T1 (irrigation with canal water), T2 (irrigation with mixture of 30% drainage water and 70% canal water) and T3 (irrigation with mixture of 50% drainage water and 50% canal water) at three replications in a completely random design. Artificial rainfall experiments were conducted on top of the columns and free drainage from the bottom of columns was measured in the laboratory. Rainfall intensity was controlled by a rotary pump connected to a raindrop maker that produces water drops. 2.2. Numerical model description: HydroGeoSphere solves the three dimensional modified form of Richard's equation for variably-saturated flow using a Galerkin finite element approach [2]. The finite element grid was generated automatically using the pre-processor GRID BUILDER [3]. Grid independency was implemented and the discretization in the vertical direction was yielded 1.5 cm. The intent of this discretization was to be able to resolve vertical water flow with precision. In this study, we developed an inverse method for estimating parameters based on Levenberg-Marquardt minimization algorithm in C++ programming language. Inverse model was used to estimate the saturated hydraulic conductivity (Ks), and soil water retention function parameters of van Genuchten (α, β, and θr) which were unknown parameters in the unsaturated porous media using measured artificial rainfall and free drainage.3.
    Results And Discussion
    Calibration periods showed that the estimated free drainage using the optimized parameters exhibits a good match with the observed free drainage for all treatments. Hence one could conclude that Richard's equation along with van Genuchten's retention functions can successfully describe the unsaturated water flow in the treatments. Statistical analysis showed that the calibration is sensitive to β more than the other parameters. The Ks decreased significantly in T3 (P < 0.05) but there was no significant difference (P < 0.05) between T1 and T2. The results showed that parameters of van Genuchten have not been changed significantly in all treatments with application of drainage water reuse at probability level of 50% (Table 1).Table 1. Estimated hydraulic properties of treatments (Ks: saturated hydraulic conductivity, θs: saturated water content, θr: residual water content, α and β: shape parameters)β α(cm-1) θr(cm3 cm-3) Ks(cm min-1) Treatment1.21a 0.005a 0.143a 0.220a* T11.20a 0.005a 0.140a 0.226a T21.22a 0.006a 0.150a 0.166a T3* Same letter in column indicates no significant difference (P < 0.05)4.
    Conclusions
    Due to hysteresis effect, soil water retention curve has two desorption and sorption branches. Ordinarily, the desorption curve is measured by gradually and monotonically extracting water from initially saturated samples in the laboratory [4]. But the sorption curve is essential for modeling water and solute transport in unsaturated porous media. To overcome these problems indirect methods such as inverse method can be used to identify the basic flow and transport parameters. Hydraulic properties were estimated by inverse method at three replications in a completely random design. Estimated hydraulic properties succeeded to reproduce the observed free drainage in the transient condition, indicating van Genuchten functions along with Richard's equation can be used to simulate water flow in the treatments. The results illustrated that irrigation with the mixture of 30% of drainage and 70% canal water (T2) did not affect soil hydraulic properties significantly (P < 0.05) in the fine texture soil of study area after one year.
    Keywords: Drainage water, HydroGeoSphere, Soil moisture characteristic curve, Hydraulic conductivity
  • Ali Foroughi, Asl*, Seyed Mohammad Javad Mousavi Page 45
    1.
    Introduction
    Various factors lead to the creation of cracks in the slope lining of canals and one of the most important factors is the insufficient value of slump according to the cross-slope of canal. Workability of concrete shows the condition of concrete to indicate of how easy or difficult to place and consolidate. Slump test is one of the workability tests to measure it [1, 2]. Currently in our country, the concrete canal lining is constructed without the use of vibration, thus use of concrete with higher slump helps to maintain its workability. On the other hand, because of placing concrete on a sloping surface, it is poured on the surfaces with high slump. Hence as a result, high slump value of concrete mix will be poured on the slope and low slump value causes inefficient consolidation; and maintaining of the workability and consistency of concrete on slope lining at the same time is necessary [3].2.
    Methodology
    This research investigated concrete slump values in different slopes according to workability and consistency of mixtures in lining. For this purpose, a steel mold with dimensions of 1000 × 600 × 100 mm has been made. Consistency showing the flowing ability of fresh concrete in slope lining depends on internal friction angle of aggregates, cohesion of cement mortar, coefficient of friction between the concrete and the contact surface, slope angle, and the length and thickness of the concrete panels.3.
    Results And Discussion
    Experiments show that if a concrete mix with low slump will stay unstable on a particular slope, concrete maintains its consistency and glides down over the surface without any segregation. However, if a concrete mix with high slump value stays unstable on a particular slope, concrete pours on the surface of slope with the segregation of mix. Compressive and flexural test of samples were done and the results were compared with control samples. The results of this research demonstrate the reduction of the value of mechanical properties occuring at the bottom of some concrete panels compared to the top of the slope when concrete samples glide down or pour on the slope and we have to try keep it stable. This may be a good reason to create cracks in bottom of the slope during the serviceability of canals.Comparison of samples separated from the panel and control samples has been presented in Table 1.Table 1. Comparison of samples separated from the panel with control samplesSample properties Average of control samples Average of samples separated from the panel Comparison of panel sample and control sample Control sample with the weakest characteristics Control sample with the best characteristicsTensile strength at 28 days (MPa) 8.14 6.13 24.7% reduction 7.97 7.25 Compressive strength at 28 days (MPa) 72.6 50.7 30.2% reduction 71.75 60.62Water absorption percentage 2.7 3.61 31.3% increase 2.86 3.144.
    Conclusions
    Stability of concrete on the slope is dependent on various factors such as internal friction of aggregates, cement mortar bonding, friction coefficient between the concrete and the lower surface, the angle of slope surface and the thickness of concrete panels. Comparing the control samples and panel samples demonstrated that even with the best execution, samples are not even close to satisfactory condition and it seems to be necessary to use vibration in canals concreting.
    Keywords: Concrete behavior, Slope lining, Concrete consistency, Slump test, Mix design
  • Abdolrahim Jalali *, Arash Akbari Hamed Page 59
    1.
    Introduction
    Earthquake intensity measures (IMs) are used in assessing the seismic performance of structures. They can also be considered as scale factors for recorded ground motions in incremental dynamic analysis. “Sufficiency” and “efficiency”, that will be estimated using linear regression analyses, are two criteria for examining the concluded accuracy of using IMs in the structural performance assessment. In this paper, two advanced scalar IMs, including inelastic spectral displacement (Sdi) and inelastic spectral displacement with a higher-mode factor (IM1I&2E), are investigated. This research is concentrated on the evaluation of efficiency and sufficiency of advanced IMs for near-fault ground motions. For this purpose, by conducting nonlinear time history analyses, maximum inter-story drift ratio () as main structural response is estimated. After estimating IMs, for the assessment of their efficiency and sufficiency with respect to M, R and or, via linear regression analysis, standard deviation of residuals and a parameter called “p-value” are used respectively. Here, M, R and or are moment magnitude, closest distance to the rupture and directivity parameters, respectively. 2. Methodology2.1. Building models and earthquake records: Under the hypothesis of a rigid diaphragm, a 2-D centerline model of each of the ten symmetric and regular reinforced concrete and steel moment resisting framed and dual system frame building models with 3, 9 and 20 stories, which have been designed with ETABS, is created for nonlinear analysis using SAP2000. Each model consists of two exterior and interior frames which are connected together with a rigid link at every floor (as an example, see Fig. 1). For reinforced concrete buildings, the shear walls are modeled as a column at the middle of the corresponding span. Also, in the members of reinforced concrete building models, longitudinal and confinement bars are modeled. Flexural hinges (M3), interactional axial-flexural hinges (P-M3) and axial hinges (P) are assigned at the ends of beams, columns and braces, respectively. The nonlinear analyses take into account P- effects. The hysteretic models that are considered for hinges at the ends of members constitute stiffness and strength deterioration. Mass and stiffness proportional (Rayleigh) damping are assumed, with a damping ratio of 5% specified at the fundamental period (T1) and at a period with modal participating mass ratio more than 90%.In this research, a suite of 31 near-fault ground motion records, which have forward-directivity effects and have been recorded on “stiff soil” or “very dense soil and soft rock”, are selected from the PEER strong motion database [1]. The ranges of moment magnitude (Mw) and closest distance to the rupture (Rclose) of these records are from 6.53 to 6.93 and from 0.07 to 21.68 km, respectively.2.2. Methods and theoryIn this research, the strike-normal component of the ground motion records are considered. For this purpose, by using the values of the strike of the faults, each near-fault ground motion records are rotated to the strike-normal direction using MATLAB.Following the idea and notation of Luco and Cornell [1, 2], definition of IM1I&2E can be expressed as in which refers to the nth mode participating factor for the story in which the first two mode square root of the sum of the squares (SRSS) estimate of occurs. Since yield displacement dy is required for estimating IM1I&2E and Sdi, therefore, first-mode nonlinear static analyses (pushover) are conducted for every model and by means of base shear-roof displacement diagrams, the values of dy are calculated. As expressed in Eq. (1), values of Sd(T1,), Sd(T2,), Sdi(T1,, dy) and modal participation factors are required for estimating IM1I&2E and Sdi. The values of linear and nonlinear spectral displacements for a single-degree-of-freedom model with the values of T1, T2,, and dy are obtained using NONLIN.To estimate for every building model, nonlinear time history analyses are conducted by SAP2000. After performing nonlinear time history analyses and calculating IMs, for the assessment of sufficiency with respect to M, R and or, efficiency and bias of each IM for every building model, linear regression analyses using MATLAB are carried out. The efficiency of IM is measured by the degree of dispersion about the regression fit, and the sufficiency of IM is measured by the amount of statistical independency of the residuals, obtained from the regression of structural demand measure (DM) on IM, regarding M, R and or. In this research, for the evaluation of the efficiency and sufficiency of each IM, a one-parameter linear natural logarithmic regression is utilized. According to the attenuation relationships and equations which have been proposed by references [3] and [4], the employed regression model can be expresses as Where and c are the regression coefficients to be estimated and is the random error in given IM and M, R and or. The standard deviation of, indicated as is a criterion for assessing the efficiency of IM. The use of linear natural logarithmic regression is based on the roughly log-normal distribution of and invariable. If the coefficient c on M, R and or are not statistically significant, which can be computed by the equivalent p-value, then the given IM can be expressed as sufficient. The p-value is defined as the probability of finding an estimate of c at least as large (in absolute value) as that observed if, in fact, the true value of c is 0 [5]. Consequently, a p-value approximately less than 0.05 implies that the calculated coefficient c is statistically significant, and for this reason, IM is insufficient.3.
    Results And Discussion
    1) For 3-story reinforced concrete and steel buildings with dual system and moment resisting frames, both of the IMs are sufficient regarding M, R and or. However, due to the high standard deviation, they are not efficient. It’s due to that these buildings are low-rise then higher-mode effects are negligible and their behavior under the considered records are highly nonlinear; so, both of the IMs have acceptable results.2) For 9-story reinforced concrete buildings with dual system frame, despite Sdi has admissible sufficiency with respect to the considered 3 parameters, but it has high bias and standard deviation. The dispersion of the points around the line in Fig. 2 confirms the mentioned result. In addition to sufficiency with respect to M, R and or, IM1I&2E is efficient and it is the best choice for this kind of buildings. Also, it is noticed that the slope of the regression line is negative (as an example, see Fig. 4) and the dispersion of the points around the line for both of the IMs is the same and the value of the error for all of the considered parameters is in a small interval which respectively, show that c has a negative value and p-value is satisfying. However, for 9-story steel buildings with dual system frame, Sdi, despite sufficiency with respect to the 3 parameters, has relatively high bias and standard deviation. Also, IM1I&2E has high bias and standard deviation and does not supply sufficiency with respect to and. Then, because of high nonlinearity of this building under near-fault ground motions, applying Sdi is more appropriate than IM1I&2E.3) Due to high nonlinearity of the building under the records, for 9-story reinforced concrete and steel buildings with moment resisting frame, despite high bias, employing Sdi is more appropriate than IM1I&2E which does not supply sufficiency with respect to R.4) For 20-story reinforced concrete and steel buildings with moment resisting frames, Sdi has high bias and insufficiency with respect to R; but IM1I&2E supply both the efficiency and sufficiency. Then, the use of IM1I&2E for this kind of structures is more appropriate and the reason is low-nonlinearity and higher modes contribution in building’s behavior.4.
    Conclusions
    Based on the results of the current research work, the following conclusions are drawn:1) Both of the IMs supply the sufficiency with respect to M.2) For supplying the sufficiency of with respect to the directivity parameters (or), Sdi is proper.3) For supplying the sufficiency of with respect to R, Sdi is proper.4) For providing less bias and standard deviation for, IM1I&2E is appropriate.5) Eventually, it can be concluded that Sdi is more appropriate than IM1I&2E; however, for increasing the accuracy and supplying efficiency and sufficiency for each case, this IM must be considered with other parameters (e.g. spectral shape parameters) like vector IMs.
    Keywords: Performance, Efficiency, Sufficiency, Scalar intensity measure, Near, source ground motion
  • Shahab Kavehkar, Mohammad Ali Ghorbani*, Afshin Ashrafzadeh, Sabereh Darbandi Page 69
    1.
    Introduction
    Water level variations are highly sensitive to many environmental factors, such as lunar and solar gravitational attraction, waves and currents, atmospheric pressure and wind forcing, as well as many other dynamic presumably nonlinear and interconnected physical variables. Prediction of future water level heights in the coastal environment is of great importance for the protection of low-lying region's residents, for monitoring and prediction of changes in fishery and marine ecosystems. Different methods are used for water level prediction including time series analysis, fuzzy logic, neuron fuzzy, genetic programming, artificial neural networks, and recently, chaos theory [1]. Since the 1990s, time series methods employing the Genetic Expression Programming (GEP), Artificial Neural Network (ANN) and fuzzy logic methods have become viable, giving rise to the publication of many scientific studies [2]. This paper aims the application of GEP and ANN models to forecast sea level time series, which are data-driven modeling approaches.2. Methodology2.1. Study area and data: In this study, water level data was obtained from the Local Water Organization of Tabriz, Iran. Figure 1 shows the Urmia Lake located at latitude 40.35° North and longitude 13.44° East. Daily sea-water level measurements from January 1997 to July 2008 were used for training and validation of GEP and ANN models. The range of recorded values is from 1272.55 m (Jul, 2008) to 1277.77 m (June, 1997) with respect to above sea level. However, in a normal year, the range of level fluctuations does not exceed 87 cm. The initial time series data of was levels was obtained at a daily interval.2.2. Genetic expression programming: The GEP is similar to Genetic Algorithm (GA) but employs a “parse tree” structure for the search of its solutions, whereas the GA employs bite strips. The technique is truly a “bottom up” process, as there is no assumption made on the structure of the relationship between the independent and dependent variables but an appropriate relationship is identified for any given time series [3]. The relationship can be logical statements or it is normally a mathematical expression, which may be in some familiar mathematical format or it may assemble a mathematical functions in a completely unfamiliar format [4].3. Results and discussion3.1. Time series plots of predicted and observed values: Both the GEP and the ANN models were implemented using the recorded data at Urmia Lake, Iran. The record covering the years from 1997 to 2008 was divided into the period from 1997 to 2006 to train model and from 2007 to 2009 to verify it. GeneXpro software was used to implement the GEP model with the initial parameters. Fig. 1 show the recorded and simulated values and their scatter plot.Table 1 shows the results of each model. It can be seen that the Genetic Programming in general have smaller RMSE values than the Artificial Neural Network model for validation period and the correlation coefficient is high for the Genetic Expression Programming is higher than ANN model.Table 1. Statistical analysis of forecasted values with GEP and ANN methods R2 RMSE(m) Model0.997 0.0136 Genetic Programming0.996 0.0156 Artificial Neural Network4.
    Conclusions
    The GEP and ANN were used for forecasting water level variations in Urmia Lake, Iran. This study used GeneXpro and the results were compared with those from the ANNs by Qnet software. The mathematical modeling techniques for the analysis of time series were diversifying and this paper compared the performance of two such techniques. The GEP seemed to perform marginally better for most of the cases. The results seemed to support the emerging consensus that a single modeling technique is unlikely to render the solution. Instead, a set of solutions using different parameters and different simulation techniques is likely to identify the variability of the problem and the solution should be conditioned by the variability.
    Keywords: Artificial neural networks, Expression tree, Genetic expression programming, Urmia Lake, Water, level variation
  • Rahim Yadollahi, Yahya Hamzeh*, Shademan Pourmousa, Alireza Ashori, Mohammad Jafari, Kambiz Rashedi Page 77
    1.
    Introduction
    Large volume of sludges generated in pulp and paper industry causes environmental concerns and due to limited space and new legislations, their disposal options become more limited and uneconomical. Pulp and paper mill sludges, especially deinked paper sludge contains fundamentally non-hazardous solid materials such as lingocellulosic fibers, ink and significant amount of papermaking fillers such as kaolin, clay, CaCO3, talc and silica [1]. As an eco-friendly and clean alternative to land fill, paper mill sludge can be used for the fabrication of lightweight fiber-cement panels in which mineral compounds of sludge behave like the ingredients of cement and sludge fibers work as effective reinforcing agents [2]. In order to reduce the disposal problem of papermaking sludge and enhance the properties of flooring panels, concrete, in this study an attempt has been made to examine the effect of deinked paper sludge on some physical and mechanical properties of the flooring panel.2. Methodology2.1. Experimental study: In this study, paper sludge (PS) originating from Latif Papermaking Co, Karaj, Iran was used. We had previously reported its chemical and morphological properties [1]. The binding agent employed was commercial grade of Portland cement, Type II and Calcium chloride (CaCl2) was used as cement setting accelerator. It was an analytical grade from Merk Co, Germany. To improve the adhesion of cement and PS, a concrete bonding adhesive from CEDEX, Iran, with trade name of CRB was used as binding agent. Flooring panels with the dimensions of 350 × 270 × 12 mm3 were formed using PS contents of 40, 50, and 60 wt%, adhesive dosages of 0, 10, and 15 wt%, and 0 and 5 wt% of calcium chloride as an accelerator. At least three replications were fabricated for each treatment, and some mechanical and physical properties of the boards were evaluated. Control samples contained neat cement and water.2.2. Physico - mechanical testing: Prior testing, all the boards were conditioned in a controlled room for 15 days at 25 oC and 65% RH to reach the equilibrium moisture content of 12%. Conditioned boards were sawn into test samples to determine the modulus of rupture (MOR), modulus of elasticity (MOE, DIN EN 610), hardness (HS, DIN EN 897), and screw withdrawal perpendicular to the surface (SW, DIN EN 320), internal bond strength (IB, DIN EN 319) and fire resistance according to BS-476: Part 12 in the dry condition. Three-point flexural testing was carried out using an Instron Universal Testing Machine 4486, with a span of 180 mm and cross-head, the bearer diameter of 25 mm and the loading speed of 10 mm/min. The dimensions of test samples for MOR and MOE were 310 × 50 mm2 and for other tests were 50 × 50 mm2 with nine replications for each treatment. Physical properties, namely water absorption (WA) and thickness swelling (TS) were evaluated based on DIN EN 317. At least three specimens of every board were tested to obtain a reliable average and standard deviation.3.
    Results And Discussion
    The density of boards varied from 0.77 to 0.99 g/cm3.The average measured values of bending modules of rupture and elasticity are plotted against the PS content in Fig. 1a. It can be observed that MOR and MOE properties were enhanced with increasing PS content from 40 to 60%. A further increase in PS content (60%) showed a reduction in the bending strength. After analyzing the broken pieces of the specimens, it was observed that some parts of the PS could not distribute uniformly in the matrix, and a portion of these PSs was clamped and placed in some points of the specimen containing 60% PS. The internal bond strength of the panels was found to be a maximum when PS content was 40% and further addition of PS increased the volume of fibers and reduced the volume of matrix causing lower bond strength (Fig. 1b). Moreover, the panels produced using 60% PS exhibited the highest water absorption (Fig. 1c), presumably due to the low density producing more permeable voids so that more water can be absorbed [3]. The samples exhibited satisfactory SW resistance of 22.7 kPa to make an acceptable connection loads for use as lightweight board materials. The boards also showed the addition of CaCl2 and cement adhesive could not considerably improve SW resistance (Fig. 1d). Increasing the PS content showed negative influence on fire resistance and increased weight loss due to wire. Like SW resistance, the addition of CaCl2 and cement adhesive reduced the fire resistance of panels.4.
    Conclusions
    Results showed that the bending and internal strengths of the specimens were decreased with an increase in the PS content, and the maximum values were obtained at PS loading of 40 wt%. The negative influence of PS content on the mechanical properties can be explained by the reduced bonding ability of PS compared to cement. Screw withdrawal values were up to 22.7 kPa. Water absorption and the thickness swelling of fabricated panels were considerably increased with increased content of PS. In general, all properties of the boards were improved when the adhesive and calcium chloride contents were increased. The results showed that an increase in board density improved the mechanical and physical properties. In general, the fabricated panels with 40% PDS, 10% concrete adhesive and 5% CaCl2 with a density of around 0.8 g/cm3 had the best properties taking into account the bending modulus, internal bonding, hardness and thickness swelling which were considerably better than those of commercially available gypsum boards. Compared to the commercial gypsum boards, the fabricated panels had lower thickness swelling, comparable water adsorption and higher fire resistance.
    Keywords: Recycled paper, Deinking, Solid waste, Flooring panels, Concrete adhesive, Mechanical properties, Fire resistance