بررسی تاثیر عملکرد تنش پوسته‌ها با استفاده از تئوری فنر معادل در بهینه سازی سوله‌های قوسی

نوع مقاله : علمی - پژوهشی

نویسندگان

1 دانشکده عمران، دانشگاه یزد، یزد، ایران

2 دانشیار، دانشگاه یزد، یزد، ایران

3 استادیار، دانشگاه یزد، یزد، ایران

چکیده

در این پژوهش تاثیر ورق پوشش سقف و عملکرد تنش پوسته‌ها در طراحی بهینه سوله‌های قوسی مورد بررسی قرار می‌گیرد. طبق عملکرد تنش پوسته‌ها، بخشی از نیروی افقی وارد بر سازه، توسط دیافراگم و بخشی توسط قاب تحمل می‌شود و قاب‌ها برای نیروی کمتر طراحی می‌گردند در نتیجه این عملکرد نقش اساسی در طراحی بهینه سوله‌ها خواهد داشت. تئوری فنر معادل، روش مورد استفاده برای طراحی این عملکرد در این پژوهش می‌باشد. جهت طراحی سریع و آسان سوله‌ها، با برقراری ارتباط بین نرم افزارهای Sap2000 و Matlab و استفاده از الگوریتم ژنتیک، نرم افزار طراحی سوله فراهم شده است که این نرم افزار با استفاده از ابعاد سوله و شرایط محیطی محل استقرار سوله، به هر دو روش تنش مجاز و عملکرد تنش پوسته‌ها به طراحی سازه با بهترین مقاطع می‌پردازد. توسط این نرم افزار هفت سوله قوسی با ابعاد دهانه، طول، تعداد قاب و ارتفاع ستون متفاوت با ضخامت پوشش سقف 5/0 و 7/0 میلی متر طراحی و عملکرد تنش پوسته‌ها در آن‌ها بررسی می‌شود. تابع هدف وزن سازه است و مسئله شامل 8 متغیر طراحی می‌باشد. بررسی نتایج این مقاله نشان می‌دهد که عملکرد تنش پوسته‌ها بیش از 20 درصد در کاهش وزن تاثیر دارد و میزان این تاثیر به ابعاد سازه وابسته است به طوریکه افزایش ارتفاع ستون‌ها حدود 10 درصد تاثیر این عملکرد را افزایش می‌دهد و افزایش دهانه سوله از تاثیر عملکرد تنش پوسته-ای بیش از 5 درصد می‌کاهد. افزایش تعداد قاب‌ها و تغییر طول سازه تاثیری ناچیز و در حدود 1 یا 2 درصد دارد. تغییر ضخامت ورق پوشش به اندازه 2/0 میلی‌متر، حدود 3 درصد در کاهش بیشتر وزن موثر خواهد بود.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Optimal design of curved portal frame with consideration of stressed skin action using the equivalent spring theory

نویسندگان [English]

  • afsaneh shahpouri arani 1
  • Behrouz Ahmadi-Nedushan 2
  • Hoseinali Rahimi Bondarabadi 3
1 Masters student, Faculty of Civil Engineering, University of Yazd, Yazd, Iran
2 Associate Professor, Yazd University, Yazd, Iran
3 Assistant Professor, Faculty of Civil Engineering, University of Yazd, Yazd, Iran
چکیده [English]

This article investigates the effect of the roof cover and the stressed skin action on the optimal design of curved portal frames. According to stressed skin effect, diaphragm is carrying part of the horizontal force of structure and the remaining part is carried out by the frames. Therefore, interior frames are designed for lower forces which, in turn, results in a lighter structure. Stressed skin effect is modelled using the equivalent spring theory. A program which links Sap2000 and genetic algorithm was developed that provides the best sections which result in the minimum weight of structure. Designs are performed by using the allowable stress design and stress skin effect. Seven curved portal frames with different span dimensions, lengths, number of frames and column heights are considered and optimally designed for roof cover with thickness of 0.5 mm and 0.7mm. The objective function is defined as the weight of the structure and the problem consists of eight design variables. The results show that consideration of the stressed skin effect results in a reduction of weight by more than 20% and that increasing the height of column results in 10% reduction of the weight. Moreover, it was observed that increasing the length of the span results in a 5% reduction in weight. Effects of increasing the number of frames and changing the length of the structure are negligible and are only about 1 or 2 percent of reduction in weight. Increase in the thickness of the roof cover sheet about 0.2 mm results in a decrease of the weight by about 3%.

کلیدواژه‌ها [English]

  • "Curved portal frames"
  • "Optimal design"
  • "Stressed skin effect"
  • "Equivalent spring theory"
  • "Genetic Algorithm"
[1] Alavi, Seyyed Sadegh, (2013), Applied reference modeling, Analaysis, and design of gable frames in SAP, Tehran, Noavar. (In Persian).
[2] Allwood, R.J, Chung, Y.S , (1985), An optimality criteria method applied to the design of continuous beams of varying depth with stress, deflection and size constraints, Computer and Structuers, 20(6), 947-954.
[3] Tam, T.K.H, Jenning, A, (1988), Optimal plastic design of frames with tapered members, Computer and Structuers, 30(3), 537-544.
[4] Saka, M.P ,(2003), Optimum design of pitch roof steel frames with haunched rafter by genetic algorithm, Computer and Structures, 81, 1967-1978.
[5] Mahdilotorkamani, Hamed, Habibi, Alireza, (2009), Optimized design of sloping steel frame with variable cross section, First National Conference on Engineering and Management of Infrastructures, Tehran, University of Tehran. (In Persian).
[6] Goldberg, DE, (1989), Genetic algorithm in search-Optimization and machine learning, New york(USA), Addison Wesley Publishing Company.
[7] McKinstary, Ross, Lim, James B.P, Tanyimboh, Tiku T., Phan, Douc T., Sha, Wei, (2015), Optimal design of long- span steel portal frame using fabricated beam, Journal of Constructional Steel Research, 104, 104-114.
[8] Issa, Honar k., Mohammad, Fouad A, (2010), Effect of mutation schemes on convergence to optimum design of steel frames, Journal of constructional steel Research, 66, 954-961.
[9] Brayan E.B , (1973), The stressed skin design of steel Building , Canstrado monographs, london , Crossby Locked Staples
[10] European ecommendation for the application of metal sheeting acting as a diaphragm-stressed skin design, Technical committee 7- Thin walled, cold formed steel in building, Technical working 7.5- Practical improvement of design procedures, (1995).
[11] Davies, J.Michael, (2006), Development stressed skin design, Thin-Walled Structures, 44, 1250-1260.
[12] Franssen, J.M , (1984), Particular points of elastic analysis of clad pitched roof portal frame structures, Thin-Walled Structures, 2, 165-174.
[13] Nagy, Z.N., Pop, A., Mois, I., Ballok, R., (2015), Stressed skin effect the elastic louding of Pitched roof Portal frames,
Eighth International Conference on Advances In Steel Structures, Lisbon, Portugal.
[14] Phan, D.T., Lim, J.B., Tanyimboh, T.T., Wrzesien, A.M, Sha, W., Lawson, R.M., (2015), Optimal deaign of cold- formed steel portal frames for stressed- skin action using genetic algorithm, Engineering of Structures, 93, 36-49.
[15] Publication No.360: Instruction for seismic rehabilitation of existing building, (2007), Management and Planning Organization, Office of Deputy for Technical Criteria Codification and Earthquake Risk. (In Persian).
[16] Publication No.325: Terms of design and calculation of industrial steel building, (2007), Management and Planning Organization, Office of Deputy for Technical Criteria Codification and Earthquake Risk. (In Persian).
[17] Darcy, Greg, (2005), Structural Behavioar of an Innovative Cold-formed Steel Building System, A thesis submitted to the school of civil engineering queensland university of technology inpartial fulfilment of requirments for the degree of doctor Philosophy.
[18] Abbas Naseri, Morteza, (2015), Multi-objective optimization of 2D and 3D truss structures with meta-heuristic swarm optimization algorithm, MSc Thesis, University of Yazd. (In Persian).
[19] Zahraei, Banafsheh, Hosseini, Seyyed Mossa, (2014), Genetic algorithm and engineering optimization, Tehran, Gothenburg. (In Persian).
[20] Grandhi, R.V., Venkayya, V.B , (1998), Sruetural optimization with frequency constraints, AIAA Journal, 26(7), 858-866.
[21] Azhari, Mojtaba, Mirghaderi, Seyyed Rasoul, (2011), Design of steel structures (Volume II), Esfahan, Arkan Danesh. (In Persian).
[22] INBC.(2008), Design and construction of steel structures, Tehran, Ministry of Housing and Urban Development, Iranian National Building Code, Part 10. (In Persian).
[23] INBC.(2008), Design loads for building, Tehran, Ministry of Housing and Urban Development, Iranian National Building Code, Part 6. (In Persian).