بررسی رو شهای مدل آویزان محاسباتی در یافتن فرم سازه های پوسته ای

نوع مقاله: مقاله پژوهشی

نویسنده

استادیار معماری، دانشکده هنر و معماری، دانشگاه تربیت مدرس، تهران، ایران.

چکیده

سازه های پوسته ای یکی از سیستم های نوین در معماری معاصر می باشند که واجد خصوصیاتی همچون کسب مقاومت از طریق فرم و ارتباط با فرم معماری هستند. این سازه ها بار دیگر مورد توجه قرار گرفت هاند. لذا مسأله فرآیند تعیین فرم آ نها به طور بارز مطرح شده و راه حل هایی ارائه و به کار گرفته شده تا فرم بهینه به دست آید. یکی از این روشها مدل آویزان معکوس است. این روش از قرن هفدهم به صورت فیزیکی به کار می رفته و سپس به صور محاسباتی شکل گرفته است. از این رو بررسی این شیوه ها در یافتن فرم، خصوصیات فرم بهینه و پیشنهاد روش های مناسب تر، جهت بهره برداری ضرورت می یابد. لذا اهداف، دستیابی به چگونگی شکل گیری روش های محاسباتی بر اساس مدل آویزان فیزیکی و فرآیند یافتن فرم در آن ها، نیل به ویژگی های فرم بهینه و تعیین راه حل های مناسب تر می باشد. روش های تحقیق توصیفی- تحلیلی و در پروسه » هر مرحله فرآیند فرم فیزیکی « تاریخی به کار رفته است. از بررسی ها استنتاج می شود که با سنجش نیاز به فرم رقومی، معادل هایی برای آ نها معین می شود. در این روش ها هم لزوم تعیین فرضیات و متغیرهایی مشخص می شود. چگونگی شبیه سازی بار خارجی، مصالح و شرایط مرزی نیز آشکار می شود. نحوه شبیه سازی مدل آویزان هم با استفاده از روش های نظری انجام گشته و چگونگی تبدیل کابل به قوس نیز باقی می ماند. فرم حاصله، فرم اولیه بهینه می باشد، جهت تثبیت فرم، نمونه هایی براساس چندین شیوه مورد آزمون قرار می گیرد، بدین گونه فرآیند یافتن فرم طی می شود. خصوصیات شکل بهینه مانند حداکثر سختی، رفتار غشایی، حداقل انرژی و غیره می باشد. گرچه روش های محاسباتی دقیق تر عمل می کنند، لکن تقریباً اکثر ویژگی های فرم آنها نظیر روش فیزیکی است و برخی مانند کم بودن کل انرژی و بهینگی تغییر مکان ها افزوده شده اند. بیشتر نتایج روش ها یکسان می باشند. تمام روش ها غیر از 3 و 1 و نیمی از 5 راه حل های مناسب تری جهت به کارگیری می باشند.

کلیدواژه‌ها


عنوان مقاله [English]

Study of Computational Hanging Model Methods forFinding the Form of Shell Structures

نویسنده [English]

  • Afsaneh Zarkesh
Assistant Professor of Architecture, Faculty of Art and Architecture, TarbiatModares University, Tehran, Iran.
چکیده [English]

Shell structures are among new and reliable structural systems in contemporary architecture with special characteristics such as gaining strength through form and interconnection with architecture form. They have attracted researchers once more in the present era from different aspects including stability, the new generation of shells and modern construction techniques. Therefore, because of their complicated behavior, the problem of finding and the process of determining their form have been obviously and specificallypropounded and some solutions have been presented and applied to achieve the proper and optimal form. One of important these methods is the inverted hanging model. This method has been physically applied in finding compressive structures form for a long time since 17th century which was used firstly in arches, vaults and domes; and led to a variety and complex designs and It has become one of the methods to determine proper and various forms for shell due to its appropriation to the sell. The physical hanging model has been used in construction of various and many buildings some of which has been standing after too many years. Afterward the model has been formed and continued numerically because of its benefits, specifically due to its natural. Hence, it necessary to consider and recognize these methods for application, specifically those belong to the recent decades and form most of these approaches, in order to finding form and the related optimum formcharacteristics and suggesting better computational methods. Therefore, the purposes of the study are to find out the way of computational methods formation, based on the physical hanging model and the process of findings form in the methods; achieving optimalcomputational form’s characteristics; access to numerical methods’ features and determine the more proper solutions. In this regard we used descriptive- analysis and historical research methods to recognize the way of formation of all computational methods, based on the physical model methods, aiming at answering the goals of finding structural form as well as finding more proper ways to be applied currently. Hence, the shell structures'characteristics which should be considered in designing are extracted and determined from their definitions. Then, the issue of "finding the structural form" is assessed, because its definition and application is in sell structures, and different methods of finding theirforms and their being targeted determine the methods are related to the reverse hanging model. Thereafter, the problem of "physical hanging model in finding the shell form" isconsidered to recognize the hanging model theory, applied materials, purpose of hanging model, process and effective factors in achieving the form as well as the method and way of such model making. The main point is the computational hanging model methods in inding the shells' form that concentrates on the attempts to respond the research questions in the recent decade. Finally, we should conclude based on the reviews and analyses. Data collection instruments were library and internet sources.According to the finding of the study, the process of finding the form in computationalmethod based on the physical methods is as following: The need for each step in physical form process is assessed during the numerical formprocess and their equivalents are considered through computed methods. In these methods,at the beginning of the process, also some assumptions and variables are determinedin theory language, quantitatively and more precisely. The way of simulating externalload, materials and bordering conditions are also revealed in the methods. The way ofsimulating the hanging model is also using theoretical methods and the way of convertingcable into the arch remains unchanged, but it obviously differs from the physical method. The achieved form is the optimum primary form of the shell. To fix the form, some cases are tested based on a few methods including. "comparison with shells made by famous people, in reality and in real scale", "determining the allowed limits of the main parameters in the method and the relations based on the limits", "determination of the allowed limits of important variables and their situation as well as other involving variables and then comparison with the results of the physical structure of the method" in two areas of "theory or theory and practice" and "real and practical". In this way, the process of form finding is done.The characteristics of the resulted optimal shape using the numerical methods are such as having the maximum rigidity or minimum bending, membrane behavior, the minimum energy, complexity and diversity shapes, and etc. Although computational methods are more accurate but the most characters of optimal computational form are the same as physical method and some characters such as minimal total energy and optimistic displacement are added. Forms may also have such characteristics and the methods acquire new characteristics of the forms could be existed. Most of the results achieved using various methods are the same. All methods are reliable for application except methods no. 3 and 1 and half of method no. 5.

کلیدواژه‌ها [English]

  • Form Finding
  • Shell Structures
  • Hanging Model
  • Computational Methods

-- Allen, E., Zalewski, W. (2009). Form and Forces: Designing Efficient, Expressive Structures. John Wiley and sons.

-- Asmaljee, Z. (2013). Form- Finding of Thin Structures. Johannesburg: University of the Witwatersrand.

-- Bellés, P., Ortega, N., Rosales, M., Andrés, O. (2009). Shell Form-Finding: Physical and Numerical Design Tools.

Engineering Structures. 31(11), 2656-66.

-- Bletzinger, K-U., Ramm, E. (2001). Structural Optimization and Form Finding of Light Weight Structures. Computers

& Structures., 79(22-25), 2053-62.

-- Bletzinger, K-U., Wüchner, R., Daoud, F., Camprubi, N. (2005). Computational Methods for Form Finding and

Optimization of Shells and Membranes. Computer Methods in Applied Mechanics and Engineering. 194 (30-33),

3438-52.

-- Brew, J.S., Lewis, W.J. (2007). Free Hanging Membrane Model for Shell Structures. International Journal for

Numerical Methods in Engineering. 71,1513-33.

-- Chilton, J. (2000). The Engineer’s Contribution to Contemporary Architecture: Heinz Isler, London: Thomas Telford

Press, http://books. Google.com

-- __________. (2010).Heinz Isler’s Infinite Spectrum Form-Finding in Design. Architectural Design. (4), 64-71.

-- Draper, P. (2008). Building for the Future. Ph.D. Thesis, Princeton University.

-- Eٍngle, H.(n.d.). Structure Systems. (Corporation of Fine-Arts Faculty of Tehran University, Trans.)

-- Huerta, S. (2006). Structural Design in the Work of Gaudi, Architectural Science Review. 49(4), 324-39.

-- Kilian, A., Ochsendorf, J. (2005). Particle-Spring Systems for Structural form Finding. Proceedings of the International

Association for Shell and Spatial Structures (IASS), 46 (147).

-- Lewis, W. (2005). Understanding Novel Structures through Form-Finding. Proceedings of ICE, 178-85.

-- Linkwitz, K. (1999). About form Finding of Double-Curved Structures. Engineering Structures. 21,709-18.

-- Galant, L, Antonio, J. (2009). Cylindrical Thin Concrete Shells, MS thesis, Stockholm, Sweden: KTH Architecture

and the Built Environment.

-- Mainstone, R.J. (2001). Development in Structural Form. Cambridge, Massachusetts: The MIT Press.

-- Maurin, B., Motro, R. (2004). Concrete Shells Form-Finding with Surface Stress Density Method. Structural

Engineering. 130(6), 961-8.

-- Moore, F. (1385). Understanding Structures, (M. Golabchi, trans.)(4th ed.). Tehran: University of Tehran Press.

-- Pavlik, B. (2006). Shape and Strength: Load Bearing Digital Geometries. Boston Society of Architects Design

Research Grants.

-- Ramm E., Mehlhorn G. (1991). On Shape Finding Methods and Ultimate Load Analyses of Reinforced Concrete

Shells, Engineering Structures. 13, 178-198.

-- Ramm E., Wall W.A. (2004). Shell Structures. International Journal for Numerical Methods in Engineering.

60(1), 381-427.

-- Salvadori, A. (1385). Structure in Architecture, (M. Golabchi, trans.)(6th ed.). Tehran: Tehran University Publications.

-- Shell structure, In Encyclopedia online Britannica. (2011). http://www.britannica.Com/Ebchecked/topic/ 1385998/

shell-structure

-- Shells and Folded Plate Members. In ACI. 318 Building Code and Commentary. (Ch. 19).

-- Adriaenssens, S., Block, P., Veenendaal, D., Williams, C. (EDs). (2014). Shell Structures for Architecture, form

Finding and Optimization, Routledge.

-- Tomas, A., Morti, P. (2010). Shape and Size Optimization of Concrete Shells, Engineering Structures. 32, 1650-

1658.

-- Trovalusci, P., Tinelli, A. (2010). Structural Optimization Vs. Shape Design. International Symposium on the Tectonics

in Architecture: between Aesthetics and Ethics, ICSA.

-- Vizotto, I. (2010). Computational Generation of Free-Form Shells in Architectural Design and Civil Engineering.

Automation in Construction. 19(8), 1087-1105.