On the investigation of providing space truss roofs with ductility until failure under monotonically increasing vertical loads

Yıl 2020, Cilt: 26 Sayı: 3, 432 - 439, 08.06.2020

Cüneyt Vatansever Haluk Emre Alçiçek

Öz

The aim of this paper is to investigate the nonlinear behavior of space truss roofs subject to different load accumulation forms considering the effect of initial imperfection and slenderness ratio of the truss members. For this, a typical space truss roof using MERO-connection type with flat double-layer was selected as a sample. 3D model of the roof was developed and analyzed by using OpenSEES. Nonlinear behavior of each typical bar of the space truss roof, which, was mainly composed of particular sub-elements such as a tubular element, bolts, sleeves and spheres was represented by a single truss bar. Axial load-displacement relationship of each single truss bar was obtained from nonlinear analysis performed under reversal cyclic loading. Besides, three different types of load distribution that simulates accumulation of rainwater or drifted snow were taken into account as an external load acting on upper layer of the roof system. Analyses results showed that load carrying capacity of the space truss roofs was susceptible to the form of accumulation and reduces abnormally when the accumulation, in particular, occurred locally. Furthermore, failure mode of the system designed with optimal solution was dominated by buckled truss bars and brittle failure occurred. Also initial imperfection had a negative effect on the members in compression.

Anahtar Kelimeler

Space truss roof, MERO-connection, Initial imperfection, load accumulation

Uzay kafes çatı sistemlerinin artan düşey yükler altında sünekliğinin araştırılması

Öz

Bu çalışmada uzay kafes çatı sistemlerinin çeşitli yük birikme senaryoları altındaki doğrusal olmayan davranışı, çubuk eleman başlangıç kusurları ve çubuk eleman narinlikleri de dikkate alınarak incelenmiştir. MERO düğüm noktasına sahip iki adet örnek uzay kafes çatı sistemi OpenSEES yazılımı üç boyutlu olarak modellenerek analizler gerçekleştirilmiştir. Bulonlar, somunlar ve düğüm noktası kürelerinden oluşan her bir çubuk elemanın davranışı tekil çubuklar üzerinde tanımlanarak genel sisteme aktarılmıştır. Her bir çubuk elemanın eksenel yük-yerdeğiştirme davranışları çevrimsel tekrarlı yükler altında analizler gerçekleştirilerek elde edilmiştir. Genel sistem analizleri çatının tamamında, yarısında ve dörtte birinde yağmur suyu veya kar yükü yığılmalarını yansıtacak şekilde belirlenen yükleme altında gerçekleştirilmiştir. Analizler sonucunda uzay kafes çatı sistemlerinin yük yığılmalarına karşı hassas oldukları ve lokal bölgelerde oluşan yük yığılmalarının sistemin taşıma kapasitesini düşürdüğü görülmüştür. Bunun yanında, en ekonomik kesitlerle boyutlandırılan sistemde göçme basınç çubuklarının burkulması ile gevrek bir şekilde meydana gelmiştir. Ayrıca, çalışma kapsamında başlangıç kusurlarının çubuk elemanların basınç kapasitelerini düşürdüğü görülmüştür.

Anahtar Kelimeler

Uzay kafes çatı sistemleri MERO düğüm noktası, Başlangıç kusuru, Yük yığılması

Kaynakça

• Shahrabadi H. “The study of different geometrical parameter effects for single grid layers of space structure on performance level for vertical load of earthquake”. American Journal of Civil Engineering, 3(2-2), 10-17, 2015.
• Augenti N, Parisi, F. “Buckling analysis of a long-span roof structure collapsed during construction”. Journal of Performance of Constructed Facilities, 27(1), 77-88, 2011.
• Biegus A, Rykaluk, K. “Collapse of katowice fair fuilding”. Engineering Failure Analysis, 16(5), 1643-1654, 2009.
• Piroglu F, Ozakgul K, Iskender H at al. “Site investigation of damages occurred in a steel space truss roof structure due to ponding”. Engineering Failure Analysis, 36, 301-313, 2014.
• Piroglu F, Ozakgul K. “Partial collapses experienced for a steel space truss roof structure induced by ice ponds”. Engineering Failure Analysis, 60, 155-165, 2016.
• Rosen A, Schmit LA. “Design-oriented analysis of imperfect truss structures-Part I”. International Journal for Numerical Methods in Engineering, 14, 1309-1321, 1979.
• El-Sheikh A. “Effect of member length imperfections on triple-layer space trusses”. Engineering Structures, 19(7), 540-550, 1997.
• Zhou Z, Meng S, Wu J. “Stability analysis of prestressed space truss structures based on the imperfect truss element”. International Journal of Steel Structures, 9(3), 253-260, 2009.
• Uriz P, Filippou FC, Mahin SA. “Model for cyclic inelastic buckling of steel braces”. Journal of Structural Engineering, 134(4), 619-628, 2008.
• Lee PS, Noh HC. “Inelastic buckling behavior of steel members under reversed cyclic loading”. Engineering Structures, 32(9), 2579-2595, 2010.
• OpenSEES. “Open System for Earthquake Engineering Simulation”. https://opensees.berkeley.edu/ (10.07.2018).
• Lan TT. Space Frame Structures. Editors: Chen WF, Lui EM. Handbook of Structural Engineering, 24.1-24.50, Boca Raton, FL, USA, CRC Press, 2005.
• SAP2000 “Integrated Structural Analysis and Design”. https://www.csiamerica.com/products/sap2000 (10.07.2018).
• Collins IM. Collapse Analysis of Double-Layer Grids. PhD. Thesis, University of Surrey, Surrey, UK, 1981.
• Hamid YS, Disney P, Parke GAR. “Progressive collapse of double-layer space trusses”. ABSE-IASS Symposium, London, UK, 20-23 September, 2009.
• Caglayan O, Yuksel E. “Experimental and finite element investigations on the collapse of a Mero space truss roof structure-A case study”. Engineering Failure Analysis, 15(5), 458-470, 2008.
• Grigorian M. “Performance control for efficient design of double-layer grids under uniform loading, International”. Journal of Advanced Structural Engineering, 6(1), 52, 2014.
• Mazzoni S, McKenna F, Scott MH, et al. “OpenSees command language manual”. https://opensees.berkeley.edu/OpenSees/manuals/usermanual/OpenSeesCommandLanguageManualJune2006.pdf (10.07.2018).
• Applied Technology Council. “Guidelines for Cyclic Seismic Testing of Components of Steel Structures”. California, USA, 24, 1992.
• Federal Emergency Management Agency. “Prestandard and Commentary for the Seismic Rehabilitation of Buildings”. Washington DC, USA, 356, 2000.
• American Institute of Steel Construction. “Specification for Structural Steel Buildings”. Illinois, USA, 360, 2016.