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doi:10.3850/978-981-08-9247-0_rp083-icsas11
Pre-Stressed Stayed Steel Columns Non-Linear Dynamic Assessment
R. R. De Araujo1, P. C. G. Da S. Vellasco2, J. G. S. Da Silva2, L. R. O. De Lima2, S. A. L. De Andrade3 and L. A. P. S. Da Silva4
1Engineering Department, Federal Center for Technological Education Celso Suckow da Fonseca - CEFET-RJ
2Structural Engineering Department, State University of Rio de Janeiro - UERJ, Brazil
3Civil Engineering Department, Pontifical Catholic University of Rio de Janeiro - PUC-Rio, Brazil
4Institute for Sustainability and Innovation in Structural Engineering - ISISE, Civil Engineering Department, University of Coimbra, Portugal
ABSTRACT
Prestressed stayed steel columns represent an ingenious solution for supporting structures like large span tensile fabric structures, slender temporary shoring systems among others. Various geometrical and material parameters proved to be significant in determining the load capacity of these particular types of stayed columns like: column height, diameter, thickness, etc. Since these structural systems are made of very slender columns they became substantially lighter than conventional temporary shoring systems like scaffolds. Although these structures dates back from the 1960's their structural behaviour are still not fully understood, especially when subjected to dynamic actions [1-7]. These aspects motivated a comprehensive study of the structural system dynamic response when submitted to impact loads [8]. A particular case of these structural systems is composed of a slender central column, four cross bars perpendicularly positioned in relation to the central column main axis and four steel cables (or steel bars). The investigated pre-stressed column system adopted tubular sections for the main column and four perpendiculars braces with the following dimensions: main column length equal to 12m; main column external diameter equal to 89.3mm; main column thickness equal to 3.2mm; braces length equal to 600mm; braces external diameter equal to 42.6mm and braces thickness equal to 3.0mm. Cables were used as stays, with a 6.35mm diameter. The load bearing capacity of the stayed system was substantially increased by the additional restriction provided by the tie forces that are transferred to the main columns by means of horizontal tubes, perpendicularly welded to the column midpoint [1-7]. A finite element computational model was developed and implemented in the ANSYS program. The main tubular column and secondary cross bars were modelled by PIPE20 elements while the ties were used LINK10 elements. First the pre-stressed column dynamic response was investigated through an analysis of its natural frequencies and vibration modes and was followed by a non-linear time-domain analysis. This paper presents the results related to the case where the top of the pre-stressed system was submitted to various levels of dynamic actions to simulate sudden impacts.
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