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Keywords: three-dimensional volume modelling, hollow core floors, LUSAS, finite element analysis, load sharing, prestressed concrete.

Summary

Construction of modern structures is becoming increasingly efficient as a result of improved analysis and design. The development of hollow core (HC) floors is one example of such efficiency. They have become an important component in both domestic and commercial construction, with precast flooring accounting for approximately 50% of flooring systems worldwide [1]. The slabs are designed as individual units, simply supported and one way spanning. Completed floors consist of a number of these individual slabs placed alongside each other and then joined together using a concrete or mortar grout to create a floor membrane.

Previous finite element (FE) analysis of these floors has involved modelling the slabs as plate or shell elements and the joints as lines. A pre-eminent researcher in the area of HC research has stated that "To model every void explicitly would make the analysis too cumbersome" [2]. Whilst this was true in the past, developments in computing power and FE packages now make it possible to model and analyse full three-dimensional volumetric precast concrete HC floors with their exact material and geometric properties.

This paper presents a study of a three-dimensional solid volume FE analysis of HC floors using the structural analysis software LUSAS (version 14.5-2). The structural response of complete floors is not accurately determined by traditional hand analysis whereas a single slab is amenable to hand calculations. As a method of validation of the FE modelling a single slab 200mm x 1200mm x 11 core and of span 6m was modelled. Displacement, stress and reaction results recovered from the FE analysis were found to produce accurate results when compared to the hand calculations.

Following on from the single slab analysis a complete floor analysis was undertaken. Floors consisting of five 200mm x 1200mm x 11 core slabs of span 4m, 6m and 8m were modelled. The results from the floor analysis were compared with graphs of load distribution factors, which are included in BS EN 1168:2005 [3] and in the Fédération Internationale de la Précontrainte (FIP) recommendations (1988) [4]. The results indicate that more economical designs could be achieved by the use of FE analysis.

References

1: K.S. Elliott, "Precast concrete structures", Butterworth-Heinemann, Oxford, United Kingdom, 2002.
2: J.F. Stanton, "Response of Hollow-Core Slab Floors to Concentrated Loads", PCI Journal, 37(4), 98-113, 1992.
3: Bristish Standards Institution, "BS EN 1168:2005, Precast concrete products-Hollow core slabs", London, United Kingdom, 2005.
4: Fédération Internationale de la Précontrainte, "Precast prestressed hollow core floors", Thomas Telford, London, United Kingdom, 1988.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 96 PROCEEDINGS OF THE THIRTEENTH INTERNATIONAL CONFERENCE ON CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING COMPUTING Edited by: B.H.V. Topping and Y. Tsompanakis Paper 167 Three-Dimensional Solid Finite Element Modelling and Analysis of Precast Hollow Core Floors D.F. Hodge¹, B.D. O'Rourke¹, J.J. Murphy¹ and J.R. Harrington² ¹Department of Civil Structural and Environmental Engineering, ²School of Building and Civil Engineering Cork Institute of Technology, Ireland doi:10.4203/ccp.96.167 purchase the full-text of this paper Full Bibliographic Reference for this paper D.F. Hodge, B.D. O'Rourke, J.J. Murphy, J.R. Harrington, "Three-Dimensional Solid Finite Element Modelling and Analysis of Precast Hollow Core Floors", in B.H.V. Topping, Y. Tsompanakis, (Editors), "Proceedings of the Thirteenth International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 167, 2011. doi:10.4203/ccp.96.167 Keywords: three-dimensional volume modelling, hollow core floors, LUSAS, finite element analysis, load sharing, prestressed concrete. Summary Construction of modern structures is becoming increasingly efficient as a result of improved analysis and design. The development of hollow core (HC) floors is one example of such efficiency. They have become an important component in both domestic and commercial construction, with precast flooring accounting for approximately 50% of flooring systems worldwide [1]. The slabs are designed as individual units, simply supported and one way spanning. Completed floors consist of a number of these individual slabs placed alongside each other and then joined together using a concrete or mortar grout to create a floor membrane. Previous finite element (FE) analysis of these floors has involved modelling the slabs as plate or shell elements and the joints as lines. A pre-eminent researcher in the area of HC research has stated that "To model every void explicitly would make the analysis too cumbersome" [2]. Whilst this was true in the past, developments in computing power and FE packages now make it possible to model and analyse full three-dimensional volumetric precast concrete HC floors with their exact material and geometric properties. This paper presents a study of a three-dimensional solid volume FE analysis of HC floors using the structural analysis software LUSAS (version 14.5-2). The structural response of complete floors is not accurately determined by traditional hand analysis whereas a single slab is amenable to hand calculations. As a method of validation of the FE modelling a single slab 200mm x 1200mm x 11 core and of span 6m was modelled. Displacement, stress and reaction results recovered from the FE analysis were found to produce accurate results when compared to the hand calculations. Following on from the single slab analysis a complete floor analysis was undertaken. Floors consisting of five 200mm x 1200mm x 11 core slabs of span 4m, 6m and 8m were modelled. The results from the floor analysis were compared with graphs of load distribution factors, which are included in BS EN 1168:2005 [3] and in the Fédération Internationale de la Précontrainte (FIP) recommendations (1988) [4]. The results indicate that more economical designs could be achieved by the use of FE analysis. References 1 K.S. Elliott, "Precast concrete structures", Butterworth-Heinemann, Oxford, United Kingdom, 2002. 2 J.F. Stanton, "Response of Hollow-Core Slab Floors to Concentrated Loads", PCI Journal, 37(4), 98-113, 1992. 3 Bristish Standards Institution, "BS EN 1168:2005, Precast concrete products-Hollow core slabs", London, United Kingdom, 2005. 4 Fédération Internationale de la Précontrainte, "Precast prestressed hollow core floors", Thomas Telford, London, United Kingdom, 1988. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £130 +P&P)
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