Post-punching behaviour of flat slabs strengthened with a new technique using post-tensioning

Published on Jul 1, 2012in Engineering Structures3.548
· DOI :10.1016/J.ENGSTRUCT.2012.03.014
Duarte M. V. Faria10
Estimated H-index: 10
(NOVA: Universidade Nova de Lisboa),
Valter José da Guia Lúcio10
Estimated H-index: 10
(NOVA: Universidade Nova de Lisboa),
A. Pinho Ramos7
Estimated H-index: 7
(NOVA: Universidade Nova de Lisboa)
Sources
Abstract
Abstract This work presents an experimental study concerning the post-punching behaviour of flat slabs strengthened with a new technique based on post-tensioning with anchorages by bonding using an epoxy adhesive. This strengthening technique proved efficient with respect to ultimate and serviceability states. Five slab specimens were tested in the post-punching range and it was found that the post-punching resistance was on average 78% of the punching resistance. This paper reports the development of strand forces and slab displacements from the beginning of the tests, including the bond stresses developed at several stages of the loading process. It was observed that top reinforcement bars were capable of transmitting post-punching loads to the prestressing strands. Taking this into account and based on the load bath envisaged from the column to the slab, expressions for the vertical load capacities corresponding to the parts of the load path are presented and compared with the experimental results, showing their ability to predict both ultimate loads and modes of failure. Compared with other strengthening techniques, the one proposed here not only upgrades ultimate and serviceability behaviour but also adds post-punching resistance, which is a great advantage in the event of progressive collapse, since it may avoid the collapse of an entire structure, thus reducing the risk of material and human losses.
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This work aims to study a new flat slab strengthening technique based on post-tensioning with anchorages by bonding using an epoxy adhesive. The main advantages of this technique over the traditional prestress strengthening systems that use mechanical anchorages are that it does not need external permanent anchorages, meaning that the forces are introduced into the concrete gradually instead of being localized, thereby preserving aesthetics and useable space. The seven tested slab models show th...
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