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F
Reabilitação Sustentável de Estruturas –Reforço de Lajes de Edifícios de Betão Armado, Faria, Duarte, Lúcio Válter, and Ramos António Pinho , CRSEEL – 2ª Conferência Construção e Reabilitação Sustentável de Edifícios no Espaço Lusófono, Lisbon, (2012) Abstract

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Post-punching behaviour of flat slabs strengthened with a new technique using post-tensioning, Faria, Duarte M. V., Lúcio Válter J. G., and Pinho Ramos A. , Engineering Structures, jul, Volume 40, p.383–397, (2012) AbstractWebsite

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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Estudo Teórico-Experimental da Resistência ao Punçoamento de Lajes Fungiformes de Betão Aramado com Pilar de Canto Reentrante sem Armadura de Punçoamento, e Elaine Albuquerque, Guilherme Melo, António Ramos Válter Lúcio , 5ªs Jornadas Portuguesas de Engenharia de Estruturas, Encontro Nacional de Betão Estrutural 2014, 9º Congresso Nacional de Sismologia e Engenharia Sísmica, Lisbon, (2014) Abstract

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On the distribution of shear forces in non-axisymmetric slab-column connections, Einpaul, J., Vollum R. L., and Ramos A. P. , High Tech Concrete: Where Technology and Engineering Meet - Proceedings of the 2017 fib Symposium, p.841-848, (2017) Abstract
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Punching shear behavior of edge column connections in continuous flat slabs, Einpaul, Jürgen, Vollum Robert, and Ramos António , Proceedings of the 39th IABSE Symposium – Engineering the Future, Vancouver, Canada, (2017)
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Development of a Design Proposal for a Slab Strengthening System using Prestress with Anchorages by Bonding, Duarte Faria, Válter Lúcio, and Ramos António , fib symposium Tel Aviv 2013, Tel Aviv, p.281–284, (2013) Abstract

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Punching of Strengthened Concrete Flat Slabs—Experimental Analysis and Comparison with Codes, Duarte, Faria, Micael Inácio, Válter Lúcio, and António Ramos , Structural Engineering International, may, Volume 22, Number 2, p.202–214, (2012) AbstractWebsite

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Strengthening of flat slabs with transverse reinforcement, Duarte, Inácio, Ramos António M. P., and Lúcio Válter J. G. , Proceedings of CCC, Porto, (2008) Abstract

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On the efficiency of flat slabs strengthening against punching using externally bonded fibre reinforced polymers, Duarte, Duarte M., Einpaul Jurgen, Ramos António M., {Fernandez Ruiz} Miguel, and Muttoni Aurelio , Construction and Building Materials, Volume 73, p.366–377, (2014) Abstract

One possibility for strengthening existing flat slabs consists on gluing fibre reinforced polymers (FRPs) at the concrete surface. When applied on top of slab-column connections, this technique allows increasing the flexural stiffness and strength of the slab as well as its punching strength. Nevertheless, the higher punching strength is associated to a reduction on the deformation capacity of the slab-column connection, which can be detrimental for the overall behaviour of the structure (leading to a more brittle behaviour of the system). Design approaches for this strengthening technique are usually based on empirical formulas calibrated on the basis of the tests performed on isolated test specimens. However, some significant topics as the reduction on the deformation capacity or the influence of the whole slab (accounting for the reinforcement at mid-span) on the efficiency of the strengthening are neglected. In this paper, a critical review of this technique for strengthening against punching shear is investigated on the basis of the physical model proposed by the Critical Shear Crack Theory (CSCT). This approach allows taking into account the amount, layout and mechanical behaviour of the bonded FRP's in a consistent manner to estimate the punching strength and deformation capacity of strengthened slabs. The approach is first used to predict the punching strength of available test data, showing a good agreement. Then, it is applied in order to investigate strengthened continuous slabs, considering moment redistribution after concrete cracking and reinforcement yielding. This latter study provides valuable information regarding the differences between the behaviour of isolated test specimens and real strengthened flat slabs. The results show that empirical formulas calibrated on isolated specimens may overestimate the actual performance of FRP's strengthening. Finally, taking advantage of the physical model of the CSCT, the effect of the construction sequence on the punching shear strength is also evaluated, revealing the role of this issue which is also neglected in most empirical approaches.

Nonlinear analysis of flat slab-column connections to optimize the use of HPFRC under monotonic vertical loading, Díaz, Rafael Sanabria, Isufi Brisid, Trautwein Leandro Mouta, and Ramos António Pinho , Structural Concrete, Volume 24, Number 5, p.5787 – 5807, (2023) AbstractWebsite
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Nonlinear analysis of flat slab-column connections to optimize the use of HPFRC under monotonic vertical loading, Díaz, Rafael Sanabria, Isufi Brisid, Trautwein Leandro Mouta, and Ramos António Pinho , Structural Concrete, (2022) AbstractWebsite
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Testing of a full-scale flat slab building for gravity and lateral loads, Coronelli, Dario, Lamperti Tornaghi Marco, Martinelli Luca, Molina Francisco-Javier, Muttoni Aurelio, Pascu Ion Radu, Pegon Pierre, Peroni Marco, Ramos António Pinho, Tsionis Georgios, and Netti Teresa , Engineering Structures, Volume 243, (2021) AbstractWebsite
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A state of the art of flat-slab frame tests for gravity and lateral loading, Coronelli, Dario, Muttoni Aurelio, Pascu Ion R., Ramos Antonio P., and Netti Teresa , Structural Concrete, Volume n/a, Number n/a, (2020) AbstractWebsite

Abstract This paper presents a critical review of the state of the art of experimental research concerning the seismic response of reinforced concrete flat slab frames. After a summary of tests on connections, the paper examines tests carried out on frames with gravity and cyclic lateral loading, and shake table tests; scaled specimens and one real scale study are included. A discussion of the results reached so far is provided focusing on the global response, the different load types and effects; the ultimate rotations at failure in relation to the gravity shear and a classification of different failure modes for different types of connections. Based on this analysis, the research needs are highlighted. An experimental program launched to address these open questions is described. Further open topics are highlighted.

Flat Plate Building and Frame Full Scale Tests for European Design Provisions, Coronelli, Dario, Muttoni Aurelio, Pascu Radu, and Ramos Antonio , American Concrete Institute, ACI Special Publication, Volume SP-353, p.73 – 96, (2022) Abstract
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Flat slab structural response for seismic european design. Full scale testing results, Coronelli, Dario, Martinelli Luca, Muttoni Aurelio, Pascu Radu, and Ramos Antonio , fib Symposium, Volume 2021-June, p.1831 – 1839, (2021) Abstract
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Flat slab structural response for seismic european design. Full scale testing results, Coronelli, Dario, Martinelli Luca, Muttoni Aurelio, Pascu Radu, and Ramos Antonio , fib Symposium, Volume 2021-June, p.1831 – 1839, (2021) Abstract
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Influence of prestressing on the punching strength of post-tensioned slabs, Clement, Thibault, Ramos Antonio Pinho, Ruiz Miguel Fernandez, and Muttoni Aurelio , Engineering Structures, Volume 72, p.56–69, (2014) Abstract

Previous researches on punching of post-tensioned slabs have shown a number of phenomena significantly influencing their strength and behaviour. However, no general agreement is yet found on a physical theory (either in codes of practice or in design models) suitably describing the influence of prestressing and how should it be accounted on the punching shear behaviour. In this paper, the authors present the results of tests on 15 slabs (3000. ??. 3000. ??. 250. mm) tested to failure under different loading conditions. The aim of the tests was to investigate in a separate manner the different actions induced by prestressing on the punching shear strength (in-plane forces, bending moments and bonded tendons). These results are finally investigated on the basis of the physical model of the Critical Shear Crack Theory. The fundamentals of this theory are presented and adapted to post-tensioned slabs, providing a rational explanation of the observed phenomena and measured strengths. ?? 2014 Elsevier Ltd.

Design for punching of prestressed concrete slabs, Clement, Thibault, Ramos Antonio Pinho, Ruiz Miguel Fernandez, and Muttoni Aurelio , Structural Concrete, Volume 14, Number 2, p.157–167, (2013) Abstract

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Applied element method simulation of experimental failure modes in RC shear walls, Cismasiu, Corneliu, Ramos António Pinho, Moldovan Ionut D., Ferreira Diogo F., and Filho Jorge B. , Computers and Concrete, Volume 19, Issue 4, p.365–374, (2017) Abstract

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B
Seismic Performance of Reinforced Concrete Buildings with Joist and Wide-Beam Floors during the 26 November 2019 Albania Earthquake, Baballëku, Markel, Isufi Brisid, and Ramos António Pinho , Buildings, Volume 13, Number 5, (2023) AbstractWebsite
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A
Flat Slab Punching Behaviour under Cyclic Horizontal Loading, André Almeida, Micael Inácio, Válter Lúcio, and Ramos António , fib symposium Copenhagen 2015, Concrete – Innovation and Design, Copenhagen, (2015) Abstract

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Punçoamento em Lajes Fungiformes Sujeitas a Ações Cíclicas horizontais – Estudo Experimental, e André Almeida, Micael Inácio}, Válter Lúcio António Ramos , 5ªs Jornadas Portuguesas de Engenharia de Estruturas, Encontro Nacional de Betão Estrutural 2014, 9º Congresso Nacional de Sismologia e Engenharia Sísmica, Lisbon, (2014) Abstract

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Resposta da ligação pilar-laje fungiforme sujeitas a ações horizontais cíclicas reforçadas com estribos, Almeida, André, Ramos António, Marreiros Rui, Lúcio Válter, and Faria Ricardo , Encontro Nacional Betão Estrutural 2018, 7-9 Nov., LNEC, Lisboa, (2018)
Flat Slabs under Cyclic Reversed Horizontal Loads, Almeida, André, Lúcio Válter, and Ramos António , 3rd NOVA-Yamaguchi International Seminar – Earthquake Resistant Structures, Caparica, (2016)
Behavior of RC flat slabs with shear bolts under reversed horizontal cyclic loading, Almeida, André F. O., Ramos António P., Lúcio Válter, and Marreiros Rui , Structural Concrete, Volume 21, Number 2, p.501-516, (2020) AbstractWebsite

Abstract An experimental work on reinforced concrete flat slab specimens to test the efficiency of postinstalled bolts, as punching shear reinforcement in resisting vertical and cyclic horizontal loads, was conducted and is presented in this paper. The test protocol consisted in increasing horizontal drifts combined with constant vertical load until failure. Two different detailing solutions for the shear reinforcement were considered, one using a radial distribution around the column and another using a cross distribution, being the results compared with a previously tested reference specimen. The dimensions of the specimens were 4.25 x 1.85 x 0.15 m3. The test setup used for these tests was developed by the research team and simulates the boundary conditions with already recognized good results. Postinstalled steel bolts were proven to be an efficient solution for strengthening of existing structures, improving the structural behavior, and the punching resistance.