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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, (2019) 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.

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 , Revista Portuguesa de Engenharia de Estruturas, Volume Série III, Issue 9, p.67-74, (2019)
Behaviour of reinforced-concrete flat slabs with stirrups under reversed horizontal cyclic loading, Almeida, André F. O., Alcobia Bruno, Ornelas Miguel, Marreiros Rui, and Ramos António Pinho , Magazine of Concrete Research, Volume 72, Number 7, p.339-356, (2020) AbstractWebsite

This paper describes the experimental campaign to study the behaviour of reinforced-concrete flat slab structures with steel stirrups as punching shear reinforcement, under combined vertical and horizontal cyclic loading. The vertical load was first applied and kept constant during the test, while, regarding the cyclic horizontal loading, imposed cyclic drifts were increased until failure. Four slab specimens with shear reinforcement were tested and the results compared to a control slab specimen without shear reinforcement. The studied variables were different shear reinforcement ratios and the number of stirrup layers. The slabs were 4·15 × 1·85 m2 and 0·15 m thick, connected to two steel half-columns. The test setup used was developed by the research team and aimed to simulate the boundary conditions of a flat slab, representing the slab between middle spans in one direction and between zero bending moment points in the other direction. Results show that the use of steel stirrups as shear reinforcement is very effective, increasing shear, drift and energy dissipation capacities. The obtained results were also compared to the provisions given by European and American codes.

Punching behaviour of RC flat slabs under reversed horizontal cyclic loading, Almeida, André F. O., Inácio Micael M. G., Lúcio Válter J. G., and Ramos António Pinho , Engineering Structures, Volume 117, p.204–219, (2016) AbstractWebsite

The aim of this work is to study the behaviour of reinforced concrete flat slab structures under combined vertical and horizontal cyclic loading. A total of five specimens were cast and tested: a control specimen was punched without eccentricity, one specimen was tested under constant vertical loading and monotonically increased eccentricity until failure and the remaining three were tested under constant vertical load, at different shear ratios, and cyclic horizontal loading with increasing horizontal drift ratios. All slabs were similar, measuring 4.25×1.85×0.15m3. The reinforced concrete slab specimens were connected to two steel half columns by 0.25×0.25m2 rigid steel plates, prestressed against the slab using steel bolts, to ensure monolithic behaviour. The cyclic tests were performed using an innovative test setup that allows bending moment redistribution, line of inflection mobility, assures equal vertical displacements at the North-South borders and symmetrical shear forces. Results show that cyclic horizontal actions are very harmful to the slab–column connection, resulting in low horizontal drifts and energy dissipation.

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 n/a, Number n/a, (2019) 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.

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.

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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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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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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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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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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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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D
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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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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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.

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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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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