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Joaquim A.O. Barros

Joaquim A.O. Barros
University of Minho · Institute for Sustainability and Innovation in Structural Engineering (ISISE)

PhD

About

574
Publications
136,013
Reads
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9,339
Citations
Citations since 2017
130 Research Items
5467 Citations
201720182019202020212022202302004006008001,000
201720182019202020212022202302004006008001,000
201720182019202020212022202302004006008001,000
201720182019202020212022202302004006008001,000
Additional affiliations
October 1988 - February 2014
University of Minho
Position
  • Professor (Full)

Publications

Publications (574)
Article
This paper is dedicated to the development of a new analysis-oriented model to simulate the axial and dilation behavior of FRP confined heat-damaged concrete columns under axial compressive loading. The model’s calibration has considered the experimental results from concrete circular/square cross-section specimens submitted to a certain level of h...
Article
This article describes the second blind simulation competition (BSC) organized by the fib WG 2.4.1, which aims to assess the predictive performance of models based on the finite element method (FEM) for the analysis and design of fiber reinforced concrete (FRC) structures. Slabs supported on columns or piles have becoming competitive applications f...
Chapter
The present work describes the analysis of a long and jointless concrete foundation reinforced with conventional steel meshes and discrete polypropylene fibers. A thermo-mechanical nonlinear transient simulation is performed to assess the cracking risk and magnitude of the fiber reinforced concrete (FRC) due to the heat development generated from t...
Article
Although a variety of analytical modeling approaches have been developed to simulate the axial response of Fiber-Reinforced Polymer (FRP) confined concrete columns, little effort has been dedicated to the development of simple but robust predictive models for heat-damaged concrete columns with FRP confinement. This study aims to present a new unifi...
Article
Even though analysis-oriented models exist to simulate the axial and dilation behavior of reinforced concrete (RC) columns strengthened with fiber-reinforced-polymer (FRP) full confinement arrangements, a reliable model developed/calibrated for FRP partially imposed confinements is not yet available, identified as a research gap. Therefore, this pa...
Article
Strengthening and rehabilitation of underground tunnels are frequently an inseparable part of upgrading the railway network. Short fibres have been replacing pre-installed steel mesh with technical and economic advantages on the stabilization and securing of rock and soil systems in underground tunnels through the fibre reinforced shotcrete (FRS) t...
Article
Despite the many axial confinement models already proposed for the determination of the peak compressive strength of Fiber-Reinforced Polymer (FRP) confined concrete columns, they are, in general, applicable only to concrete columns of circular or square cross-section, with full or partial confinement arrangements. In this study, by proposing a cro...
Article
Although steel and concrete composite floors are generally constructed with hot‐rolled steel, there are several benefits of using cold‐formed steel (CFS) in these structures, such as lightness and less susceptibility to corrosion. The main disadvantage of using CFS in the steel beams is its connection to concrete, since the CFS members are thin and...
Article
Some reinforced concrete (RC) structures requiring strengthening intervention are subjected to cyclic loads during their lifetime. To evaluate the effect of this kind of loading on the behavior of flexurally strengthened RC slabs with prestressed near‐surface mounted (NSM) carbon fiber reinforced polymer (CFRP) laminates, an experimental program fo...
Article
This paper presents a new pre-fabricated lightweight slab system where the relatively high post-cracking tensile capacity of steel fibre reinforced concrete (SFRC) is combined with the high ductility and tensile strength of optimized shape profiles made by cold formed steel sheets for a synergetic result in terms of structural performance. The SFRC...
Article
Full-text available
La investigación experimental ha demostrado el extraordinario potencial de la adición de fibras cortas a los materiales cementiceos, ya que mejoran significativamente el comportamiento de estructuras de hormigón en los estados límite de servicio y último. Para la simulación del comportamiento no lineal del material en estructuras de hormigón reforz...
Article
Full-text available
Steel fibre-reinforced concrete (SFRC) is an emerging class of composite for construction. However, a reliable method to assess the flexural behaviour of SFRC structural member is in lack. An analytical technique is proposed for determining the moment-curvature response of concrete beams reinforced with steel fibres and longitudinal bars (R/SFRC me...
Article
Even though the usage of Fiber-reinforced polymer (FRP) full confinement arrangement is a more reliable and efficient strengthening technique than a partially confining strategy, it might not be cost-effective in real cases of strengthening. Experimental researches have demonstrated that the confinement strengthening strategy is more effective for...
Article
This paper presents an experimental study about the development of a sustainable and multifunctional composite sandwich panel for the rehabilitation of reinforced concrete (RC) buildings from the 1960s to the mid-1980s. For this purpose, the cyclic behaviour of representative RC frames was assessed by performing in-plane quasi-static cyclic tests o...
Chapter
Steel-fibre-reinforced concrete (SFRC) is a strain rate sensitive material and, therefore, its dynamic and static compressive behaviour can be significantly different. In the present study, the effect of loading rate on the compressive behaviour of SFRC with 1% hooked end steel fibres is experimentally investigated. During impact loading, an inerti...
Chapter
Conventional concrete material shows relatively low ductility and energy dissipation capacity under high strain rate tensile loads. The use of steel fibers into concrete can significantly improve the tensile behavior of concrete subjected to high strain rate loads by fibers bridging the concrete crack surfaces, resulting in a high impact resistance...
Chapter
The present study is dedicated to develop a new axial stress-strain model for FRP-based confinement strategies in case of FRP fully/partially confined circular concrete columns under axial compressive loading. For calculating axial stress versus axial strain curve, a new formulation as a function of concrete dilation response was suggested based on...
Chapter
An analytical model to predict the torsional moment capacity and the type of failure of thin walled tubular reinforced concrete elements strengthened with near surface mounted (NSM) carbon fiber reinforced polymer (CFRP) laminates is proposed. The model implements the thin walled space truss analogy, which forms the basis of current design codes, a...
Chapter
Near surface mounted (NSM) strengthening technique, using fiber reinforced polymer (FRP) composite materials, is one of the most promising solutions for dealing with the deterioration problems of current reinforced concrete (RC) structures. However, intense research is still ongoing to keep improving this technique in the cases where its applicatio...
Chapter
The present work has been developed in the scope of the research project ‘‘Easyfloor – Development of composite sandwich panels for building floor rehabilitation”. This project aims at developing a hybrid sandwich panel, constituting an alternative construction system to conventional floor solutions, mainly for buildings rehabilitation. The develop...
Chapter
Coastal areas are an apprized environment by society that will continue to expand rapidly. Traditional coastal protection structures are commonly deployed to protect coastal areas endangered by natural extreme weather events. However, due to their limited efficiency and very high costs, more efficient and sustainable strategies to deal with coastal...
Conference Paper
A exposição de estruturas de betão a temperaturas elevadas, como no caso de incêndio, conduz, entre outros, a uma degradação das propriedades mecânicas do material. Dependendo da temperatura e do tempo de exposição, esta ocorrência acidental potencia a ocorrência de fissuração e destacamento do betão – spalling (por vezes de forma explosiva), poden...
Article
The use of recycled materials and industrial by-products as sustainable constituents of cement-based materials could be an environmentally and technically promising solution for application to structural elements. In the present work, the technical and environmental impact of using recycled steel fibers as an alternative to industrial steel fibers...
Article
The present work assesses the potentialities of a new carbon fibre reinforced polymer (CFRP) bar, applied according to a hybrid technique for the flexural strengthening of cantilever type reinforced concrete (RC) structures, such as the case of RC balconies. The CFRP bar is formed by an inclined extremity that is inserted into a hole according to t...
Chapter
In this paper, a new approach is proposed for predicting reaction force in simply supported steel fiber reinforced concrete (SFRC) beams under impact loading (drop weight test) considering the energy conservation approach. If SFRC beams completely fail under impact load, it can be found that the total reaction force is equal to force capacity of SF...
Chapter
The superb performance of carbon fiber reinforced polymer (CFRP) composites as near surface mounted (NSM) reinforcement in strengthening solutions for structures is already well recognized. Due to their deficiencies in fire conditions, cement-based adhesives as an alternative to polymeric matrices are recently suggested as a solution in these syste...
Chapter
The present work describes an integrated approach that leads to the development of a new model capable of describing the tensile behavior (mode I) of fiber reinforced concrete (FRC), considering the orientation of the fibers, the fibers segregation along the cross-section of the FRC members and the pullout constitutive model of each fiber bridging...
Article
The strengthening intervention of RC structures often involves already cracked concrete. To evaluate the effect of the level of damage prior to the strengthening (pre-cracks) on the behavior of the flexurally strengthened RC slabs with prestressed NSM CFRP laminates, an experimental research was carried out. Two pre-cracking levels of damage were a...
Chapter
Experimental research has confirmed that the usage of fiber reinforced polymer (FRP) composite materials can be a reliable solution to substantially improve axial and dilation behavior of confined concrete columns. In this regard, FRP partial confinement system is a good compromise from the cost competitiveness point of the view, while the applicat...
Chapter
This paper presents the nonlinear finite element analysis of a new concept of offshore wind tower made by prefabricated prestressed fibre reinforced concrete (FRC) segments that are assembled to form the final structure. Fibre reinforcement aims to eliminate conventional passive steel reinforcement in order to avoid corrosion concerns and decrease...
Chapter
Off-shore wind towers are the wind farms used to harvest wind energy to generate electricity on water bodies. With the growing need of sustainable production for electricity, off shore wind towers are finding a rapid growth in application. In fact, 4% of European electricity demands will be generated by offshore wind towers by 2020 in European wate...
Chapter
In general, steel and concrete composite floors tend to present a reduced functional performance (considering thermal and acoustic conditions), due to their low mass and to the high conductivity of the steel elements. By including components with high thermal insulation capacity in these structural systems, it is possible to maintain the structure...
Article
In recent past, the authors developed an innovative modular system for low rise building made by structural sandwich panels. This system was conceived with the focus on the rationalization of the construction process and on the thermal efficiency of the building. Thus, the precast panels comprise two outer Steel Fibre Reinforced Self-Compacting Con...
Article
This paper presents a new technique based on dynamic X-ray radiography that can be used to assess fibre orientation during pouring of steel fibre reinforced cementitious composites. Synthetic examples were used to assess the suitability and robustness of the technique, which was shown to provide reliable measurements of fibre orientation even when...
Article
This study is dedicated to the development of a generalized confinement model applicable to circular concrete columns confined by FRP full and partial confinement arrangements. To simulate the axial stress versus strain curve, a new strength model is proposed addressing the relation of axial stress and confinement pressure during axial loading, who...
Article
Extreme wave value analysis under uncertainty scenarios was developed to estimate wave climate characteristics at 17 stations in southwestern European coast off the Iberian Peninsula. A comprehensive wave dataset downscaled with the Wave Watch III (WWIII) model by Meteogalicia under MarRisk Project was used considering results of models from the Co...
Article
Full-text available
The main purpose of the present work is to study the mechanical behavior and durability performance of recycled steel fiber reinforced concrete (RSFRC) under a chloride environment. To this end, the effect of chloride attack on the load-carrying capacity of pre-cracked RSFRC round panels is investigated by performing round panel tests supported on...
Article
This paper describes the development of a new inverse analysis approach to derive the fracture mode I parameters of fibre reinforced concrete (FRC) by using the experimental data obtained from three-point notched beam bending tests (3PNBBT) and round panel tests supported on three points (RPT-3PS). The approach is based on a global fitting strategy...
Article
This paper presents an experimental and numerical study aiming at the development of a sustainable and multifunctional composite sandwich panel for the rehabilitation of reinforced concrete (RC) buildings from the 1960s to the mid-1980s. The sandwich panel, which was designed for the structural, thermal and acoustic refurbishment of building facade...
Article
Numerical simulation of beams failing in shear is still a challenge. With the scope of verifying the applicability of smeared crack approaches to simulate the behavior of reinforced concrete (RC) beams failing in shear, a set of concrete beams reinforced with longitudinal glass fiber reinforced polymer (GFRP) bars, experimentally tested up to their...
Article
An experimental program was carried out for assessing the performance of a hybrid solution composed by CFRP systems for the simultaneous flexural and shear strengthening of RC beams. CFRP laminates, applied according to NSM technique, are used for the flexural strengthening, while U-shape CFRP discrete strips of wet lay-up sheet, applied according...
Article
Full-text available
The creation of new openings in masonry walls is a frequent intervention in existing buildings. Depending on their size and position, these interventions may cause a significant decrease of the wall's original in-plane strength and stiffness, thus compromising the building seismic resistance. Therefore, in masonry buildings, strengthening technique...
Chapter
In this study, compression, bending and shear properties of the dry fibre reinforced concrete (FRC) were experimentally characterized at its early age. Considering the application of the developed FRC in prefabricated prestressed beams, three-point notched beam bending tests were executed to analyse the post-cracking flexural behaviour, and direct...
Chapter
Concrete is a strain-rate sensitive material and shows relatively low ductility and energy dissipation capacity under high strain rate loads (HSRL) such as blast and impact, representative of terrorist attacks and accidents. Experimental research in the literature has evidenced that introducing steel fibers, into the concrete mixtures can significa...
Article
Nowadays, existing masonry buildings are frequently modified to satisfy living demands. These modifications may require the addition of new windows or doors in walls of structural functionality. In engineering practice, such modifications are generally designed and verified for vertical loads while, for seismic loads, the changes in the walls’ stru...
Book
This book gathers peer-reviewed contributions presented at the 3rd RILEM Spring Convention and Conference, held at Guimarães and hosted by the University of Minho, Portugal, on March 9-14, 2020. The theme of the Conference was “Ambitioning a Sustainable Future for Built Environment: comprehensive strategies for unprecedented challenges”, which was...
Article
Full-text available
The growing need for sustainable production of electricity highlights the importance and the necessity of having higher number and more effective offshore wind towers. The rapid growth of offshore wind towers is estimated to produce 4% of electricity demands in Europe by the end of 2020. The research described in this paper is part of a project ded...
Article
Experimental research has shown the extraordinary potential of the addition of short fibers to cement‐based materials by improving significantly the behavior of concrete structures for serviceability and ultimate limit states. Software based on the finite element method has been used for the simulation of the material nonlinear behavior of fiber‐re...
Article
Despite the key role of thin-walled tubular reinforced concrete (RC) members in major critical infrastructure projects, for example, bridges, their torsional performance is still not well understood and the effectiveness of strengthening systems cannot be easily assessed, especially when using innovative strengthening materials. With a large part o...
Article
In this study, a new hybrid technique for the strengthening of rectangular reinforced concrete (RC) columns under eccentric compressive loading is described, and its effectiveness is assessed experimentally. This technique combines two carbon fiber-reinforced polymer (CFRP) systems for complementary purposes: strips of CFRP wet layup sheets with a...
Article
In the present work, a multiscale model for fibre reinforced concrete (FRC) beams failing in bending is presented. At the microstructural level, the fibre is modelled as a one-dimensional continuum with axial, shear and bending deformability, with cohesive-like interfaces to simulate the interaction with the surrounding concrete. At the macroscopic...
Article
Full-text available
The addition of metallic fibres in concrete is a widely used technique to increase its resistance to crack opening, energy absorption capacity, and durability. The properties of the resulting composite strongly depend on the geometry of the fibres, which usually dispose of an hooked end, as well as on the mechanical properties of both the fibre and...
Article
Experimental research and real case applications are demonstrating that the use of fiber-reinforced polymer (FRP) composite materials can be a solution to substantially improve circular cross-section concrete columns in terms of strength, ductility, and energy dissipation. The present study is dedicated to developing a new model for estimating the...
Article
Nowadays, existing masonry buildings are frequently modified to satisfy living demands. These modifications may require the addition of new windows or doors in walls of structural functionality. In engineering practice, such modifications are generally designed and verified for vertical loads while, for seismic loads, the changes in the walls' stru...
Article
An experimental study on the performance of adhesive connection between Glass Fibre Reinforced Polymer (GFRP) plates and Steel Fibre reinforced self-compacting Concrete (FRC) was conducted. Fresh FRC was poured out onto the surface of GFPR plates, to create 40 square specimens (300 by 300 by 45 [mm]). Pull-off tests were performed to evaluate the t...
Article
Full-text available
This paper summarizes the results obtained in an experimental campaign on the effect of the displacement pullout rate and the inclination angle of the steel fiber pullout tests. For that purpose, specimens were obtained from a self-compacting concrete with a compressive strength of 86 MPa. In the experimental program, hooked-end steel fibers of 0.7...
Article
Full-text available
Based on a numerical model to simulate the static behaviour of a smooth fibre extracted from a cementitious matrix, a rate dependent friction law, widely used in earthquake engineering for steady-state slip phenomena, is proposed to capture the rate effect observed in dynamic pull-out tests for both smooth and hooked-end fibres. After calibrating t...
Article
Full-text available
A new formulation is herein proposed to embed discrete fibres and cracks in finite elements. The main features of the fibre behaviour are automatically accounted for, including bond and snubbing effects. Fibres can interact with cracks and are modelled without the need for additional degrees of freedom. A comprehensive constitutive law directly mod...
Article
This paper describes the development of a constitutive model for Fibre Reinforced Concrete (FRC) by combining the fibre and aggregate interlock resisting mechanisms. The proposed model predicts the normal and shear stresses in function of the crack opening and sliding displacements. For this purpose, two well established aggregate interlock models...
Conference Paper
Offshore wind towers are the wind farms used to harvest wind energy to generate electricity on water bodies. With the growing need of sustainable production for electricity, off shore wind towers are finding a rapid growth in application. In fact, 4% of European electricity demands will be generated by offshore wind towers by 2020 in European water...
Conference Paper
Experimental research has confirmed that the usage of fiber-reinforced polymer (FRP) composite materials can be a reliable solution to substantially improve axial and dilation behavior of confined concrete columns. In this regard, FRP partial confinement system is a good compromise from the cost competitiveness point of the view, while the applicat...
Article
Full-text available
Coastal areas accommodate a great part of large metropolises as they support a great amount of economic and leisure activities. The attraction of people to coastal zones is contributing to an intense and continuous urbanization of these areas, while the ecosystems are threatened by the increase of natural extreme weather events (e.g. intensity and...
Article
The efficacy of the NSM technique using prestressed CFRP laminates for the flexural strengthening of RC slabs was assessed experimentally. The results obtained indicated that the application of NSM CFRP laminates with a certain level of prestress is a suitable strategy to increase the load-carrying capacity of slabs in terms of service limit state...
Article
In this paper, a new model is developed based on the moment-rotation approach to predict average crack width and average crack spacing of flexural elements made of fibre reinforced concrete (FRC) that also include longitudinal steel and/or fibre reinforced polymer (FRP) bars. The post-cracking behaviour of FRC is simulated by a stress-crack width r...
Article
This paper presents a numerical modeling strategy based on the finite-element method (FEM) for the analysis of a temporary residential floor prototype composed of three jointed composite floor sandwich panels made of glass fiber–reinforced polymer (GFRP) skins, a polyurethane foam core (PU), and pultruded U-shaped GFRP profiles used as ribs. Panels...
Article
Full-text available
For structural elements exposed to chloride environments, an important aspect of Recycled Steel Fiber Reinforced Concrete (RSFRC) durability is the corrosion resistance. In the present work, an experimental program was carried out to evaluate the long-term effects of chloride attack on the post-cracking behavior of RSFRC by performing splitting ten...
Article
Full-text available
Fibre-reinforced polymer (FRP) is free from corrosion problem and is a viable alternative reinforcement material for concrete structures in lieu of steel reinforcing bars. Since FRP has lower elastic modulus compared to steel, the serviceability aspect of FRP reinforced concrete (FRP-RC) members should be particularly considered in the structural a...
Conference Paper
A new software, denominated FRCcalc, was developed for the analysis and design of fiber reinforced concrete (FRC) members based on the recommendations and design guidelines of MC2010. The software is guided for the analysis of FRC cross-sections with and without conventional steel reinforcements, submitted to bending and shear, in order to assess t...
Article
Full-text available
The BubbleDeck type slab (BD) is a reinforced concrete (RC) flat slab that includes recycled plastic hollow spheres (RPHS) in its core for decreasing its dead weight. However, punching capacity of BD slabs can be a critical aspect, thereby this work is devoted to assess experimentally its punching behavior. An experimental program composed of four...
Article
The post-cracking tensile properties of steel fiber reinforced concrete (SFRC) is one of the most important aspects that should be considered in design of SFRC structural members. The parameters that describe the post-cracking behavior of SFRC in tension are often derived using indirect methods combined with inverse analysis techniques applied to t...
Article
Full-text available
The behaviour of masonry elements under in-plane loads can be improved by using strengthening overlays. However, the changes in stiffness of the elements after strengthening may have various effects at the level of the behaviour of the entire structure. Advanced numerical simulations can be a helpful and cost effective strategy to guide the efficie...
Article
An experimental campaign was carried out to assess shear creep behaviour of a rigid low-density closed-cell polyisocyanurate (PIR) foam. Two service temperature values were considered, 20 °C and 30 °C, and the applied stresses ranged between 20% and 60% of the corresponding shear strength. The results showed that a stress amplitude of 30% was enoug...
Conference Paper
Full-text available
One of the main concerns of using structural composites as an effective technique for strengthening and rapid restoration of concrete structures is the behaviour of these systems in fire condition. Epoxy resins are currently used to bond structural composites to concrete substrate, but the vulnerability of their properties to high temperatures can...
Article
This paper presents an experimental research program on the punching strengthening of flat reinforced concrete (RC) slabs with carbon fibre reinforced polymer (CFRP) systems. The strengthening system consists of CFRP wet layup sheets that are installed into holes opened orthogonally to the RC slab, and bonded to the surrounding substract with epoxy...
Article
Being immune to corrosion, and having a tensile strength up to three times higher than structural steel, glass fiber reinforced polymer (GFRP) bars are suitable for reinforcing concrete structures exposed to aggressive environmental conditions. However, a relatively low elasticity modulus of GFRP bars (in respect to the steel) favors the occurrence...
Conference Paper
p>Torsional strengthening of thin walled tubular reinforced concrete elements, such as bridge box girders and spandrel beams, has received only limited attention, and investigations generally focus on the use of conventional strengthening methods such as span shortening, steel encasing, member enlargement, shotcrete etc. However, research on the us...
Article
In this work, a computational model for simulating the relevant mechanisms governing the pull-out of a discrete reinforcement embedded into cement based materials is described. The model accounts for the material and geometric properties of the reinforcement, which can include an anchored end, the interface between reinforcement and surrounding med...
Article
Full-text available
Resumo Neste trabalho dois microconcretos, com e sem metacaulinita, foram dosados para produção de compósitos laminados reforçados com fibras longas de sisal. Para garantir uma matriz livre de hidróxido de cálcio foi determinado o teor ideal de metacaolinita por análise termogravimétrica de pastas com teores de substituição de 20%, 30% e 40 nas ida...
Article
This paper describes the development of an integrated design approach for determining shear capacity of flexurally reinforced steel fibre reinforced concrete members. The approach considers fibre distribution profile, fibre pull-out resistance and the modified compression field theory integrated using a comprehensive strategy. To assess the perform...