Isabel B. Valente

University of Minho · Institute for Sustainability and Innovation in Structural Engineering (ISISE)

This study aims to evaluate the flexural behavior of I-shaped cross-sectional steel-fiber-reinforced concrete (SFRC) beams that are reinforced with prestressed glass fiber reinforced polymer (GFRP) and steel rebars (hybrid reinforcement, HR). The results obtained in the experimental tests on these SFRC beams are compared with those of reinforced co...

Bond between concrete and reinforcement material is crucial for the structural behaviour and design of reinforced concrete or mixed steel-concrete structures. When considering applications in harsh environments, such as severe marine exposure or submerged conditions, hot-dip galvanized (HDG) steel seems to be a promising solution, as part of new mi...

Composite structures and precast solutions stand out because they lead to simple, fast erected and economic constructions. In steel-concrete composite construction, shear connectors are used to assure the shear transfer between the steel profile and the concrete slab, enabling the composite action to develop. This paper discusses an innovative tech...

This article explores the application of the global resistance methods (GRMs) on the design of hybrid glass fiber-reinforced polymer (GFRP) and steel fiber-reinforced concrete (SFRC) beams. Addressing challenges posed by GFRP-reinforced beams, this study aims to assess the impact of material uncertainties on the behavior of such hybrid beams. The i...

Lightweight concrete has as its main advantage the possibility of reducing structures’ weight. In addition, the fact that they have a better-quality transition zone compared to traditional concrete makes these concretes an alternative to improve the durability of structures. Lightweight concrete is essentially made up of binder, aggregates, and wat...

The compressive behavior of steel-fiber-reinforced-concrete (SFRC) is dependent on the loading rate. This research investigates, experimentally and analytically, the effect of loading rate on the compressive behavior of SFRC designed to be used in prefabricated urban protective furniture. For this purpose, cylinder SFRC specimens were subjected to...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

Marine resources are essential to support an ever growing world population and approaches that can foster the growth and survival rates of habitats and promote the sustainability of human activities are seen as urgent. Artificial reefs (AR) or multifunctional artificial reefs (MFAR) are considered promising and viable solutions to increase the numb...

The object of study in this research is the development of an innovative submerged structure for a variety of coastal and offshore structures, nowadays in great demand. These structures share several challenges with an entire new era of maritime structures, mostly related to renewable energies, sea operation, structural complexity, durability needs...

This paper presents a prospective study on the behaviour of steel and concrete composite beams in which a linear indented continuous shear connector, called Crestbond, is used to establish the connection between the steel beam and the concrete slab and ensure the joint behaviour of these two elements. The work includes an experimental campaign deve...

Fábrica do Paleão was erected as a flagship textile factory in Portugal between 1888 and 1891. The factory was constructed with a sawtooth roof supported by iron trusses, allowing light open spaces to accommodate heavy machinery and promote industrial activity. With the aim of preserving this exemplary representative of industrial heritage in Portu...

The Glass Fibre Reinforced Polymer (GFRP) connectors studied in this work were previously proposed by the authors for connecting the outer Steel Fibre Reinforced Self-Compacting Concrete (SFRSCC) layers of sandwich panels for prefabricated modular housing. In this building system, SFRSCC was used to totally eliminate the need for conventional reinf...

In repairing and retrofitting processes of ancient riveted steel bridges is crucial to assess the structural state of old metals to guaranty structural safety. Metals under long-time operations (mild, rimmed low carbon steels < 0.1%í µí° ¶, puddle irons) and cyclic loading present a tendency for degradation processes. The case-studies of this work...

In repairing and strengthening operations of ancient riveted steel bridges is important to estimate and assess the structural degradation of the old metals in order to guaranty the structural safety. Long-time operated metallic materials (mild, rimmed low carbon steels <0.1%C, puddle irons) subjected to cyclic loading show tendency to the microstru...

This paper aims to extend the interpretation of data collected from experimental tests developed to analyze the fatigue phenomena on the material obtained from old Portuguese metallic bridges. The metallic bridges addressed were built in the late nineteenth and early twentieth centuries and have now become important historical heritage. The main ma...

The present paper explores a new modular floor prototype to be used in emergency houses. The prototype is composed of a frame structure made of glass-fibre-reinforced polymer tubular pultruded profiles, a slab made of sandwich panels with a polyurethane foam core and glass-fibre-reinforced polymer skins, and a tailored connection system that provid...

Cast-in-place concrete is often the cheapest solution in the context of conventional construction. However, prefabrication presents advantages in terms of execution time, quality of the structural elements and cost. The association of precast concrete elements and steel sections in a composite element can thus result in a high-quality structure tha...

Throughout this paper, a new system for connecting composite sandwich wall panels is proposed. The relevant structural components are investigated with the aim of utilizing these panels as insulated wall elements in building applications or prefabricated modular systems. The adopted sandwich wall panels are composed of hand-layup glass fiber–reinfo...

The present study intends to evaluate the flexural performance of hybrid sandwich panels through the execution of four point bending tests. The proposed hybrid sandwich panel uses Deflection Hardening Cementitious Composites (DHCC) on the top layer, a GFRP bottom layer and perforated shear connectors in the GFRP ribs to transfer shear stresses betw...

Maintenance of ancient road and railway metallic bridges has become a major concern for governmental agencies in the past few decades. Indeed, since the construction of these structures, between the end of the 19 th century and the beginning of the 20 th century, traffic conditions have evolved, both in weight and frequency. In the purpose to asses...

An innovative hybrid sandwich slab for the rehabilitation of floors in old masonry buildings was conceived, designed, and tested. This structural system is a lightweight composite floor consisting of bottom skin and shear ribs in Glass Fiber Reinforced Polymer (GFRP), a top layer of Deflection Hardening Cement Composites (DHCC), and Polyurethane fo...

A series of experimental tests carried out on a composite prototype to be used as a floor module of an emergency house is presented in this paper. The prototype comprises a frame structure formed by GFRP pultruded profiles, and two sandwich panels constituted by GFRP skins and a polyurethane foam core that configures the floor slab. The present wor...

This paper presents the probabilistic-based assessment of composite steel-concrete structures through an innovative framework. This framework combines model identification and reliability assessment procedures. The paper starts by describing current structural assessment algorithms and the most relevant uncertainty sources. The developed model iden...

A novel framework for probabilistic-based structural assessment of existing structures, which combines model identification and reliability assessment procedures, considering in an objective way different sources of uncertainty, is presented in this paper. A short description of structural assessment applications, provided in literature, is initial...

Companhia Aurifícia is located in Porto, Portugal, and was founded in 1864. It was a pioneer factory in the industrial production, casting, rolling and stamping of metallic objects and laboured for about 150 years, in areas as jewellery, manufacture of parts in silver and gold or the production and casting of various metals. In 1866, it began labou...

By taking advantage of the appropriate use of cement and polymer based materials and advanced computational tools, a pre-fabricated affordable house was built in a modular system. Modular system refers to the complete structure that is built-up by assembling pre-fabricated sandwich panels composed of steel fibre reinforced self-compacting concrete...

In this paper, a new generation of composite sandwich slab is proposed as a solution for the rehabilitation of slabs in old masonry buildings. An innovative solution was developed during this research formed by four components: a Deflection Hardening Cement Composite (DHCC) layer on the top compression skin, a glass fiber reinforced polymer (GFRP)...

This paper presents the results of an experimental program developed to investigate the behavior of an innovative technology for connections by adhesion, interlocking and friction in composite structures. Connections have a strategic importance for precast concrete and steel–concrete composite structures, since they determine the global structural...

Neste trabalho apresenta-se um algoritmo avançado para avaliação da segurança de pontes existentes. Esta ferramenta inclui dois componentes principais: (i) um modelo de identificação de parâmetros; (ii) a avaliação de segurança baseada em análise probabilística, com atualização dos parâmetros do modelo. No primeiro componente, é usado um algoritmod...

Neste trabalho apresentam-se os resultados de um programa experimental realizado num protótipo destinado a habitações de emergência, tendo como objetivo fundamental o estudo do comportamento estrutural, incluindo a determinação de parâmetros modais, dos painéis sanduíche nelas utilizados. O protótipo é constituído por painéis sandwich com lâminas d...

Laje sandwich em polímero reforçado com fibra de vidro e argamassa de ultra elevada ductilidade para a reabilitação estrutural SUMÁRIO Neste trabalho apresenta-se um novo sistema estrutural em laje sandwich formada por camada inferior de tração e nervuras transversais em material polimérico reforçado com fibra de vidro (GFRP), núcleo em material le...

De las diferentes técnicas existentes en refuerzo de pilares de hormigón armado, el uso de angulares y presillas metálicas, ha sido y sigue siendo, una de las técnicas más utilizadas. Sin embargo, todavía a día de hoy no existe una metodología totalmente aceptada sobre cómo debe diseñarse y comprobarse un refuerzo empleando esta técnica. En este ar...

In the first part of this paper the authors describe an innovative sandwich panel that comprises Glass Fibre Reinforced Polymer (GFRP) connectors and two thin layers of Steel Fibre Reinforced Self-Compacting Concrete (SFRSCC). This second part of the paper reports the investigation performed by the authors based on the numerical simulation of these...

In this paper, an innovative and thermally efficient sandwich panel is proposed for the structural walls of a pre-fabricated modular housing system. Traditionally, sandwich concrete panels consist of reinforced concrete wythes as outer layers, polystyrene foam as core material and steel connectors. However, steel connectors are known to cause therm...

Paradela Bridge is a metallic bridge located along the bank of the Tua River in northern Portugal. While the bridge is not currently in service, its structure is representative of many metallic truss structures built across the continent between the XIX and the XX century. Tua Line belongs to the Douro area that UNESCO recently declared as world he...

This paper presents the first part of a numerical study to simulate composite beam to reinforced concrete wall joints using the finite element software ABAQUS. In detail, several benchmark examples dealing with different components of the joint are simulated in the validation and calibration process of the finite element package. Moreover, these si...

The PERFOFRP connector consists on a perforated glass fibre reinforce polymer (GFRP) rib that is specially designed to perform the connection between thin concrete layers, which can be also useful in the context of structural rehabilitation. It stays embedded in the concrete layers, avoiding the use of complementary connecting techniques, like spec...

In this paper, a new generation of composite sandwich panel slab is proposed as a solution for the rehabilitation of slabs in old masonry buildings. The new slab composite system is composed of four elements that include: High Performance Fiber Reinforced Concrete (HPFRC) layer, GFRP ribs, foam core and GFRP skin. An innovative GFRP-HPFRC hybrid so...

Nonlinear numerical models are considered to be more accurate because they furnish a realistic representation of the structure under analysis. Moreover, it is known that different uncertainty sources should be considered when evaluating structure behaviour. Therefore, probabilistic based models, which consider the structural properties as distribut...

This paper presents the second part of a numerical study that aims to reproduce the behavior of a novel type of joint between a composite beam and reinforced concrete wall using the finite element software ABAQUS. The joint configuration was developed within the RFCS project “InFaSo”, which provided the experimental results. In a preceding paper, t...

A design model for composite beam-to-reinforced concrete wall joints is presented and discussed in this paper. The model proposed is the component method extended to this type of joint. The characterization of the active components is therefore performed in terms of force-deformation curves. In this type of joint, special attention is paid to the s...

Paradela Bridge is a metallic bridge located along the bank of the Tua River in northern Portugal. While the bridge is not currently in service, its structure is representative of many metallic truss structures built across the country between the 19th and the 20th century. The construction of the Paradela Bridge was completed in 1886 and served fo...

A utilização de compósitos poliméricos reforçados com fibras (FRP) mostra-se bastante competitiva em aplicações específicas de engenharia civil. No caso de elementos estruturais mistos, de que são exemplo os painéis sandwich constituídos por duas lâminas de betão separadas por uma camada de isolamento ou as vigas mistas com perfil em FRP e laje de...

ABSTRACT: Life cycle analysis (LCA) of civil structures is a framework which helps owners deciding whether or not a specific action is the most suitable in each time instant. This decision will always depend up- on the curve risk vs. cost. Risk is the product of the probability of a specific limit state happens per its conse- quence. This probab...

The life cycle analysis (LCA) of structures is a framework that evaluates its condition and safety within the whole life through specific performance indicators. Management decisions are then taken considering this state and in a way that cost is optimized. Used indicators are strictly correlated and they are usually determined through a structural...

ABSTRACT: Despite the intensive experimental and numerical research focused on the behavior of steel and lightweight concrete composites, there are still significant uncertainties related to the materials and shear connection behavior. This paper analyzes one composite beam that was previously loaded up to failure in a laboratory experimental te...

ABSTRACT Lifetime assessment of civil engineer structures is a framework which helps operators in performing its maintenance by evaluating their behaviour during the whole life. In order to do so, a numerical model, which should be a good representation of reality, is usually considered. This paper presents a methodology, based in numerical ide...

Insulated sandwich wall panels are frequently composed of external concrete layers, mechanically connected through metallic connectors, such as trusses. Due to their high thermal conductivity, these connectors generally cause thermal bridges on the building envelope. In view of this problem, an innovative system is proposed where FRP connectors are...