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January 1989 - present

## Publications

Publications (151)

Steel corrosion in RC structures leads to a reduced reinforcement area, changes in steel mechanical properties, cracking and, eventually, concrete cover spalling, among other phenomena. Stirrups are generally small in diameter and, given their small concrete cover, they are more susceptible to corrosion than longitudinal reinforcement. Hence their...

A mechanical model has been developed by the authors in order to predict the shear strength of reinforced concrete slabs under concentrated loads close to linear supports. The model takes into account a significant number of variables involved in the phenomenon, such as the clear shear span, the concrete compressive strength, the reinforcement rati...

This paper presents the results of an experimental campaign carried out to investigate the effects of in‐plane transverse tensile forces on the shear strength of linearly supported one‐way reinforced concrete (RC) slabs without shear reinforcement subjected to concentrated loads. A total of 5 half scale slabs (1650 × 1650 × 120 mm), subjected simul...

Corrosion reduces the area of reinforcement steel, affects its mechanical properties, the bond properties, and produces concrete cracking. Thus, reduction of the bearing capacity and stiffness, increments of deflections and redistribution of stresses and internal forces, in statically indeterminate structures, take place. In addition, the efficienc...

This paper presents a study of the shear capacity of reinforced concrete (RC) beams strengthened in shear with externally bonded (EB) fiber reinforced polymer (FRP) composites, based on the performance of existing published tests. The main objective of this study is to create a comprehensive overview of the performance of different shear strengthen...

Deflections are among the most complex aspects of reinforced concrete behavior. Furthermore, deflection control is increasingly a governing criterion in design, especially in the case of two-way members such as flat slabs or edge-supported slabs. However, simple and theoretically sound and adequately verified methods for calculating deflections of...

RC slabs can be subjected simultaneously to transverse loads and in-plane tensile forces, as it happens in top slabs of continuous box girder bridges decks, in the regions of negative moments, or in flat slabs subjected to horizontal loads, produced by wind or earth pressure. Tensile forces can reduce the shear punching capacity of slabs. However,...

This paper presents an analysis of the performance of different existing formulations to quantify the FRP contribution to the shear strength of RC elements strengthened in shear by externally bonded FRP sheets. A large database of 555 tests has been assembled distinguishing between the shape of the section, the existence of internal transverse rein...

An experimental campaign on corroded post-tensioned concrete beams is being carried out at the University of Messina (Italy). The main goal of the research project is to study the influence of the tendon corrosion on the response behaviour of post-tensioned concrete beams subjected to a transversal load. In 2006, six beams were cast with a tendon p...

Some reinforced concrete slabs are subjected simultaneously to concentrated loads and unidirectional in‐plane tensile forces. This the case of the top slab of a box girder bridge where hogging bending moments take place at the intermediate supports. Then, the in‐plane tensile forces may reduce the punching‐shear strength under concentrated loads. T...

Although the shear fatigue behaviour of elements without shear reinforcement has been studied for a while, there is still a need for a simple mechanical model that evaluates the shear fatigue strength. The Compression Chord Capacity Model (CCCM), previously developed by the authors, is a simplified model for the shear strength prediction of reinfor...

Shear strength of non-slender reinforced concrete beams, in which a/d ≤ 2.5, is enhanced due to arching action. Current shear design methods for such elements, including the strut-and-tie method (STM), show deviations with respect to tests results. In this paper, a shear strength mechanical model developed for slender beams is extended to non-slend...

Shear in beams and punching shear in slabs, is a long-time hot topic for design and safety evaluation. Due to the brittle behavior in shear of the reinforced concrete (RC) and prestressed concrete (PC) members, the assessment of existing structures must be carried out using reliable models, and, if possible, models based in the mechanical principia...

Shear design of reinforced concrete beams with T section considers only the contribution of the web, mainly provided by aggregate interlock. However, as the load increases and large web crack openings take place, aggregate interlock reduces and shear stresses tend to concentrate near the neutral axis, usually located in the flanges of T beams, whos...

The use of high strength materials allows flexural members to resist the design loads or to cover long spans with a reduced depth. However, the strict cross section dimensions and reinforcement amount required in ULS are often insufficient to satisfy the serviceability limit states. Due to the complexity associated to a rigorous computation of defl...

The corrosion of steel reinforcement is commonly believed to be the primary cause of structural deterioration of reinforced concrete (RC) structures; as a result of this deterioration, a RC structure can incur a considerable reduction in structural serviceability and safety. Because of their inherent redundancy, statically indeterminate structures...

An experimental program of T-beams strengthened in shear by CFRP sheets has been developed with two longitudinal reinforcement ratios and different externally bonded CFRP shear strengthening amounts in a discontinuous or continuous U-shaped configuration with and without mechanical anchorages. The effectiveness of the external reinforcement without...

Fibre reinforced polymers (FRP) bars and steel fibres (SF) are progressively used as alternative or complementary reinforcements for concrete elements to increase, among other aspects, their durability, toughness or shear strength. In order to design RC elements with these non-conventional reinforcements, their effects on the shear resistant mechan...

A punching shear strength mechanical model for RC flat slabs with and without shear reinforcement, based on a beam shear model previously developed by the authors, is presented. The differences in resisting actions between beam shear and punching shear have been identified and incorporated into the governing equations and failure modes, resulting i...

Nowadays, the real application of fibre reinforced polymer (FRP) bars in slabs or in bridge decks submitted to environments susceptible of corrosion is very limited. In spite of its cost, one of the reasons might be the limited knowledge about the punching-shear behaviour of this type of elements in their connection slab-column or under point loads...

Shear strength of a reinforced or prestressed concrete beam results from the interaction of different resisting actions. The model described in the article is a simplification of the multi-action shear model developed by the authors. Presented equations were simplified for submission to ACI-ASCE Joint Committee 445, Shear and Torsion, considering d...

A description of the deformations and damage that occurred in a segmental tunnel lining as a consequence of an unplanned surface load is presented, as well as the numerical analyses performed for its safety assessment. The tunnel in study is located in soft soil conditions and presents a low overburden. Few months after tunnel drilling, a new bridg...

In this paper, a fibre beam model previously developed by the authors for the nonlinear analysis of strengthened elements, including the effects of shear, is used to predict the response of reinforced concrete (RC) beams strengthened in shear with fibre reinforced polymers (FRP) sheets. This model has been extended not only for wrapped configuratio...

The shear resisting actions in reinforced concrete elements without transverse reinforcement is analyzed by means of optimized strut-and-tie models with concrete ties. Biaxial failure criteria are used for uncracked and cracked regions. The stress transfer capacity across cracks is accounted for by including the inclination between the stress field...

AbstractUnder general seismic loading, reinforced concrete columns may be subjected to lateral loads in more than one direction. Available experimental data on columns subjected to bidirectional forces indicate that higher levels of damage and a higher loss of ductility and strength have been observed compared to similar tests under unidirectional...

Understanding the mechanical effects of the corrosion pits on the steel surface requires an accurate definition of their geometry and distribution along the rebar. 3D optical measurement technique is used to obtain the outer geometry of artificially corroded bars tested under cyclic or monotonic loads. 3D FEM model development from the 3D scanning...

A simplified mechanical model for the shear strength prediction of reinforced and prestressed concrete members with and without transverse reinforcement, with I, T or rectangular cross section is presented. The model, derived after further simplifications of a previous one developed by the authors, incorporates in a compact formulation, the contrib...

This work presents the numerical analysis of the RG8 test performed by the French research program Concrack2 in 2011. It consisted in a large RC beam specimen loaded in bending after restrained shrinkage. The specimen is composed of a central thinner part and two massive heads linked by two cylindrical struts that restrained strains due to thermal...

Time-dependent strains, when restrained, can lead to important tensile forces and damage, affecting, among other aspects, the shear response and ultimate load carrying capacity of shear-critical RC frames. This paper presents a detailed study of this problematic by means of an extension of a shear-sensitive fibre beam model to time dependent behavi...

This experimental study assesses the bond performance of recycled aggregate concretes (RAC) with embedded uncorroded and corroded steel bars. The RAC were produced using 20%, 50% and 100% of coarse recycled aggregates obtained from the crushing of waste 40 MPa compressive strength concrete. Three degrees of corrosion were reached on the steel bars....

Safe and economical design and assessment of reinforced (RC) and prestressed concrete (PC) beams requires the availability of accurate but simple formulations which adequately capture the structural response. In this paper, a mechanical model for the prediction of the shear-flexural strength of PC and RC members with rectangular, I, or T sections,...

Steel corrosion in reinforced concrete structures produces loss of reinforcement area and damage in the surrounding concrete. As a consequence, increases in deflections, crack widths and stresses may take place, as well as a reduction of the bearing capacity, which depends on the structural scheme and redundancy. In this paper an experimental study...

In this paper, a fiber beam model previously developed by the authors for the nonlinear analysis of strengthened elements, including the effects of shear, is used to predict the response of reinforced concrete (RC) beams strengthened in shear with fiber reinforced polymers (FRP) sheets. In the previous version of the model, debonding failure of FRP...

Corrosion of steel reinforcement is one of the most severe problems of durability in reinforced concrete structures. A good understanding of the corrosion effects on the reinforcing steel mechanical properties is necessary to adequately assess impaired structures. A study of the mechanical response of corroded reinforcement subjected to monotonic a...

This paper presents an experimental study on the flexural and shear behavior of reinforced concrete beams with a fines content (275 kg/m3) higher than the limit value allowed by the Spanish Concrete Code EHE-08 (175 kg/m3). In the studied range, the fines content scarcely affected the flexural response. The shear strength of the beams with a high c...

A simple but accurate mechanical flexural-shear model for reinforced and/or prestressed members both with and without stirrups and with rectangular or T-shaped cross-section is presented and validated with the recently published ACI-DAfStb databases, with a very low scatter. If the proposed formulation is used for the assessment of existing structu...

A mechanical model previously developed by the authors for the prediction of the shear–flexural strength of slender reinforced concrete beams with rectangular cross-section with or without stirrups has been extended to beams with T and I cross-sections. The effects of the section shape on each shear transfer action have been identified and incorpor...

The shear strength of one-way slabs is studied in this paper via an experimental program performed by the authors and the analysis of a shear test database. The experimental program, in which six slabs and three beams divided into two series were tested, was developed to study the influence of the slab width, the longitudinal reinforcement spacing...

The application of fibre reinforced polymer (FRP) sheets as externally bonded reinforcement in shear for RC structures is less extended than other strengthening applications, because of the complexity of the resisting mechanisms. In addition, in the case of U-shaped or side bonded configurations, the debonding mechanism of the laminates diminishes...

Strengthening reinforced concrete (RC) elements critical to shear with prestressed transversal reinforcement can be an efficient method to increase the shear resistance of structures, allowing the development of the full flexural capacity. However, research on the performance of this technique is very limited, and methods for designing the optimum...

A mechanical model is presented for shear-flexural strength of slender reinforced concrete beams under concentrated or distributed loads. The model incorporates the shear transferred by the un-cracked concrete head, by the cracked web and by the longitudinal and transverse reinforcements. Failure is assumed to occur at the un-cracked concrete zone,...

A mechanical model for the prediction of the shear strength of reinforced concrete (RC) beams with longitudinal and transverse FRP reinforcement is presented. The model assumes that in FRP RC beams, the shear force is taken by the un-cracked concrete chord, by the residual tensile stresses along the crack length and by the FRP stirrups. Failure is...

A mechanical model recently developed for the shear strength of slender reinforced concrete beams with and without shear reinforcement is presented and extended to elements with uniformly distributed loads, specially focusing on practical design and assessment in this paper. The shear strength is considered to be the sum of the shear transferred by...

O atual interesse pelo pré-esforço parcial é, em parte, motivado pelo recente desenvolvimento de novos códigos de dimensionamento baseados no desempenho. No entanto, o comportamento não linear dos elementos de betão parcialmente pré-esforçado (BPP) dificulta a sua aplicação na prática. Apesar dos progressos observados no estado de conhecimento, exi...

Assessing the structural performance of existing concrete bridges is nowadays a major task. Nonlinear finite element analysis (NLFEA) can quantify their capacity, evaluate strengthening interventions and prevent premature dismantle. However, this technique, mainly performed with 2D/3D FE, is seldom used at true scale due to the great complexity and...

A conceptual model for the prediction of the shear-flexural strength of slender reinforced concrete beams with and without transverse reinforcement is presented. The model incorporates the shear transferred by the un-cracked concrete chord, along the crack’s length, by the stirrups, if they are, and, in that case by the longitudinal reinforcement....

Purpose
– A nonlinear finite element (FE) beam-column model for the analysis of reinforced concrete (RC) frames with due account of shear is presented in this paper. The model is an expansion of the traditional flexural fibre beam formulations to cases where multiaxial behaviour exists, being an alternative to plane and solid FE models for the nonl...

Cracking is an inherent characteristic of RC structural behaviour and its control is an important concern for durability and sustainability. The French national research program CEOS.fr – ‘Behaviour and assessment of special construction works concerning cracking and shrinkage’ – has carried out an experimental campaign focused on cracking behaviou...

The safety of existing bridges can be studied through nonlinear numerical models, assisting decisions of dismantle, repair or change of use and avoiding unnecessary or inappropriate interventions. Filament beam models due to their simplicity and low computational demand are adequate for the engineering practice as an alternative to 2D and 3D FEM. I...

Assessment, upgrading and strengthening of ageing civil infrastructure is a major task for Europe. The aim is to extend the life-time of existing concrete bridges without loss of safety. Nonlinear finite element analysis (NLFEA) can quantify the reserve capacity of existing structures and prevent premature dismantle; however, this technique is stil...

The Spanish Structural Concrete Code EHE‑08 was the result of a review in deep of the previous code EHE‑98. A large number of modifications aimed to adapt the Spanish Code to the current European Code framework and the current state of knowledge, to promote the improvement of the quality of the work without unjustified additional costs and to contr...

A simple and rational model for the prediction of the shear strength of FRP reinforced concrete beams without shear reinforcement is presented. The method is based on the principles of structural mechanics and on the experimentally observed behavior of RC beams at shear-flexural failure. It is assumed that, just before failure, the shear is resiste...

The objective of this paper is to contribute to the understanding of the shear resisting mechanisms in RC beams shear-strengthened by externally bonded fiber-reinforced polymer (FRP) sheets. For this purpose, a fiber beam model of RC frames subjected to combined normal and shear forces, previously developed by the authors, has been extended to incl...

This paper analyzes, both experimentally and numerically, the effect of thermal curing on the evolution of temperatures, rate of temperature rise and cooling, stresses and strengths in reinforced concrete elements. It also describes the experimental program carried out to characterize thermally and mechanically the high strength concrete used in th...

According to the available experimental research related to structures flexurally strengthened by bonding fiber reinforced polymer (FRP) laminates, the laminate debonds in a brittle manner in most tests. This debonding failure usually initiates in the most loaded regions due the effect of intermediate cracks (intermediate crack debonding). From the...

The safety of existing bridges and the efficiency of strengthening measures can be accurately studied through non-linear numerical models, assisting decisions of dismantle, repair or change of use and avoiding unnecessary or inappropriate interventions. In this ambit, filament beam models due to their inherent simplicity and low computational deman...

Most of the existing models to prevent debonding failure in beams externally strengthened by fiber reinforced polymer (FRP) laminates were developed focusing on the short term response. This paper studies the effect of concrete creep on the interfacial shear stresses and consequently, on the debonding failure load. A simplified formulation for the...

This paper provides an overview of serviceability specifications given by the fib Model Code for Concrete Structures 2010 (fib MC2010 [1]). First, the reasons behind crack control and deflection control are discussed, then specific design rules are provided. Simple rules as well as detailed models are also presented.
Numerical examples are provided...

In this paper, a theoretical study of the time-dependent behaviour of FRP (fibre reinforced polymer)-strengthened reinforced concrete (RC) cracked sections subjected to sustained loading is performed. Based on it, a simplified method for the calculation of long-term deflections has been proposed and verified with available experimental results. The...

A nonlinear and time-dependent fibre beam element model able to simulate the response of existing reinforced concrete (RC) frame structures subjected to repair and strengthening interventions is presented in this paper. The relevant attributes of the proposed formulation are: (i) its capability for considering shear effects in both service and ulti...

A study of the effective width of different types of reinforced concrete cross sections /s presented.
The method of analysis used is the finite elements method, using shell elements and beam elements to represent the flanges and web respectively.
One of the objectives of this study is to identify the more significant parameters in the determination...

É apresentado neste artigo um modelo de vigas com discretização da secção em fibras para a análise não linear e dependente no tempo de estruturas porticadas de betão armado e pré-esforçado considerando os efeitos do esforço transverso. A análise evolutiva no domínio do tempo permite avaliar o desempenho de estruturas existentes críticas ao esforço...