Ricardo Carrazedo

• PhD
• Professor at University of São Paulo

This paper significantly extends investigations into internal damping ratios in both undamaged and damaged conditions for normal-strength concretes (NSCs) and high-strength concretes (HSCs). This study examines concretes with compressive strengths ranging from 42 to 83 MPa. Cyclic loads were applied using a servo-controlled hydraulic testing machin...

There are few results about the internal damping ratio of normal and high strength concretes. Hence, this paper presents the expansion of the investigation about internal damping ratio under undamaged and damaged conditions, for usual concretes (NSC) and high strength concretes (HSC). In this way, the study cover a strength range of 42 to 83 MPa. C...

The application of Topology Optimisation (TO) to help in the manufacture of metallic components in highly technological industries has increased recently. To equally benefit from TO, the construction industry must address its specific issues, such as adherence to code requirements and challenges in using cutting-edge software packages in complex jo...

The association between two types of concrete at different stages is common in precast connections, composite beams, and repairs, creating an interface. High-Strength Concrete (HSC) is extensively used in precast industries. Ultra-High-Performance Concrete (UHPC) is suitable for filling the HSC-UHPC connection due to its exceptional mechanical prop...

This paper proposes the use of the parametric Krahl–Birtel–Mark constitutive law in Concrete Damage Plasticity (CDP) model, to represent the cyclic behavior of real scale Ultra-high-performance fiber reinforced concrete (UHPFRC) I-beams, with passive and active reinforcements. The accuracy of this constitutive law was evaluated from a numerical val...

Topology optimisation (TO) is increasingly used to assist metallic parts manufacturing in automotive, aerospace, and biomedical sectors. A similar trend is observed in civil engineering structures, particularly in steel construction joints representing crucial steelwork components. Yet, the widespread adoption of TO to steel members in structural e...

This article introduces simulations of theoretical material with controlled properties for the evaluation of the effect of key parameters, as volumetric fractions, elastic properties of each phase and transition zone on the effective dynamic elastic modulus. The accuracy level of classical ho-mogenization models was checked regarding the prediction...

Strain-Hardening Cement-Based Composites (SHCCs) exhibit high toughness and durability, allowing the design of resilient structures. Despite the exceptional properties of SHCC and the current modeling techniques, the widespread use of the composite is limited. One limiting factor is developing and validating analytical models that could be used for...

This article introduces simulations of theoretical material with controlled properties for the evaluation of the effect of key parameters, as volumetric fractions, elastic properties of each phase and transition zone on the effective dynamic elastic modulus (Ed). The accuracy level of classical homogenization models was checked regarding the predic...

To address the meagre use of Topology Optimisation (TO) in the civil engineering industry, the case of bolted moment connections in steel construction has been investigated. Connections are essential in steel structures, contributing up to 25% of the global weight and concentrating the complexity in design and, therefore, the industry's added value...

A norma ABNT NBR 8522 (2021) – Parte 2, recém aprovada, está limitada ao estabelecimento do método de ensaio para determinação do módulo de elasticidade dinâmico do concreto endurecido. Sabe-se, entretanto, que o método das frequências naturais de vibração também pode ser aplicado para a determinação do módulo de cisalhamento e do coeficiente de Po...

Advanced manufacturing has been supported in industries such as automotive, aerospace materials and medical devices, among others, by using Computer-aided Topology Optimisation (TO). However, civil engineering and, mainly, steel construction have been far from experiencing a similar revolution. This can be attributed to the lack of design methodolo...

The importance of connections in steel structures is paramount, not only because it greatly influences the cost of construction and provides room for innovations, but also due to the connections’ impact on global structural behaviour. Therefore, research into innovative connections for seismic applications and related design criteria has significan...

Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) is a cement-based composite with superior mechanical and durability properties compared to conventional concrete. The inclusion of short fibers in the brittle matrix can change the behavior to ductile and tough. Several experimental investigations on the effect of fiber content and orientati...

High-Strength Concrete (HSC) has been used in the production of precast concrete structures while Ultra-High-Performance Concrete (UHPC) has been considered an option for filling the connection between HSC elements due to outstanding mechanical properties and durability. However, it is necessary to investigate how these connections would benefit fr...

The first studies on the dynamic behavior of railway lines go back to the 19th century, after the industrial revolution. Since then, numerous analytical solutions and numerical models have been developed toward understanding the dynamic response of moving loads. However, proposals that reproduce the vibrational behavior of subway lines remain chall...

Ultra-high-performance fiber reinforced concrete (UHPFRC) is a new material developed to present superior properties, as high compressive strength (higher than 130 MPa), high durability, and satisfactory ductile behavior. This paper reports the procedure to design precast UHPFRC beams, subject to flexural loads. First, an I-girder AASHTO Type II wa...

Resumo Propriedade fundamental do concreto, o módulo de elasticidade é utilizado no cálculo das estruturas, especialmente na verificação dos estados limites de serviço, sendo também considerado na norma ABNT NBR 15575 (2013). O módulo de elasticidade ainda é de difícil determinação e fonte de controvérsias entre projetistas, construtoras, empresas...

Ultra High-Performance Fiber Reinforced Concrete (UHPFRC) is a promising material for applications in precast industry characterized by fast construction. However, there is a gap in investigations on the pullout behavior of inclined fibers at different ages. Therefore, pullout tests were performed in UHPFRC at 1d, 3d, 7d, and 28d, with fibers havin...

This paper provides guidelines for cyclic loading bending test simulation and modal analysis of a reinforced concrete I-beam. For this purpose, experimental and numerical cyclic bending test were performed. In the experimental study, the natural frequencies of the structure in the intact and damaged states were measured. The simulation of the cycli...

This paper reports the characterization of internal damping ratio () and Q-factor of Ultra-high-performance fiber-reinforced concrete (UHPFRC) using acoustic tests for undamaged and damaged samples excited by an impact.  is a non-dimensional parameter that measures the material capacity to dissipate vibration, and the Q-factor is physically inter...

O modelo Concrete Damaged Plasticity (CDP), implementado no software de elementos finitos Abaqus, é tipicamente usado para descrever o fissuramento do concreto sob carga mecânica. As leis de endurecimento e amolecimento são descritas pelo comportamento uniaxial de compressão/tração do material e pelas leis de evolução de danos. Os parâmetros de pla...

Deep beams do not behave according to classical beam theory. The nonlinearity of strain distribution within these elements requires application of strut and tie models (STM) or other alternatives to evaluate the complex stress field. Although the design of these elements is a common task for structural engineers, limited research is found on assess...

The research field of constitutive modeling ultra-high performance fiber reinforced concrete (UHPFRC) is in current development. Few experimental results were reported for the material under uniaxial low-cycle loading, and consequently, there is a gap in constitutive propositions to predict its behavior. Thus, one purpose of this research is to pro...

The approach for identifying modal parameters of a structure from power spectral density transmissibility matrices, called the PSDTM-SVD method, is improved to identify modal parameters (including damping ratios) in a condition when the structure is not completely loaded. Therefore, an enhanced PSDTM-SVD method is proposed based on the use of a mod...

In this paper, the finite element method was used for the numerical modeling of columns with square, rectangular and circular cross sections wrapped with FRP. The numerical modeling was successfully calibrated with the experimental data considering axial load, axial strain and transverse strain. The distribution of compressive stresses in the cross...

Leakage resistance of casing connections can be evaluated by extremely expensive testing procedures. Although testing is required for connection validation, significant amount of resources can be saved by complementing testing with Finite Element (FE) analysis. In this regard, a broadly accepted criterion to characterize leaks in FE simulation is s...

Confinement of concrete columns with fiber-reinforced polymer (FRP) laminates has been extensively studied in recent decades due to their important applications for strengthening purposes or construction of hybrid elements. Significant differences were observed in confinement effects obtained for normal-, high-, and ultrahigh-strength concrete when...

The development of a flowable Ultra-High Performance Fiber-Reinforced concrete UHPFRC enables to cast thin precast beams with a reduced self-weight meeting at the same time the required structural and durability performances. However, such slender elements are prone to instability failure when subjected to transitory phases, like lifting. Thus, the...

During construction, concrete beams are susceptible to rollover failure when unbraced and supported by elastomeric bearing pads. This failure occurs mainly due to the presence of initial horizontal curvature of the beam and the low torsional restraint provided by the supports. Besides, the uncertainties and variability about modulus of elasticity,...

Ultra-high performance fiber reinforced concrete (UHPFRC) is a class of cement-based composite with outstanding strength, durability, and ductility. The strain hardening behavior in tension and flexure and the high toughness in compression make the composite a proper material to carry severe cyclic loads, as in earthquakes. However, there are limit...

O Concreto de ultra alto desempenho reforçado por fibras (UHPFRC) é um novo material desenvolvido para apresentar propriedades superiores, tais como alta resistência à compressão (superior a 150 MPa), grande durabilidade, baixa permeabilidade além de comportamento dúctil satisfatório. Atualmente, nota-se a crescente tendência de aplicação deste mat...

Internal damping ratio (ξ) describes the material’s behavior in dynamic conditions and arises from voids, fractures and transition zone. Here, we are reported the extensive investigation about internal damping ratio under variations of water-cement ratio and maturity. Acoustic tests were employed to obtain dynamic elastic modulus (Ed) and internal...

The high ductility and high toughness of ultra-high performance fiber-reinforced concrete (UHPFRC) make the composite a promising material to be applied in earthquake-resistant structures. For this reason, its constitutive behavior must be investigated in advance on seismic strain rates (10-2 s-1), which were not reported for compressive loads yet....

The impact acoustic test is a fast and low-cost nondestructive alternative to evaluate the mechanical properties of concrete. However, the dynamic elastic modulus obtained in this test differs systematically from the static one. The aim of this paper is to study this relationship as well as to identify possible advantages and limitations of impact...

During construction of precast girder bridges, there is the concern on rollover instability of the beams when exclusively supported by elastomeric bearing pads. This type of failure has been the focus of recent research due several accidents reported. However, these studies have not considered the nonlinear behavior of elastomeric bearing pads and...

This study aims to establish relationships between dynamic and static mechanical properties for masonry mortars containing lime. An experimental research was conducted with four mortar mixes of different compositions. Acoustic and compression tests were performed at different ages. Acoustic tests showed lower dispersion and higher elastic moduli th...

Fiber-reinforced polymer (FRP) wrapping has been extensively studied for strengthening reinforced concrete columns. However, few studies were found on the behavior under small eccentric loads, a frequent situation in real-world applications. In this paper an experimental, numerical, and theoretical study on the influence of small eccentricity of lo...

Near Surface Mounted (NSM) Carbon Fiber Reinforced Polymer (CFRP) has shown to be a very effective technique for shear strengthening of reinforced concrete beams. Previous work showed important strength increases due to application of NSM CFRP in undamaged beams. However, few results were found in the literature to show the effectiveness of the tec...

The use of slender sections in precast beams is possible with the use of ultra-high performance fiber reinforced concrete (UHPFRC). This application can reduce considerably the self-weight of the structure and its cost. However, with the significant increase of slenderness, there is concern about the lateral buckling of the beam in transitory and f...

Resonant acoustic tests appeared recently as an interesting nondestructive alternative that can be applied for the determination of elastic properties with low cost and accuracy. Besides, the same sample can be tested repeatedly if necessary, simplifying laboratorial procedures for long term monitoring. This paper presents an experimentally based e...

Concrete confinement has an important role in reinforced concrete columns, especially for strengthening applications and in hybrid construction. It is well known that confinement increases axial strength and ultimate strain of concrete. However, existing confinement models are extremely dependent on the type of confinement, i.e., passive or active;...