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Article
Publication date: 10 November 2021

P.A. Montenegro, José A.F.O. Correia, Abilio M.P. de Jesus and Rui A.B. Calçada

266

Abstract

Details

International Journal of Structural Integrity, vol. 12 no. 6
Type: Research Article
ISSN: 1757-9864

Article
Publication date: 11 June 2018

Patricia Raposo, Michael Andrade, José Correia, Maria E. Salavessa, Cristina Reis, Carlos Oliveira and Abilio M.P. de Jesus

The case-study building of this work is the Medieval Inn of Gralheira (“Pousada Medieval da Gralheira”) located in Vila Pouca de Aguiar, Portugal. This building is an example of…

Abstract

Purpose

The case-study building of this work is the Medieval Inn of Gralheira (“Pousada Medieval da Gralheira”) located in Vila Pouca de Aguiar, Portugal. This building is an example of the structures of that time, located in Trás-os-Montes, Portugal. A large amount of the built heritage suffers from advanced degradation, making the recovery, increasing the complexity of the rehabilitation and restoration intervention and implying a highly specialized interdisciplinary component. Therefore, the purpose of this paper is to carry out a study of the building in order to perform an analysis of its wood floor and assess its structural behaviour and conservation status. This work also presents some examples of intervention methods and rehabilitation techniques used to solve problems in the masonry structure and wood structures.

Design/methodology/approach

In this work, a numerical model of a wood pavement of a medieval building is presented, which was developed and calibrated with values obtained in an experimental campaign of wood specimens extracted from the floor structure and the deformation measured in situ. This model aims to analyse and predict the behaviour of the structure in terms of serviceability limit states. Rehabilitation and reinforcing techniques are described, for specific damages, complemented with a critical comparative analysis to define the most appropriate rehabilitation measures for each situation.

Findings

In this work, for the numerical model of the medieval building under consideration, the support of the beams in the walls between 50 per cent embedded and simply supported (hinge supports) was used. Since the beams have some restriction imposed by the wall, they have a delivery about 20 cm in the wall. The consideration of the delivery between beam and columns as simply supported (hinge supports) is a reasonable approximation. There is a difference between the values of deformation obtained in the numerical model and in situ due to the support conditions and also due to the consideration of the pavement loads as a distributed load, which does not correspond entirely to reality, since the pavement confers rigidity to the floor, behaving like a diaphragm. The presented intervention techniques are not applicable in all structures because each building has different characteristics, in terms of materials and construction. The pathologies occur due to many sources and each case is unique, and must be carefully studied before taking decisions about the rehabilitation methods to use.

Originality/value

This work presents a numerical model of wood pavement of a medieval building developed according to some experimental values obtained in an experimental campaign using wood specimens extracted from original beams and based on in situ measurements. This study is part of master thesis of Michael Andrade, an original research work.

Details

International Journal of Structural Integrity, vol. 9 no. 3
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 11 June 2018

Regina C.G. Leite, Abilio M.P. de Jesus, José Correia, Patricia Raposo, Renato N. Jorge, Marco Paulo Parente and Rui Calçada

Recent studies have proposed the application of local fatigue approaches based on fracture mechanics or on strain-life material relations for the fatigue analysis of metallic…

Abstract

Purpose

Recent studies have proposed the application of local fatigue approaches based on fracture mechanics or on strain-life material relations for the fatigue analysis of metallic structures. However, only few studies in the literature apply local approaches in the riveted bridges analysis; although these approaches can be applied to any type of connections, requiring a detailed stress analysis of joints and, consequently, considerable computational resources costs. The approach based on S-N curves, formulated in nominal or net stresses, is more usual in the fatigue analysis of riveted bridges. Due to economic factors, riveted bridges have had their operating life extended, while changes in the transport system over the years have subjected such structures to overloads different from those originally planned. These bridges, most of them centenary, were not originally designed accounting for fatigue damage; they represent an important group of structures that are very likely subjected to significant fatigue damage indexes. These factors make necessary detailed residual fatigue life studies to substantiate the decisions of extend (or not) the operational period of these bridges. The paper aims to discuss these issues.

Design/methodology/approach

The present paper presents a methodology aiming at applying the local approaches in the fatigue analysis of riveted joints of metallic bridges, through the use of sub-modeling techniques and procedures automation. The use of such techniques made such an application viable by keeping the computational costs involved at a moderate level. The proposed procedures were demonstrated using the Trezói Railway Bridge, located on the Beira Alta line, Portugal, built shortly after the Second World War. The proposed set of procedures allowed, through finite elements analysis, to obtain the relevant stresses to perform local fatigue damage analysis. A global structural model was constructed, using beam elements, and local models of a critical node were built with solid finite elements. The structure is analyzed under the passage of regulatory trains. The details of the modeling performed and the computation of the principal stresses in the vicinity of a node and the tangential/circumferential stresses at the holes of two critical riveted connections of that node are analyzed and a fatigue damage analysis is carried out.

Findings

In the proposed submodelling approach, disassembling the complex riveted nodes into riveted subassemblies allowed the evaluation of the local stresses at riveted holes at an affordable computational cost.

Originality/value

A methodology is proposed to allow the application of local fatigue analysis in real complex riveted joints, mitigating the computational costs that would result from a full model of the node with all rivets.

Details

International Journal of Structural Integrity, vol. 9 no. 3
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 11 June 2018

Patricia Raposo, João Martins, José Correia, Maria E. Salavessa, Cristina Reis, José Xavier and Abilio M.P. de Jesus

The antique structures are part of the inheritance that our elders left, being important to preserve their memories. It is important to preserve, rehabilitate and restore the…

Abstract

Purpose

The antique structures are part of the inheritance that our elders left, being important to preserve their memories. It is important to preserve, rehabilitate and restore the historic buildings protecting the cultural patrimony, attending to the actual comfort and habitability requirements. It is necessary to study the behaviour of the various elements that compose antique structures (masonry and wood) in order to develop assessment measures according to the characteristics of the original materials. The paper aims to discuss these issues.

Design/methodology/approach

An experimental campaign to characterize the mechanical behaviour of the wood of the roof of the “sequeiro” of “Quinta Lobeira de Cima”, a building from the twentieth century located in Minho, was carried out. The tested wood specimens are from two different species: chestnut and oak. Compression, tension and static flexion tests according to parallel to the grain direction were performed. Other parameters, such as density, moisture content and longitudinal modulus of elasticity in compression and in tension, were also obtained. The measurement of displacements was made with Digital Image Correlation (DIC).

Findings

The results of this study show the similarity between experimental and empirical values for the studied woods species.

Originality/value

This original study aimed at characterizing the mechanical properties using DIC of wood of the roof of the “sequeiro” of “Quinta Lobeira de Cima”, a building from the twentieth century located in Minho (Portugal). This study is part of master thesis of João Martins, an original research work.

Details

International Journal of Structural Integrity, vol. 9 no. 3
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 8 August 2020

Tayeb Kebir, José Correia, Mohamed Benguediab and Abilio M.P. de Jesus

The purpose of this scientific work is to simulate the fatigue damage under random loading taking into account the mean stress effect on fatigue lifetime and using the rainflow…

Abstract

Purpose

The purpose of this scientific work is to simulate the fatigue damage under random loading taking into account the mean stress effect on fatigue lifetime and using the rainflow counting technique to assess the fatigue damage.

Design/methodology/approach

The study of fatigue under random loading is based on same concepts which as constant loading with addition of damage summation. The damage of materials due a stress cycle depends not only on the alternating stress but also on the mean stress.

Findings

The cycles counting simulation method allows quantifying the hysteresis loops, even if for small amplitude stresses.

Originality/value

The cycles are low or medium; the damage occurs most often, the higher values of alternating stresses cause the most failure of materials.

Details

International Journal of Structural Integrity, vol. 12 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 1 October 2019

Cristiane Oliveira Viana, Hermes Carvalho, José Correia, Pedro Aires Montenegro, Raphael Pedrosa Heleno, Guilherme Santana Alencar, Abilio M.P. de Jesus and Rui Calçada

The purpose of this paper is to evaluate the fatigue process through the dynamic analysis of the global structural model and local static sub-modelling in a critical detail using…

Abstract

Purpose

The purpose of this paper is to evaluate the fatigue process through the dynamic analysis of the global structural model and local static sub-modelling in a critical detail using the hot-spot stress approach. The detail was studied in three different positions at the “Alcácer do Sal” access viaduct, and the methodologies from the IIW and Eurocode EN 1993-1-9 were compared.

Design/methodology/approach

In this study, the fatigue life process based on the hot-spot stress approach was evaluated using a global dynamic analysis and a local sub-modelling based on a static analysis of welded connections in the “Alcácer do Sal” railway structure, Portugal, taking into consideration the recommendations from IIW and Eurocode EN 1993-1-9. The hot-spot stresses were calculated through the static analysis of the sub-model of the welded connection for each vibration mode with the aim to obtain the temporal stresses using the modal coordinates and modal stresses of the extrapolation points. The Ansys® and Matlab® softwares were used for the numerical analysis and the hot-spot stress calculations, respectively.

Findings

The proposed methodology/approach to obtain fatigue assessment is based on the modal analysis of the global structural model and local static sub-modelling. The modal analysis was used to extract the boundary conditions to be used in the local model to determine the temporal stresses of the extrapolation points. Based on the modal superposition method, the stresses as function of time were obtained for fatigue life evaluation of a critical detail by the hot-spot stress approach. The detail was studied in three different positions.

Originality/value

In the present study, a global-local fatigue methodology based on dynamic analysis of the global structural model and local static sub-modelling of the critical detail using the hot-spot stress approach is proposed. Herein, the modal analysis of the global structural model supported by the modal superposition method was used to obtain the matrix of modal coordinates. The static analysis of the local sub-model for each mode from the modal analysis of global structural model was done to estimate the hot-spot stresses. The fatigue damage calculation was based on S-N curve of the critical detail and rainflow method. The IIW recommendation proved to be more conservative compared to the proposed rules in the Eurocode EN 1993-1-9. The global-local modelling based on dynamic analysis is an important and effective tool for fatigue evaluation in welded joints.

Details

International Journal of Structural Integrity, vol. 12 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 11 June 2018

Grzegorz Lesiuk, Mikolaj Katkowski, José Correia, Abilio M.P. de Jesus and Wojciech Blazejewski

The purpose of this paper is twofold: first, to observe an influence of different Composite Fibre-Reinforced Polymer (CFRP) patches, whose application to metals is very easy, in…

Abstract

Purpose

The purpose of this paper is twofold: first, to observe an influence of different Composite Fibre-Reinforced Polymer (CFRP) patches, whose application to metals is very easy, in suppling and significantly elongating the service time; and second, the numerical calculation of the reduced stress intensity factor (SIF) range for strengthened cracked steel specimens.

Design/methodology/approach

One of the successful strengthening methods is the CFRP patching along the fatigue crack paths. The presented approach has been studied and discussed in this paper on the background of the numerical and experimental data. As it was expected, the proposed strengthening method is efficient and promising in case of the “immediate” repairs of critical members with cracks. The manufacturing process of specimens and test methodology as well as numerical approach to calculate SIFs for various reinforcements of steel specimens are presented. For this purpose, the Extended Finite Element Method was involved and described.

Findings

The main mechanism of fatigue crack growth retardation is associated with local ΔK reduction due to CFRP patches; any type of reinforcement results in an increase in af and a significant decrease in SIF values. The beach-marking method is described as a good, reliable and comprehensive method to capture the crack propagation in structures consisting of various materials and could be applied successfully for mixed mode testing.

Originality/value

A detailed experimental-numerical approach for fatigue crack growth in long-term operated structures made of steel is presented. The strengthening methodology is presented with consideration of the various CFRP patches configurations.

Details

International Journal of Structural Integrity, vol. 9 no. 3
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 11 June 2018

Halyna Krechkovska, Oleksandra Student, Grzegorz Lesiuk and José Correia

The purpose of this paper is to assess the technical state of old and repair steels of Shukhov’s tower elements after operation during ~ 110 and 70 years of the water tower in…

Abstract

Purpose

The purpose of this paper is to assess the technical state of old and repair steels of Shukhov’s tower elements after operation during ~ 110 and 70 years of the water tower in Nikolaev, basing on their mechanical tests, metallography and fractography investigations.

Design/methodology/approach

For their certification, the fractographic and structural features and mechanical properties (hardness, strength, plasticity and impact toughness) were analyzed. Both the steels under consideration were characterized by low values of hardness and brittle fracture resistance. The mechanical characteristics of the old steel are lower compared with the repair one. It cannot be only explained by the quality of metal rolling. Moreover, the plasticity characteristics of both steels, defined in synthetic acid rain environment, are lower than in the air. Using fractography investigation, the operational damages in the bulk metal in the form of the elements of cleavage fracture in the central part of the fracture surfaces of specimens tested at the hydrogenation condition by synthetic acid rain environment were revealed.

Findings

The results of this study suggested a degradation of steels’ characteristics caused by the development of scattering damages during their operation. Higher relative elongation of the old steel at lower hardness and impact toughness were also evidenced in that. The metallography and fractography investigations also supported this finding.

Originality/value

This original study aimed at characterizing the microstructural and mechanical degradation of mild steels that was collected from Shukhov’s tower structural elements.

Details

International Journal of Structural Integrity, vol. 9 no. 3
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 5 November 2019

Michał Smolnicki, Mateusz Cieciura, Grzegorz Lesiuk, José Correia and Paweł Stabla

Engineered stone is a material which can be described as an artificial stone. The exemplary application area is sink production. There are very few research projects about this…

Abstract

Purpose

Engineered stone is a material which can be described as an artificial stone. The exemplary application area is sink production. There are very few research projects about this type of material. In fact, most of them are research conducted by the manufacturing company, which are limited to the basic properties of the material. However, knowledge about fracture mechanic of this material may be crucial in terms of usage. The paper aims to discuss this issue.

Design/methodology/approach

Analysis of the inside structure was made using an optical microscope as well as SEM. In the paper, methods which can be used to obtain data about fracture behaviour of material are presented. Using eXtended Finite Element Method and experimental data from three-point bending of notched specimens stress intensity factors (SIFs) for I and II load modes were obtained. Finally, a comparison between the fracture initiation angle in the function of the ration of SIFs for I/II load modes and maximum tangential stress hypothesis prediction was presented.

Findings

Analysis of the inside structure proves that this type of material has an uneven distribution of particle size. This can follow to void and micronotches formation and, later, to the failure of the material. A method of obtaining stress intensity factors for the discussed type of material and specimens can be successfully applied to other similar material, as proposed in this work. Standard crack angle propagation criteria are not sufficient for this type of material.

Originality/value

There are very few research papers about this type of material. The subject of fracture mechanic is not properly discovered, despite the fact that IT is important in terms of the application area of these materials.

Details

International Journal of Structural Integrity, vol. 12 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 11 June 2018

Grzegorz Lesiuk, Monika Maria Duda, José Correia, Abilio M.P. de Jesus and Rui Calçada

For nowadays construction purposes, it is necessary to define the life cycle of elements with defects. As steels 42CrMo4 and 41Cr4 are typical materials used for elements working…

Abstract

Purpose

For nowadays construction purposes, it is necessary to define the life cycle of elements with defects. As steels 42CrMo4 and 41Cr4 are typical materials used for elements working under fatigue loading conditions, it is worth to know how they will behave after different heat treatment. Additionally, typical mechanical properties of material (hardness, tensile strength, etc.) are not defining material’s fatigue resistance. Therefore, it is worth to compare, except mechanical properties, microstructure of the samples after heat treatment as well. The paper aims to discuss these issues.

Design/methodology/approach

Samples of normalized 42CrMo4 (and 41Cr4) steel were heat treated under three different conditions. All heat treatments were designed in order to change microstructural properties of the material. Fatigue tests were carried out according to ASTM E647-15 standard using compact tension specimens. Later on, based on obtained results, coefficients C and m of Paris’ Law for all specimens were estimated. Similar procedure was performed for 41Cr4 steel after quenching and tempering in different temperatures.

Findings

The influence of heat treatment on the fatigue crack growth rates (42CrMo4, 41Cr4 steel) has been confirmed. The higher fatigue crack growth rates were observed for lower tempering temperatures.

Originality/value

This study is associated with influence of microstructural properties of the material on its’ fatigue fracture. The kinetic fatigue fracture diagrams have been constructed. For each type of material (and its heat treatment), the Paris law constants were determined.

Details

International Journal of Structural Integrity, vol. 9 no. 3
Type: Research Article
ISSN: 1757-9864

Keywords

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