Special Issue "Structural Assessment of Timber Structures"

A special issue of Buildings (ISSN 2075-5309).

Deadline for manuscript submissions: closed (30 April 2020).

Special Issue Editors

Dr. Jorge Manuel Branco
E-Mail Website
Guest Editor
Institute for Sustainability and Innovation in Structural Engineering (ISISE), University of Minho, Braga, Portugal.
Interests: timber engineering; wood and wood-based materials; timber joints; seismic design; reinforcement; sustainability
Special Issues and Collections in MDPI journals
Dr. Hélder Sousa
E-Mail Website
Guest Editor
School of Engineering, University of Minho, 4710-057 Braga, Portugal
Interests: timber engineering; wood products; reliability assessment
Special Issues and Collections in MDPI journals
Dr. Elisa Poletti
E-Mail Website
Guest Editor
University of Minho
Interests: Seismic performance and retrofitting of timber structures and traditional carpentry joints, Numerical analysis of timber structures and constitutive modeling

Special Issue Information

Dear Colleagues,

Timber structures are an important part of the architectural and cultural heritage. In fact, any action concerning the conservation, repair, retrofitting and monitoring of the built heritage cannot avoid understanding how timber structures behave, from the material level to whole structures, including their joints, to assess their present condition and to promote different strategies for interventions.

The aim of this Special Issue is to present an overview of the main steps involved in the structural assessment of timber structures, from diagnosis and assessment to the retrofitting of timber elements, joints and structures. Original contributions regarding experimental research and numerical analysis from the academic field as well as from practice are encouraged. The Special Issue will be based on the original contributions presented to the next SHATiS’19 International Conference on Structural Health Assessment of Timber Structures that will take place on 25–27 September 2019 in Guimarães, Portugal.

Dr. Jorge Manuel Branco
Dr. Hélder Sousa
Dr. Elisa Poletti
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Buildings is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Existing timber structures
  • Assessment
  • Codes and guidelines
  • Non-destructive testing
  • Repair and reinforcement
  • Monitoring
  • Case studies

Published Papers (8 papers)

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Research

Article
Assessment of the Density Loss in Anobiid Infested Pine Using X-ray Micro-Computed Tomography
Buildings 2021, 11(4), 173; https://doi.org/10.3390/buildings11040173 - 17 Apr 2021
Viewed by 444
Abstract
The present study aims at evaluating the impact of anobiid damage on pine timber elements. Anobiid attack produces a diffuse damage of the elements with a set of tunnels in random directions and sizes, thus confusing quantification. Therefore, a method was developed based [...] Read more.
The present study aims at evaluating the impact of anobiid damage on pine timber elements. Anobiid attack produces a diffuse damage of the elements with a set of tunnels in random directions and sizes, thus confusing quantification. Therefore, a method was developed based on X-ray micro-computed tomography (μ-XCT) to obtain, for naturally infested timber samples, an empirical correlation between lost material percentage (consumed by beetles) and timber apparent density (original, before degradation—OTD and residual, after degradation—RTD). The quantified density loss can then be used in further assessment of the structure. The results of the tests performed showed high correlation between original apparent density and lost material percentage (r2 = 0.60) and between residual apparent density and lost material percentage (r2 = 0.83), which confirms μ-XCT as a valuable tool to the required quantification. The loss of density results can be further applied on the definition of an assessment method for the evaluation of the residual strength of anobiids infested timber, thus contributing to reducing unnecessary replacement. The optimized procedure of the μ-XCT study for infested Maritime pine (Pinus pinaster) is presented and discussed in this article. Full article
(This article belongs to the Special Issue Structural Assessment of Timber Structures)
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Article
Mechanical Characterization of Iroko Wood Using Small Specimens
Buildings 2021, 11(3), 116; https://doi.org/10.3390/buildings11030116 - 15 Mar 2021
Viewed by 504
Abstract
Despite their favorable physical and mechanical properties for structural use, tropical woods, such as Iroko (Milicia excelsa), present knowledge gaps to be filled mainly about their mechanical characterization, which currently limit their use or result in under- or overdimensioned structural elements. [...] Read more.
Despite their favorable physical and mechanical properties for structural use, tropical woods, such as Iroko (Milicia excelsa), present knowledge gaps to be filled mainly about their mechanical characterization, which currently limit their use or result in under- or overdimensioned structural elements. Visual classification, one of the most used methods for characterizing wood, is inaccurate in the case of Iroko due to the wide variety of geographical locations in which this species can be found. In addition, mechanical characterization using test pieces with structural dimensions leads to high and impractical costs. In this context, this study aims to verify the mechanical properties of Iroko (imported from the Republic of the Congo) from small size specimens, a process that is currently standardized only for softwoods, and to verify the correlation of different properties through bending properties and ultrasound tests. Prior to the bending tests, the speed of propagation of ultrasonic waves was measured using the direct method. The results obtained show a good correlation between density and bending properties and the velocity of propagation of ultrasonic waves. Full article
(This article belongs to the Special Issue Structural Assessment of Timber Structures)
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Article
The Cartis Form for the Seismic Vulnerability Assessment of Timber Large-Span Structures
Buildings 2021, 11(2), 45; https://doi.org/10.3390/buildings11020045 - 29 Jan 2021
Viewed by 329
Abstract
Italy is located in a very active seismic zone, and many earthquakes have marked the country, some of them in the recent past. In order to take adequate measures of seismic prevention and protection, in the last decades, the Italian Civil Protection Department [...] Read more.
Italy is located in a very active seismic zone, and many earthquakes have marked the country, some of them in the recent past. In order to take adequate measures of seismic prevention and protection, in the last decades, the Italian Civil Protection Department (DPC) initiated a survey and introduced a specific form for the quick and/or post-seismic assessment of buildings. This is useful to obtain statistics on the types of structures and their vulnerability and a judgement on the damage, leading to a decision about the possibility of reuse and/or the level of retrofitting to be applied. Those activities have been developed since the beginning of 2000. This task is currently carried out by the Italian DPC-ReLUIS project research, line WP2 on the inventory of building structures, setting up the CARTIS form for any structural type, like masonry, reinforced concrete, precast concrete, steel, and timber structures, the latter being mainly related to large span buildings, extensively used in Italy. In this context, the paper presents the first draft of the CARTIS form for large span timber structures that provides a general description for typical structural schemes, through the singular points commonly considered as seismic structural vulnerabilities. Moreover, the statistics on timber large span structures based on a sample of 10 buildings is presented. Full article
(This article belongs to the Special Issue Structural Assessment of Timber Structures)
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Article
Ability to Glue Portuguese Eucalyptus Elements
Buildings 2020, 10(7), 133; https://doi.org/10.3390/buildings10070133 - 19 Jul 2020
Viewed by 1211
Abstract
Portuguese forests have changed in recent years. These changes were mainly boosted by the wildfires that affected a significant percentage of the softwood area. Eucalyptus is actually the dominant wood species in Portuguese forests. This is not a native hardwood, but is being [...] Read more.
Portuguese forests have changed in recent years. These changes were mainly boosted by the wildfires that affected a significant percentage of the softwood area. Eucalyptus is actually the dominant wood species in Portuguese forests. This is not a native hardwood, but is being planted mainly for pulp and paper production, and its availability and mechanical performance have made it very present in timber construction in the last 50 years. Within the discussion to substitute imported raw materials, mainly from softwoods, with local hardwoods for the production of engineered wood products, the study of the ability to glue eucalyptus has become a necessity. This paper presents experimental works aimed to assess the ability to glue eucalyptus elements for the production of glued laminated timber (GLT) and cross-laminated timber (CLT). Since this wood species has been known for being difficult to dry, a preliminary study on the dimensional stability under moisture content variation was performed. Then, shear strength tests were made in accordance with ASTM D143. The objective was to correlate those results with the tests performed in the following research step. In this further stage, shear strength tests of the bond line were performed following EN 14080 and EN 16351. The results obtained in all the experiments show that eucalyptus has the potential to be glued and therefore the production of GLT and/or CLT using this local undervalued wood species is potentially of high industrial interest. Full article
(This article belongs to the Special Issue Structural Assessment of Timber Structures)
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Article
Six-Steps Process of Structural Assessment of Heritage Timber Structures: Definition Based on the State of the Art
Buildings 2020, 10(6), 109; https://doi.org/10.3390/buildings10060109 - 08 Jun 2020
Cited by 4 | Viewed by 1839
Abstract
Each construction material deals with specific mechanical properties, their distribution, damage mechanisms, and degradation processes. Therefore, each material requires a particular assessment approach in order to derive a reliable description of the residual performance of the structure, correctly remove the cause of damage, [...] Read more.
Each construction material deals with specific mechanical properties, their distribution, damage mechanisms, and degradation processes. Therefore, each material requires a particular assessment approach in order to derive a reliable description of the residual performance of the structure, correctly remove the cause of damage, and proceed with the correct design of interventions. The aims of this paper are, first, the definition of a process of assessment and retrofitting of existing timber structures, both for engineered and heritage/traditional timber structures, and second, a comparison between the defined assessment process and its contents, and the content of existing guidelines, codes, and standards. In order to gain a definition of the process of assessment and retrofitting of existing timber structures, the content of scientific papers and articles was analyzed, and on this basis, an assessment process with six main steps and three milestones was developed. The content of the guidelines, codes and standards was afterwards analyzed basing on this six-steps assessment process. From a comparison among the current literature, guidelines, codes, and standards, interesting results emerged that gave us a picture of the European knowledge and interests on the assessment of existing timber structures. Not only agreement, but also discrepancies, variances, and incongruities were identified as possible topics for future research. Full article
(This article belongs to the Special Issue Structural Assessment of Timber Structures)
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Article
Distribution of Concentrated Loads in Timber-Concrete Composite Floors: Simplified Approach
Buildings 2020, 10(2), 32; https://doi.org/10.3390/buildings10020032 - 18 Feb 2020
Viewed by 1852
Abstract
Timber-concrete composite (TCC) solutions are not a novelty. They were scientifically referred to at the beginning of the 20th century and they have proven their value in recent decades. Regarding a TCC floor at the design stage, there are some assumptions, at the [...] Read more.
Timber-concrete composite (TCC) solutions are not a novelty. They were scientifically referred to at the beginning of the 20th century and they have proven their value in recent decades. Regarding a TCC floor at the design stage, there are some assumptions, at the standard level, concerning the action of concentrated loads which may be far from reality, specifically those associating the entire load to the beam over which it is applied. This naturally oversizes the beam and affects how the load is distributed transversally, affecting the TCC solution economically and mechanically. Efforts have been made to clarify how concentrated loads are distributed, in the transverse direction, on TCC floors. Real-scale floor specimens were produced and tested subjected to concentrated (point and line) loads. Moreover, a Finite Element (FE)-based model was developed and validated and the results were collected. These results show that the “loaded beam” can receive less than 50% of the concentrated point load (when concerning the inner beams of a medium-span floor, 4.00 m). Aiming at reproducing these findings on the design of these floors, a simplified equation to predict the percentage of load received by each beam as a function of the floor span, the transversal position of the beam, and the thickness of the concrete layer was suggested. Full article
(This article belongs to the Special Issue Structural Assessment of Timber Structures)
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Article
The Influence of Improved Strength Grading In Situ on Modelling Timber Strength Properties
Buildings 2020, 10(2), 30; https://doi.org/10.3390/buildings10020030 - 18 Feb 2020
Viewed by 1514
Abstract
The management and preservation of structures in our built environment are central and challenging tasks for practicing engineers. Within the CEN member states (European Committee for Standardization), the so-called Eurocodes form the basis of the design and verification of the load-bearing capacity of [...] Read more.
The management and preservation of structures in our built environment are central and challenging tasks for practicing engineers. Within the CEN member states (European Committee for Standardization), the so-called Eurocodes form the basis of the design and verification of the load-bearing capacity of structures. Current Eurocodes do not contain special recommendations for existing structures, meaning that the principles for new structures are applied. This can lead to an incorrect estimation of the load-bearing capacity within the semi-probabilistic safety concept. A central task within the investigation and evaluation of existing structures is the strength grading of the material in situ using non-/semi-destructive technical devices. Studies show the potential of the ultrasonic time-of-flight measurement in combination with visual evaluation for an improved grading. The information on the material from an improved grading technique can be used to update the material parameters as a target variable using a measured reference variable. In this contribution, test data from a partner project (spruce, pine, and oak) are analyzed, applying the stochastic grading model of Pöhlmann and Rackwitz. It can be shown that different grading techniques influence the updated distribution function of the material strength within the grade. The results depend on the timber species. Perspectives to develop updated models dependent on the knowledge available are shown and discussed. Full article
(This article belongs to the Special Issue Structural Assessment of Timber Structures)
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Article
Characterization of the Mechanical Performance in Compression Perpendicular to the Grain of Insect-Deteriorated Timber
Buildings 2020, 10(1), 14; https://doi.org/10.3390/buildings10010014 - 19 Jan 2020
Cited by 3 | Viewed by 1996
Abstract
Among biological agents, insect attacks may cause severe degradation of timber structures in the service life of buildings which leads to lower mechanical performance and, thus, maintenance problems over time. Additionally, compression perpendicular to the grain always features a weak spot with respect [...] Read more.
Among biological agents, insect attacks may cause severe degradation of timber structures in the service life of buildings which leads to lower mechanical performance and, thus, maintenance problems over time. Additionally, compression perpendicular to the grain always features a weak spot with respect to the long-term mechanical performance of timber members and joints. In the present work, the respective strength and elastic modulus were thus investigated for insect deteriorated wood. Following a standardized geometry, small samples degraded by anobiids were extracted from beams made of sweet chestnut wood (Castanea sativa Mill.) that were removed from service. Visual assessment of the external wood surfaces was then performed to identify areas infested by insects. Afterwards, destructive monotonic compression tests were carried out perpendicularly to the grain on the damaged area to determine the loss of compressive strength and elastic modulus. The experimental results showed that the loss of compressive strength and elastic modulus might be linearly correlated to the wood density loss for small samples infested by insects. Nonetheless, future work should focus on determining accurately the density loss in the insect-deteriorated part through non- or semi-destructive tests, in order to establish stronger relationships with the mechanical properties loss investigated. Full article
(This article belongs to the Special Issue Structural Assessment of Timber Structures)
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