Historic Timber Roof Research Articles

Automatic completion of geometric models from point clouds for analyzing historic timber roof structures

Automatic completion of geometric models from point clouds for analyzing historic timber roof structures

Historic timber roof structure vulnerability assessment procedures – Critical analysis and comparison

Historic timber roof structures in Europe are examples of some of the continent's most intricate and ingenious structural solutions. They were built in close connection with their context and the heritage building to which they belonged. In addition, they were built according to the knowledge of the craftsmen.Considering the value of historical construction techniques, in recent years, many researchers have attempted to develop complex methods that could be used to accurately evaluate them and determine both their value and vulnerability to ultimately develop suitable intervention solutions. However, existing historic roof structure assessment methodologies mainly analyse their structural aspects and state of conservation. Considering this, in recent years, a new assessment procedure was developed based on desk and on-site surveys. It approaches historic timber roof structures in a multi-, inter-, and transdisciplinary manner, highlighting their complexity while bringing forward more information about their historical and cultural value.Therefore, to bring forward the originality of the procedure, a series of roof structures from Timisoara, Romania, were evaluated using the developed procedure and their value and vulnerability identified. The results were subsequently compared with those obtained using two other score-based procedures, which approach roof structures mainly based on their structural characteristics and state of conservation.The paper shows that despite the apparent differences between the considered procedures, from assessed features to the interpretation of the results, the outcomes are pretty similar and that each one of them can be used depending on the primary purpose of the assessment.

Reinforcement methodologies of timber elements in historic timber roofs

This paper aims to present a comprehensive review of the reinforcement of historic timber roofs, focusing on their main characteristics, advantages, and disadvantages, which would help professionals select and define the design of reinforcement solutions. Cultural heritage issues are taken into consideration. Reinforcement can be done via different methods – traditional and modern – using simple or sophisticated techniques. An overview of the main materials and the techniques used for selected case studies are presented, illustrating how various reinforcement methods are implemented in practice.

Historic timber roofs, a knowledge-based approach to strengthening: the case study of a Renaissance palace in Ferrara

Knowledge is essential to preserve timber roof structures for their historical and architectural value, since it allows to fully understand their cultural significance and actual structural behavior, thus planning specific strengthening interventions. This paper presents the case study of Palazzo Costabili in Ferrara, Italy, to propose a method to plan architectural strengthening intervention on historical timber roof structures based on a detailed knowledge of the structures’ features and state. The palace object of this study is characterized by historical timber structures, an expression of traditional local building techniques, which were partially damaged in the 2012 earthquake. Therefore, an in-depth and careful study of the structure was carried out to identify specific parts that needed to be reinforced. A strengthening of the roof structure was thus designed considering the performances of the timber components and their historical-cultural value. More specifically, the timber roof was first assessed to identify the main wood species, the constructive types, and their related vulnerabilities. At the same time, the parts that showed consistent signs of structural stress were later evaluated by specialists using visual and instrumental analysis. Finally, data collected were critically analyzed to better plan the strengthening intervention, considering both the stress state of the single components and their specific weaknesses, in full compliance with preservation criteria and needs.

Learning from tradition: a case study of the diagnosis, dendrochronological dating, and intervention on a 16th-century timber roof structure in the western Italian Alps

The paper presents a significant case study: the Church of San Giovanni Battista in Salbertrand dates back to the 16th century and constitutes one of the most interesting examples of religious architecture in the Susa Valley of the western Italian Alps. Its historic timber roof structure was once at risk of demolition, but in 2000 finally became the object of necessary preservation and reinforcement works. Here, the interdisciplinary studies carried out for the diagnosis and assessment of the state of conservation are presented, starting with the identification of the wood species used, the geometrical survey, the visual and NDT diagnosis of the timber elements, and the structural evaluation. A special section is dedicated to the dendrochronological analysis, with a comparison of different case studies regarding larch roof structures of other historic architectures located in the northwest of Italy. The tree-ring sequences obtained from the buildings presented have also been used to define a larch chronology of the Susa Valley in Piedmont. Following the first assessment phase, a second phase involved defining the restoration and reinforcement interventions. The reinterpretation of historic craftsmanship rules and traditions, which already contemplated the use of steel devices, attempted to offer alternative design solutions. This reinterpretation constituted the basis of the reinforcement interventions carried out in Salbertrand in the early 2000s. This paper highlights the importance of learning from historical treatises, showing how, even in modern reinforcement interventions, the application of traditional carpentry rules can achieve the aims of preservation and structural efficiency with overall cost-effectiveness and durability, resulting in a favorable balance between tradition and innovation.

Remarkable historic timber roofs. Knowledge and conservation practice Part 2 - Investigation, analysis, and interventions

Remarkable historic timber roofs. Knowledge and conservation practice Part 2 - Investigation, analysis, and interventions

A novel approach for modelling a historic timber roof

ABSTRACT Værnes church is one of the oldest mediaeval stone churches with the original wooden roof in Norway. The roof is made of several crossed layers of wooden boards connected with a large number of wooden dowels and has stood for centuries, but there are visible deformations in the lower parts of the structure. In this work, finite element models of the roof are presented in an attempt to characterise the behaviour of the wooden connections in the diaphragm. Two main scenarios are discussed: a first scenario that takes into consideration only the frame with line loads, considering the wooden boards merely as loads and a second scenario where the wooden boards are considered collaborating planks that influence the behaviour of the structure. As result of the work, it is possible to state that the wooden planks provide a stiffening effect, distributing the load on the gable walls. .

Historic timber roofs in Belgium: overview of materials and structures (1150-1960)

Belgium has a remarkable heritage of historic timber roofs that can be traced back to the 12th century. This contribution provides a review of 60 years of research on Belgian timber roofs and outlines their developments from 1150 to 1960. The focus is firstly put on wood resources, a crucial parameter for roof construction in a scarcely forested landscape. Then, the evolution of structural concepts over 800 years is discussed based on illustrations of remarkable roofs. Moreover, this broad overview raises several questions that open up new prospects for future investigations.

Remarkable historic timber roofs. Knowledge and conservation practicePart 1 - Construction history and survey of historic timber roofs

Remarkable historic timber roofs. Knowledge and conservation practicePart 1 - Construction history and survey of historic timber roofs

Moisture content changing of a historic roof structure in terms of climate effects

Abstract Timber is a widely used material in construction. The moisture content has a significant impact on the mechanical and physical properties of it. This paper studies how the moisture content values are directly connected to the climate conditions, especially temperature and relative humidity, by measuring these factors for a non-renovated historical timber roof for a one-year period, combined with meteorological data for Pécs since 1901. The fluctuation in moisture content values created instability in the water content of the structural elements due to absorption and release of water in order to reach the equivalent moisture content point. This process led to continuous volume increase-decrease of the timber, thus to formation of cracks, discoloration and harmful fungi development.

Historic Timber Roof Structure Reconstruction through Automated Analysis of Point Clouds.

We present a set of methods to improve the automation of the parametric 3D modeling of historic roof structures using terrestrial laser scanning (TLS) point clouds. The final product of the TLS point clouds consist of 3D representation of all objects, which were visible during the scanning, including structural elements, wooden walking ways and rails, roof cover and the ground; thus, a new method was applied to detect and exclude the roof cover points. On the interior roof points, a region-growing segmentation-based beam side face searching approach was extended with an additional method that splits complex segments into linear sub-segments. The presented workflow was conducted on an entire historic roof structure. The main target is to increase the automation of the modeling in the context of completeness. The number of manually counted beams served as reference to define a completeness ratio for results of automatically modeling beams. The analysis shows that this approach could increase the quantitative completeness of the full automatically generated 3D model of the roof structure from 29% to 63%.

The Impact of Timber Roof Framework Over Historical Masonry Structures

Romania is a European country, crossed by Carpathian Mountains and Danube River, with two important seismic zones. First and most dangerous one is Vrancea zone, near the capital of the country, Bucharest. The second most important seismic area is Banat, characterized by shallow earthquakes and a peak ground acceleration of 0.2. The most important city located in the second seismic zone is Timisoara, a city known in the past as Castrum Regium Themes which dates from 1212. Timisoara has been influenced by many cultures, such as Ottoman, Hungarian and Austrian, influence that can be seen also through the architecture of the city, especially in the historical zones, characterized by 1-4 storey masonry buildings with very complex and elegant timber roof framework. The dominant architectural styles are Secession and Art Nouveau. During the life period of the historical buildings, there were registered few seismic events, but the actual state of the buildings is a good one, with small problems caused by lack of proper maintenance or time-passing over construction materials. The global good behaviour of the buildings from the historical areas of Timisoara, despite the small seismic site-source distance and epicentral depth, remained a subject of interest for years. This article studies if and how the existence of such a complex timber roof framework influence the seismic behaviour of the masonry structure and entire building. The study was made based on non-linear analysis obtained with Tremuri software, determining the seismic vulnerability of the case study buildings with and without considering the timber roof. In the context of Timisoara European Capital of Culture 2021, the assessment of the seismic vulnerability of the most important buildings of the city is highly relevant. In the same time, considering the actual trend of replacing the historical timber roof framework with more modern structures, there is mandatory to understand how this specific timber structure contributes to the structural integrity of the historical masonry buildings.

Structural and health assessment of historic timber roofs from the Convent of Christ in Tomar

Before coming up with any important decision of intervention in the restoration process of existing buildings, the assessment of the conservation state is required as regards heritage timber structures and especially for those that suffered a lack of maintenance in their service life. In that context, three timber roof structures from the Convent of Christ in Tomar, Portugal, were selected and investigated. To this end, a research methodology was introduced and applied to these case studies into four main steps: (1) visual inspection; (2) non-destructive wood diagnosis; (3) structural safety evaluation; (4) prevention and intervention measures. For the visual inspection, every element and joint constituting the roof structures received scrutiny through assessing the wood species, the different construction stages and, last but not least, their respective geometry. As regards the encountered pathologies, structural disorders (e.g. accidental failure, serviceability defects…) and wood deteriorations due to biological agents (e.g. wood-destroying fungi or insects), which ineluctably leads to a likely decrease of the mechanical performances of the roof structure, were reported. To estimate the residual element cross section and elastic modulus, wood diagnosis was carried out using three relevant non-destructive tests: (1) ultrasonic pulse velocity; (2) drilling resistance; (3) impact penetration. From the collected data, the three timber roof structures were modelled on a commercial software to check their safety and integrity. Based on those outcomes, some prevention and intervention measures haves been lastly proposed case by case.

Methodology of Restoration of Historical Timber Roof Frames. Application to Traditional Spanish Structural Carpentry

ABSTRACTThis article presents the multidisciplinary methodology employed in the restoration of a 17th-century timber roof frame in Spain. This detailed methodology furthers contributions of previous researchers and could be applied to any restoration work of patrimonial architecture.Our interest focuses on two main aspects: the importance of the knowledge of construction techniques of the time that the work in question was built and the necessary continuous interrelation between the different aspects involved in the process.The historical survey enjoys a greater scope than the mere description of the historical-constructive evolution. The collective consideration of all the aspects involved allows us to perform inspections properly, to detect the critical points of the system and even, as in this case, to define the criteria and procedure of intervention.For clarification purposes the characteristics of the rafter and collar-beam system used in this building and its references in carpentry treatises are also described.

A preventive conservation approach for historical timber roof structures

PurposeThe purpose of this paper is to illustrate the assets of a preventive conservation approach for historical timber roof structures, as a means to improve the quality and durability of maintenance and repair interventions.Design/methodology/approachThe advantages of a preventive approach for historical structures were identified based on two analyses: a study of the structures’ behaviour and an investigation of existing approaches in current practice. The two main identified advantages of the approach, the cyclic process-approach and the potential of knowledge enhancement, were hereafter conceptually implemented in existing approaches.FindingsCurrent practices focus on single curative interventions, and monitoring is often considered redundant. The importance of monitoring and knowledge enhancement is demonstrated based on the theory of complex adaptive systems (CAS). A preventive conservation approach for historic timber roof structures allows integrating these insights.Research limitations/implicationsThe analysis of current practice is a sample survey, and the proposed preventive conservation approach is presented at a conceptual level. Future research foresees a more elaborated study of current practice and detailed validation of the developed approach.Originality/valueThree new contributions to the existing research on preventive conservation are: arguments for the implementation of a preventive approach, based on an analysis of the structures’ behaviour; the identification of limitations of current approaches that can be tackled in a preventive conservation approach; and the integration of the existing international guidelines and the principles of preventive conservation into a conceptual approach for the monitoring and management of these structures. Furthermore, the research paper demonstrates how timber structures can be understood as CAS, which is a novel viewpoint.

Conservation of historic timber roof structures of Italian architectural heritage: diagnosis, assessment, and intervention

ABSTRACTIn the context of our architectural heritage, timber structures represent an important sector in terms of historical relevance, architectural technology, and construction materials. In the past, these structures did not receive much attention in terms of conservation: they were frequently subject to inappropriate interventions or demolitions. Roof structures constitute an integral part of the architectural complex in which they are located and should be treated with the same attention and respect due to their historical significance. The conservation process of these structures has found a proper role in the preservation project partly as a result of technological innovations and regulations of the sector of wooden artefacts belonging to cultural heritage.This article presents multi-disciplinary research projects for the conservation and rehabilitation of historic timber roof structures carried out over a period of 30 years. The study involved ten roofs mainly belonging to the architectural heritage of northern Italy, of which five of them are included on the UNESCO World Heritage List.

PARAMETRIC MODELLING OF AS-BUILT BEAM FRAMED STRUCTURE IN BIM ENVIRONMENT

Abstract. A complete documentation and conservation of a historic timber roof requires the integration of geometry modelling, attributional and dynamic information management and results of structural analysis. Recently developed as-built Building Information Modelling (BIM) technique has the potential to provide a uniform platform, which provides possibility to integrate the traditional geometry modelling, parametric elements management and structural analysis together. The main objective of the project presented in this paper is to develop a parametric modelling tool for a timber roof structure whose elements are leaning and crossing beam frame. Since Autodesk Revit, as the typical BIM software, provides the platform for parametric modelling and information management, an API plugin, able to automatically create the parametric beam elements and link them together with strict relationship, was developed. The plugin under development is introduced in the paper, which can obtain the parametric beam model via Autodesk Revit API from total station points and terrestrial laser scanning data. The results show the potential of automatizing the parametric modelling by interactive API development in BIM environment. It also integrates the separate data processing and different platforms into the uniform Revit software.

Non-destructive testing of the historic timber roof structures of the national museum in stockholm, sweden

The National Museum in Stockholm is Sweden’s leading museum of art and design. Behind the now closed doors of the National Museum and its construction coverings a renovation project is taking place, which began in 2014 and will be completed in 2018. The renovation project will create a modern museum, a brighter atmosphere for the arts and for its visitors. Part of the renovation project was to de-sign and upgrade the timber roof structure for new loads according to Eurocode 5. As the roof structure was originally built in 1860, it was important to evaluate the condition and mechanical properties of the original load-bearing timber members. The roof structure, which is of main interest, comprises roof trusses and lantern structures.The main aim of the project regarding the timber roof structure in the National Museum was a safety verification in both the ultimate state (ULS) and the serviceability limit state (SLS). The preliminary capacity calculations for the roof structure showed that the roof members were under the new load conditions (with increased loads due to security and environmental requirements) utilized above 100%. Therefore, an investigation into the properties of the old timber members and connections was of vital importance. The need for non-destructive testing (NDT) of structural timber is well known under the name of strength grading and the concept has been used for many years to classify timber with respect to mechanical performance. The stress wave technique used in the project was based on commercial instruments such as FAKOPP®. The timber quality investigation for the attic roof structures showed that the material was generally in very good condition. As a result, according to SS-EN 338-2009, the timber strength could be assigned strength class C27–C30. Based on the results of the investigation, further design of strengthening works and refurbishment of the roof structure were being undertaken

A database model for the analysis and assessment of historic timber roof structures

Visual inspection assisted by well-structured forms allows experts to collect homogeneous data in order to report typical damage/vulnerabilities of structures. This is the basis for deriving vulnerability factors to predict failure mechanisms and identify urgent interventions. A database model with an associated structured form for the assessment of historic timber roof structures has been developed during a two-week Short Term Scientific Mission (STSM) in May 2015 at CNR IVALSA Institute in San Michele All’Adige (Italy). The aim is to assist during inspection in recording all the necessary information and later in analysing data from several inspections, allowing to identify typical damage and its causes. The database model, starting from the work of COST Action FP 1101 and further developed and digitalised during the STSM, has been initially populated with data previously collected by the University of Strathclyde through visual assessment of 29 historic timber roofs in Scotland.

Structural Analysis of Gothic Roof Trusses in View of their Conservation. Case Study of St. Paul's Cathedral, Liège (Belgium)

This study focuses on the structural behaviour of gothic roof structures. Starting from the case study of St. Paul’s Cathedral, Liège (Belgium), the aim of the research was to identify and understand the reasons and possible consequences of past and future structural distortions for the conservation of this historical timber roof structure.The wooden structure of St. Paul’s Cathedral is an interesting example of a 13th and 14th century timber-framed roof. The entire structure has mainly preserved its authentic parts even if transformations and reinforcements were made until mid-20th century. Today, these interventions must be evaluated from a critical point of view in order to preserve the authenticity of the structure. Two interventions have been studied more particularly. Firstly, the effects of an important neo-gothic restoration made in the 19th century and secondly, the consolidations of the frames, made after the bombings of WWII. Preliminary studies have proved that these interventions were poorly documented. As often in the past, hidden under the roofs, historic wooden structures were forgotten. However, we found some very interesting texts which have been confronted to an architectural analysis of the building and a study of the pathologies. These surveys have been used to undertake a structural analysis of the gothic roof structure in order to better understand and explain distortions and reinforcements of the frames.Due to biological deterioration, hypotheses on the resistance of wood have been implemented in the 3D models. We paid special attention to the nodes connections in order to evaluate their resistances to shear forces. Our models highlight critical areas which correspond to visible deformations and breakings produced after a bombing in 1945. The influence of the neo-gothic masonry, which encloses the wooden structure, has been also discussed. Due to a high humidity level, important structural degradations are visible on the base of the frames. Therefore, we also focused our attention on the evaluation of resistance of the principal-rafter, directly in contact with the masonry.