Inspection, Characterization and Structural Analysis of Timber Roof Trusses: A Case Study in Uruguay (original) (raw)
Related papers
Behaviour of traditional portuguese timber roof structures
2006
The aim of this paper is to present the results of a structural analysis of common trusses traditionally used in roof construction in Portugal. The study includes the results of a preliminary survey intending to assess the geometry, materials and on site pathologies, as well as a twodimensional linear elastic static and dynamic analysis.
International Journal of Heritage Architecture: Studies, Repairs and Maintence, 2017
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 design 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.
Analysis of an Historical Wooden Roof , the Case of San Fermo
2014
The paper concerns a part of the detailed seismic and static analysis on a XI century church located in Verona in the north of Italy. The seismic hazard of the entire country is appreciable and the effect on this structure is not negligible. After three earthquakes, and mainly after the two events happen on 2012 with epicentre in the Emilia's region, some cracks occurred on the main nave. The aim of the part of the work here presented, is mainly related to analyse and understand the real behaviour of the complex roof and its safety. The text faces two principal phases: one related to the diagnosis and site inspections with Non-Destructive tests and the other about the analytical models. The steps follow both the ISARCSAH recommendation [1] and Italian guidelines [2] for evaluation and mitigation of seismic risk to cultural heritage. The roof is a unique structure made by many struts in wood and ties in puddle iron. The structure bears the external layer of tiles and the interior ceiling with bas-reliefs in wood. In the first step about the knowledge of the structure, an accurate geometrical survey has been performed whit laser scanner and clinometers. On the other hand important Non destructive tests on humidity and resistance has been performed in order to assess the material feature and degradations. Further the dynamic identification of some elements plays a determinant role in terms of calibration. Lastly the historical information and data collected gives a wider view on the structure. During years some interventions have been done in order to strengthen the structure decreasing the internal forces. This changing of the structural configuration involves another global behaviour which changes differently in each truss and therefore it presents relative displacements throughout the wooden roof. The analysis of the entire structure is local and global and involves both linear and non linear evaluations. For each configuration during the year a model has been done in order to get the changing in stresses and stiffness.
Timber Use in Truss Structures for Roof (“Howe” Type – 8 to 18 Meters)
International Journal of Materials Engineering, 2017
The wood is a material widely used for several purposes, especially in the construction industry. There are many factors that this is due, between them the versatility and abundant availability of the material. However, the intensive use of some species might cause shortages. The lack of information about the wood behavior when it is exposed to various conditions, as well as projects not supported by regulatory rules, may imply in its inappropriate use, compromising in the safety of the structure. In this context, it was proposed the elaboration of roofing structures projects with the following characteristics: lattice type buildings "Howe" (10° slope-cement tile); span of 8, 10, 12, 14, 16 and 18 meters (geometrical proportion, in design, surrounding a 1: 3); typology of the lateral side of the building openings-relations 1:1, 2:1, 6:1 and open (coverage of small dimensions' support) preservative treatment. Then, was determined the ratio of the wood amount (m³) and the built area (in design) to woods of C20 and C30 classes, following the requirements of NBR 7190: 1997. Front of the analysis of results was evidenced that it is possible to use unconventional woods applied in triangle framework structure in big spans, obeying a well elaborated conception of project.
Seismic vulnerability and preservation of timber roof structures
Proceedings of the VI International Conference on Structural Analysis of Historic Construction, SAHC08, 2-4 July 2008, Bath, United Kingdom, 2008
Seismic vulnerability of buildings is a basic component of risk that may be reduced, when necessary, by retrofitting and strengthening interventions. A procedure for assessing the vulnerability of timber roof structures has been studied and is outlined here. The procedure is organized in two levels. A first level collects data on the various elements of the structure. This information is to point out aspects of seismic interest, giving as well a detailed picture of the general state of the structure. A second step focuses on the items that mostly control seismic vulnerability. The main factors examined are the presence of unrestrained thrusts, the connection with the supporting walls, the capability of responding in both principal directions, and the quality of carpentry joints and connections.
Reliability Assessment of Wooden Trusses of a Historical School
International Journal of GEOMATE
Records show that the National Structural Code of the Philippines (NSCP) wind load requirement increases over time. Increase wind velocity from stronger typhoon events translates to additional wind pressure. These changes pose a threat to existing historical structures such as Gabaldon schools which were designed and constructed more than a hundred years ago. The Department of Education (DepEd) continues its efforts in its conservation. Reliability assessment of wooden trusses is necessary to check if there is a need to retrofit to maintain its function and preserve its significance in the country's history. In the analysis of the roof trusses affected directly by wind load, all loads are considered as constant except for the uniformly distributed wind load. These constant loads serve as the initial stresses acting within the truss members. Uniformly distributed wind load produces additional stress on top of the initial stress. Any changes in the amount of wind load constitute proportionally to changes in the stresses of truss members. A commercially available software makes it easier to identify corresponding stresses for several amounts of wind load. Using a spreadsheet, a simple graphical model and equation are generated expressing the relationship between wind velocities against axial force, shear force and bending moment. Mechanical properties of wood establish the limits of its strength in terms of wind velocity using the graphical model and equation obtained. The result reveals the limitation of each truss member in terms of wind velocity that even ordinary people can now easily perceived and understood.
Repair and Strengthening of Traditional Timber Roof and Floor Structures
2018
In many countries, traditional buildings comprise timber roof and floor structures. Most of these structures are degraded from different causes and need to be repaired or strengthened to ensure current and/or to fulfil the requirements of a new use of the building. Current knowledge assumes the need to preserve and to protect existing timber structural systems as a cultural value, with important advantages to the overall behaviour of the building. This growing sensibility towards the preservation and maintenance of heritage buildings has led researchers to study different repair and strengthening solutions. In the case of timber roof structures, this strengthening in many cases involves the connections between the roof structural members. Joint strengthening can be done with different methods, traditional or modern ones, using well-chosen materials, simple techniques or more sophisticated ones: from simple replacement or addition of new fasteners, to the use of timber or metal eleme...
Assessment of Timber Roof Structures before and after Earthquakes
Buildings
The global objective of sustainable development has been greatly directed toward the preservation of existing structures. Therefore, condition assessment and reconstruction of existing timber structures have been gaining importance in recent times. This is particularly evident on timber roofs whose elements are exposed to degradation, either because of rheological effects or due to the direct influence of moisture and biological factors. In case of accidental events, such as an earthquake, the question of the structure’s condition is essential for the condition of the entire building. In order to prove the load-bearing capacity and serviceability of existing structures, as well as to check the need for reconstruction, it is necessary to define crucial parameters that are influencing the condition of materials, elements, and systems. Although there are many non destructive testing methods, the frequency and scope of their use, as well as the decision-making approach, have not been de...
Contribution to the knowledge of wide span wooden roofing in the area of Bologna
DOAJ (DOAJ: Directory of Open Access Journals), 2016
This study focuses on the analysis of wooden roofs in some of the most important churches of Bologna. An operational method has been set up to make the analysis repeatable and the results comparable in each different building. This paper presents the main steps of this methodology as well as the results of its application into two different case studies: St. Peter's Cathedral and the church of San Salvatore Maggiore. The aim is to improve the proposal of restoration intervention on these construction systems. This paper deals with the analysis of some examples of large wooden trusses in important churches of Bologna carried out through a survey campaign conducted with a laser scanner. This study helped to develop a wider methodology for instrumental survey, aiming to derive a series of significant information: average deviations of the structures compared to theoretical models, deformations of the elements through time, instability, material state of conservation, structural behaviour both locally and globally. All results highlighted the knowledge that the structural design of these wooden roofing is strictly related to their dimensions and assembly, the understanding of which is functional on any restoration intervention. Wooden roofing, wooden trusses, reverse engineering, point cloud, restoration intervention
Evaluation of Late Nineteenth and Early Twentieth Century Built-up Timber Trusses in Buildings
This paper presents an approach to understanding the characteristics, behavior, analysis, and repair of built-up timber trusses. Historic built-up timber trusses are generally made from dimensional lumber and usually have bolted connections and iron vertical rods. They are a product of the late 19th-century and early 20th century and are found in a range of commercial and institutional buildings. Their construction is distinct from earlier heavy timber trusses, and therefore presents a somewhat different set of evaluation criteria and repair strategies. Common problems with built-up timber trusses will be discussed, such as excessive deflection, splice failure, inappropriate repairs, and the lack of sway bracing. Examples from the author’s experience will be shown to illustrate the presentation. The examples are synthesized into a suggested structural evaluation approach, including visual cues to potential problems, modeling considerations, common errors in evaluation, and appropriate repair strategies. The approach is based on a philosophy of preservation engineering that seeks sensitive methods of strengthening and avoids unnecessary intervention.