Advanced Materials Research Vol. 778

Abstract: Our research team developed a brace type and an angle brace type of the visco-elastic damper on seismic-response controlled structure for timber structure. We performed various dependence evaluations by the materials examination of the styrene olefin-based visco-elastic body which we developed newly. We made a structural model using the performance that loading tests in timber frame. We inspected the validity of the structural model. In addition, we built a technical support system for damper setting by the time history response analysis so that a general design architect was easy to use the damper. We could express dynamics properties of visco-elastic body properties by Voigt model, and the structural model almost accorded with an examination property value. We made a structural model of the whole frame system by Kb of installation rigidity obtained from loading tests in timber frame. Because a design level almost accorded with experimental value, the validity of the frame design on seismic-response controlled structure in consideration of the dependence (distortion, frequency, temperature) of the visco-elastic body was confirmed. This visco-elastic damper on seismic-response controlled structure acquired minister authorization of Ministry of Land, Infrastructure and Transport. In addition, this damper acquired the certification of the Japan Building Disaster Prevention Association.

Abstract: The possible significance of natural building materials and their application in the existing building stock is the question of overriding importance and was explored on two levels: 1) Developing wood-based building components and optimizing manufacturing processes;2) adapted design methods, structural analysis of historical wood-based structures and respectively of contemporary structural concepts especially according to fire and earthquake. This paper illustrates the development and application of wood-based multi-layer shear wall and floor systems in existing building stocks. Several cases of mixing different material elements use for shear walls and floor constructions are presented.

Abstract: Timber is one of the most used materials in the roofs and floors of monumental constructions in Portugal. The geometry is defined by elements that occupy a limited and well defined part of the tri-dimensional space, with a clear evidence of the hierarchy of the components. Timber elements are often visible, which allows easier conservation, identification of the wood species, characterization of details and evaluation of deterioration. Complex timber structures, such as those belonging to the roofs of large monuments, are often not easy to understand in a expedite way. As the coverings of monuments as cathedrals, public buildings, mansions or villas show very complicate features, not easy to be understood during the first inspection. This is not only due to the fact that the system is very elaborate and to the large number of members but also due to continuous changes and repair past works, mostly with additional stiffening or propping. The typical result of the history of the construction is the increase in the number and the heterogeneity of the members, together with a multiplicity of connections and diversity of supports. This means that the original must be distinguished from the additions and the replacements. This complexity makes the field of conservation of historical timber structures not only a challenge but a field much in need of modern research. The objective of this paper is to present some of the Portuguese experience in this field, showing how the rehabilitation solutions can be supported by the inspection techniques and by an extensive knowledge about the constituent material from which the structure was made, both from the mechanical point of view and from the physical point of view. A number of case studies will be presented to illustrate common conservation problems, and design problems as well as the possibilities and limitations of several solutions and to discuss the suitability of several intervention methods.

Abstract: The main doors of medieval buildings or building complexes such as cathedrals or palaces are substantial structures, often weighing as much as one tonne per leaf. A survey of medieval English doors shows several distinct structural types whose different structural actions will be considered. All must develop some form of in plane action through the interaction of their components to transmit their weight back to their supports. However their complexity often allows several different modes of action, each of which will be differently affected by moisture movement within the timber, so that more than one mode of action will often need to be considered. The recent need to repair the early sixteenth century main doors of Trinity College, Cambridge involved the detailed analysis of one of these types whose structure comprised a dense grid of relatively slender muntins and ledges set within a much more substantial frame, carrying decorated boarding and mouldings on the outside face. The intention was that by understanding this structure we would be able to restore the original structural action of the door. In this case earlier interventions and permissions, and the extent of deterioration at the lower hinges, made this impossible. However, the exercise suggests an approach that might be valuable in the restoration of other doors of this type.

Abstract: Timber bridges have been built for decades all around the world. The hygroscopic material behavior of wood leads to the change of the moisture content of the wood and the dimensions depending on the climate. Therefore in regular inspections following questions arise: what happens with the wood due to the climate changes Are there major changes of the moisture content Are there differences between the natural material axes or within the cross section of the structural members To answer these questions, traffic timber bridges with big cross sections are long term monitored within a research project. The results of the moisture contents measured and a comparison between the different measuring groups and positions are presented. The analyses confirm that the moisture content in the wood follows the climate changes delayed and with smaller amplitude against the calculated equilibrium moisture content. In first steps, a different behavior of the change of the moisture content could be determined over the cross section and along the span of the member.

Abstract: Structural design, regardless of construction material, is based mainly on deterministic codes that partially take into account the real structural response under service and environmental conditions. This approach can lead to overdesigned (and expensive) structures. The differences between the designed and the real behaviors are usually due to service loads not taken into account during the design or simply to the natural degradation of materials properties with time. This is particularly true for wood, which is strongly influenced by service and environmental conditions. Structural Health Monitoring can improve the knowledge of timber structures under service conditions, provide information on material aging and follow the degradation of the overall building performance with time.A long-term monitoring control has been planned on a three-floor structure composed by wooden trusses and composite concrete-wood slabs. The structure is located in Nantes, France, and it is the new extension to the Wood Science and Technology Academy (ESB). The main purpose of the monitoring is to follow the long-term structural response from a mechanical and energetic point of view, particularly during the first few service years. Both static and dynamic behavior is being followed through strain gages and accelerometers. The measurements will be further put into relation with the environmental changes, temperature and humidity in particular, and with the operational charges with the aim to improve the comprehension of long-term performances of wooden structures under service. The goal is to propose new improved and optimized methods to make timber constructions more efficient compared to other construction materials (masonry, concrete, steel).The paper will mainly focus on the criteria used to design the architecture of the monitoring system, the parameters to measure and the sensors to install. The first analyses of the measurements will be presented at the conference to have a feedback on the performance of the installed sensors and to start to define a general protocol for the Structural Health Monitoring of such type of timber structures.

Abstract: The wooden pavilion Jeka (Echo) was built in 1843 according to the plans of the Austrian Empire garden architect Franz Schücht. Echo pavilion is the only remaining one of ten similar pavilions that were placed in the Forest-park Maksimir during the 19^th century. Since 1964 the Echo pavilion has been protected by law and declared as cultural monument of garden architecture together with the whole park Maksimir, in which it is situated. Although the pavilion was restored several times (last time in 1986) it was in very bad condition. The reconstruction and preservation of the complete pavilions wooden construction were done after a careful analysis of its recent state in 2000. Restoration of the “Echo” Pavilion was started because its construction was in poor condition and because the whole pavilion was unsafe. There was a severe decay of the lower parts of the poles, particularly those faced to the North. New poles or only the new parts of the poles were made of glued spruce core surrounded by larch heartwood. Organic solvent Tebuconazole and WOODCAP products were used in wood preservation. The restoration of the Pavilion can be seen as an attempt to extend the life time of a severely damaged cultural monument, or at least in those parts of the monument where the amendments were possible. During reconstruction a monitoring system for wood moisture content at three different positions inside the roof construction was installed. Twice a year the pavilion is being carefully visually inspected and data from data logger downloaded and correctness of the equipment verified.This example of the “Echo” Pavilion is showing that moisture monitoring systems can considerably contribute to prevent cultural heritage from decay. The installed inexpensive and simple monitoring system of early warning proved to be feasible and saved costs in the conservation of wooden cultural heritage. In times of tight budgets and increasing rates of decay moisture monitoring systems will become increasingly important.

Abstract: The Mormanno traffic Bridge, built at the end of the year 2000 in South Italy, with its glulam exposed structure spanning around 70 m, is one of the most impressive traffic timber bridges in the world. The paper illustrates the various analysis executed for the assessment of the health of the structure and for the following maintenance actions during the first twelve years of service of the Bridge (2001-2013). In the year 2004 a first visit for the assessment of the health of the timber bridge was decided. A team of experts inspected the bridge in order to check the conditions of the timber structures and register all the damages produced by weathering, fungi and insects on the structural elements. The experts found the decay still limited but recommended a maintenance action capable to stop the initial degenerative process mainly due to a moisture content higher than normal. In the year 2008 [ a new inspection team visited the bridge for the second time in order to check the effectiveness of the measures of protection adopted four years before. Non-destructive testing were used to investigate the health of the main glulam arches. The decay in the members object of the previous maintenance in general had stopped or slowed down, but in some other parts the moisture content was still higher than acceptable and more protections were added. In the following years the maintenance was completed giving the bridge the possibility to extend its service with a sufficient level of safety. The frequent inspections of the bridge structure provided useful information for the maintenance of the Mormanno bridge but also in general for the design of the durability and for the maintenance planning of exposed timber structures. Fig. 1 the Mormanno Bridge in service

Abstract: The cross-laminated timber panels (X-Lam panels) are produced for structural use in Service Classes 1 and 2 conditions, in accordance with what is established on Eurocode 5 [. Timber boards are glued together on orthogonal layers, allowing the panel to perform two important characteristics: good dimensional stability and loading in two-way directions. The influence of wood moisture content on the feasibility of cross-laminated timber is described in this paper regarding the dimensional stability of the panels when applied in high moisture locations. Several European Technical Approvals, state the low importance of the dimensional variations with moisture content of this type of panel, but some reference values can be found in other technical documents. The French Avis Technique [[[1 reference the value of 0.01mm/m for in-plane deformation (per percentage of timber moisture variation) and the TRADA Wood Information Sheet, WIS 2/3-62 [1, refers the maximum value of 0.02mm/m for the same conditions.The use of the X-Lam panels in Service Class 3 can not be used, concerning the high level of stressing in glue lines, and no producer has yet certified it for this Service Class. Moreover, the French Avis Technique doesnt allow the use of X-Lam panels in swimming-pools due to high hygrometry, even for conditions corresponding to Service Class 2.Cross laminated timber panels are widely used across Europe but are giving the first steps in Portugal at the moment. The first big project was finished in spring 2012 in Almada, comprising a building integrating a 25 meter in-door swimming-pool and a gym. In order to assess the behavior of the timber structure, due to the non-conventional using of the X-Lam panels, a monitoring program was started immediately after building construction. The results obtained are presented and discussed in this paper.

Abstract: The monitoring of timber structures exposed to natural climate fluctuations during their service life is an important topic for both their serviceability and safety. Numerical methods based on the recent advances in hygro-thermal modelling of wood can integrate the usual sensor-based monitoring techniques by reducing the maintenance costs for timber structures. In this paper, a 3D full coupled analysis based on the multi-Fickian theory with sorption hysteresis of wood is implemented in Abaqus FEM code by defining a new finite element in a user subroutine. To verify the method, the hygro-thermal behaviour of a glulam beam tested in laboratory under variable humidity within a previous research is analysed and the numerical values of moisture content are found to be in agreement with the experimental data. Furthermore, a numerical case-study of a glulam cross section under real climate variations is presented and the related results show the capability of the method to predict the moisture states in each points of the glulam member under continuously variable humidity and temperature.