Effects of decay on the shear properties of nailed joints parallel and perpendicular to the grain

Information on the properties of nailed joints with decayed member is necessary to evaluate the remaining structural properties of timber constructions. In this study, loading tests were conducted on nailed joints parallel and perpendicular to the grain with decayed members, and the relationship between the decrease in shear properties and the loading direction to the grain was investigated. After the loading tests, the extent of decay of the specimens was evaluated by the penetration depth of Pilodyn and the decay depth, and these were compared with the shear properties of the nailed joints. The nailed joints with decay had a low load at the initial deformation, regardless of the loading direction to the grain. The initial stiffness, yield resistance, and maximum resistance of the nailed joints parallel to the grain were negatively correlated with the Pilodyn penetration depth, and those of the nailed joints perpendicular to the grain showed no significant correlation with the Pilodyn penetration depth at the 5% level. The initial stiffness, yield resistance, and maximum resistance of the nailed joints parallel to the grain tended to decrease with increasing decay depth, and those of the nailed joints perpendicular to the grain did not exhibit this tendency. The shear properties of the nailed joints significantly decreased at small decay depths.

Analysis of a Fire in an Apartment of Timber Building Depending on the Ventilation Parameter

In modern buildings are also currently used the wooden-based construction systems. A wide range of uses the timber constructions in apartment buildings is a vision of the countries of the EU. The use of timber and the other recyclable materials in apartment buildings creates the precondition for the implementation, operation and disposal of environmental impacts of the EU 2020 Strategy. In the long term is important to transform the construction of buildings to a sustainable standard, which the application of wood in construction supports. Currently, the fire height of timber-based residential construction in most EU countries is limited to 5 storeys, provided that the timber structures are fire-protected. This paper deals with the influence of the ventilation parameter in the time and the intensity of the gas temperature during a fire in a model of an apartment building with a timber load-bearing structure. The load-bearing structure is made of CLT panels, with a mixed structural unit, i.e. with fire-resistant cladding of all load-bearing and fire-dividing structures. FDS (Fire Dynamics Simulator - PyroSim software) is used for dynamic simulations of fire in the model apartment.

Decay detection of constructional softwoods using machine olfaction

Fungal decomposition of wood severely affects the soundness of timber constructions. The diagnosis of wood decay requires direct observations or sampling by skilled experts. Wood decay often occurs in obscure spaces, including the enclosed inner spaces of walls or under the floor. In this study, we examined the ability of machine olfaction to detect odors of fungi grown on common construction softwoods to provide a novel diagnostic method for wood construction soundness. The combination of a simple device equipped with semiconductor gas sensors (gas sensor array) and multivariate analysis discriminated a fungi-related odor from control odor without instrumental analysis (e.g., gas chromatography). This method is often referred to as machine olfaction or electronic nose. We measured the odor of wood test pieces that were infected with Fomitopsis palustris or Trametes versicolor and sound test pieces using a gas sensor array. The sensor responses of the specimens showed different patterns between the inoculated and control samples. Each specimen class formed independent groups in a principal component score plot, almost regardless of wood species, fungal species, or cultivation period. This method provides a new decay diagnosis method that is cost-effective and easy to operate.

Possibilities of Useful Use of Glued Wooden Construction Residues

People have erected buildings with the use of timber structures for a long time. The uses of timber constructions are very diverse—it is used for the production of exterior wall and roof constructions, window frames and doors, and it is used for dry as well as wet premises. Scandinavian countries have extremely vast experience of using timber structures. Latvia has a rather extensive timber processing and timber structure manufacturing sector. Many companies are involved in timber processing, however, to enable even more extensive use of timber structures, environmental and technically economic requirements of contemporary building must be taken into consideration. Environmental requirements for timber structures provide certain advantages in comparison to other building materials, but technically economic requirements are very important as well. The development of manufacturing of glued constructions and research of production processes of these constructions allows one to find solutions for the reduction in the cost of timber structures, and the results of such research can ensure significant development of the use of timber structures in building, as well as reduce total construction costs. The basic objective of the study is to investigate the residual materials arising as a result of processing cross-laminated timber constructions (CLT panels), material generated as a result of high levels of construction production, and research of the opportunities to reprocess the residual materials generated as a result of laminated timber structure manufacturing into materials suitable for production of building constructions. The majority of CLT panels are manufactured using 20, 30 and 40 mm thick boards, and, during the panel manufacturing process, there are various standard thicknesses of panels, for example, 60, 80, 100, 120, 140, 160 mm, etc. Various layers are used for the creation of various thicknesses depending on the necessary technical properties. Various arrangements of the thickness of a single panel will cause different structural and physical behaviour (i.e., impact of changes in moisture, fire resistance, etc.). During the research and for the purposes of testing of CLT panels, only residues with equal types and thicknesses of lamellae were selected. Two main purposes were included in the panel testing process: (1) Comparison of technical performance of the residues of CLT panels with the classic CLT panel. Curve strength and tensile strength tests were performed in accordance with LVS EN standards (LVS EN 16351: 2016 and LVS EN 408 + A1: 2012). All the samples were prepared according to the LVS EN standards. (2) To assess the impact of two resins (melamine urea formaldehyde (MUF) and polyurethane (PU)), widely used in industry, on structural properties of recycled CLT material. Results of the research show that recycling residues of glued wooden constructions may lead to good results, and manufacturing residues of CLT panels may be successfully used in construction and for the reduction in CLT panel manufacturing costs.

The Influence of Floor Layering on Airborne Sound Insulation and Impact Noise Reduction: A Study on Cross Laminated Timber (CLT) Structures

The use of timber constructions recently increased. In particular, Cross Laminated Timber floors are often used in multi-story buildings. The development of standardization processes, product testing, design of details and joints, the speed of construction, and the advantages of eco-sustainability are the main reasons why these structures play a paramount role on the international building scene. However, for further developments, it is essential to investigate sound insulation properties, in order to meet the requirements of indoor comfort and comply with current building regulations. This work presents the results obtained by in field measurements developed using different sound sources (tapping machine, impact rubber ball, and airborne dodecahedral speaker) on Cross Laminated Timber floors, changing different sound insulation layering (suspended ceiling and floating floors). Results clearly show that the influence on noise reduction caused by different layering stimulated by diverse noise source is not constant and furthermore that no available analytical model is able to correctly predict Cross Laminated Timber floors acoustic performances.

Expert system for dimensioning reinforcement and connections of wood with steel

Ecological and sustainability values in the construction sector have become increasingly important, likewise the demand for timber constructions have increased. Simultaneously opportunities have developed to enhance the structural disadvantages of timber, leading to more economic and efficient structures. The engineering office Knippers Helbig does not only design timber structures frequently but is also a pioneer regarding the use of timber as a solid building material. This leads to the idea to develop a tool for a particular project and as a preparation tool for following project which enables the firm to evaluate advance calculations. Solutions were sought for strengthening in flexure and tension perpendicular to the grain of timber with steel as well as dimensioning connections with glued-in steel sections. With the tool, quick feasibility and variant studies for reinforcement and connection types are possible. Furthermore each dimensioning method is based on standardized calculations, so detailed verification can be performed. Da ökologische und nachhaltige Werte in den letzten Jahrzehnten auch im Bausektor von immer größerer Bedeutung werden, ist die Nachfrage nach Holzkonstruktion kontinuierlich gestiegen. Gleichzeitig oder grade deswegen entwickelten sich Möglichkeiten die strukturellen Nachteile von Holz auszubessern, was zu ökonomischeren und effizienteren Strukturen führte. Das Ingenieurbüro Knippers Helbig plant nicht nur gerne und häufig Holzkonstruktionen, sondern ist auch Vorreiter, was die Verwendung von Holz als Massivbaustoff betrifft. Daraus ergab sich die Idee, dass für ein Projekt im Speziellen und als Vorbereitung für folgende ein Tool entwickelt werden sollte, dass es ermöglicht weiterführenden Dimensionierungen zu berechnen. Dabei ging es darum Biege- und Querzugverstärkungen von Holz mit Stahl zu bemessen sowie Anschlüsse mit eingeklebten Stahlquerschnitten zu dimensionieren. Mit dem Tool dieser Masterarbeit ist es möglich zum einen schnelle Machbarkeits-, sowie Variantenstudien von Bewehrungs- oder Anschlusstypen durchzuführen, aber zum anderen liegen jedem Nachweis genormte bzw. bauaufsichtlich zugestimmten Berechnungen zugrunde, sodass Detailnachweise geführt werden können.

Expert system for dimensioning reinforcement and connections of wood with steel

Ecological and sustainability values in the construction sector have become increasingly important, likewise the demand for timber constructions have increased. Simultaneously opportunities have developed to enhance the structural disadvantages of timber, leading to more economic and efficient structures. The engineering office Knippers Helbig does not only design timber structures frequently but is also a pioneer regarding the use of timber as a solid building material. This leads to the idea to develop a tool for a particular project and as a preparation tool for following project which enables the firm to evaluate advance calculations. Solutions were sought for strengthening in flexure and tension perpendicular to the grain of timber with steel as well as dimensioning connections with glued-in steel sections. With the tool, quick feasibility and variant studies for reinforcement and connection types are possible. Furthermore each dimensioning method is based on standardized calculations, so detailed verification can be performed. Da ökologische und nachhaltige Werte in den letzten Jahrzehnten auch im Bausektor von immer größerer Bedeutung werden, ist die Nachfrage nach Holzkonstruktion kontinuierlich gestiegen. Gleichzeitig oder grade deswegen entwickelten sich Möglichkeiten die strukturellen Nachteile von Holz auszubessern, was zu ökonomischeren und effizienteren Strukturen führte. Das Ingenieurbüro Knippers Helbig plant nicht nur gerne und häufig Holzkonstruktionen, sondern ist auch Vorreiter, was die Verwendung von Holz als Massivbaustoff betrifft. Daraus ergab sich die Idee, dass für ein Projekt im Speziellen und als Vorbereitung für folgende ein Tool entwickelt werden sollte, dass es ermöglicht weiterführenden Dimensionierungen zu berechnen. Dabei ging es darum Biege- und Querzugverstärkungen von Holz mit Stahl zu bemessen sowie Anschlüsse mit eingeklebten Stahlquerschnitten zu dimensionieren. Mit dem Tool dieser Masterarbeit ist es möglich zum einen schnelle Machbarkeits-, sowie Variantenstudien von Bewehrungs- oder Anschlusstypen durchzuführen, aber zum anderen liegen jedem Nachweis genormte bzw. bauaufsichtlich zugestimmten Berechnungen zugrunde, sodass Detailnachweise geführt werden können.