Strength parameters for fasteners determined in accordance with the methods prescribed for the European CE-marking leads to quite different values for seemingly similar products from different manufactures. The results are hardly repeatable, to some extent due to difficulties in selecting representative on engineered wood products...
Timber provides attractive earthquake performance characteristics for regions of high seismic risk, particularly its high strength-to-weight ratio; however, current timber structural systems are associated with relatively low design force reduction factors due to their low inherent ductility when compared to high-performance concrete and steel...
The advantages of the two different building construction materials, timber and concrete, can be used effectively in adhesive-bonded timber-concrete composite constructions. The long-term behavior was investigated experimentally on small-scale...
The current research investigated the delamination process of adhesively bonded hardwood (European beech) elements subject to changing climatic conditions. For the study of the long-term fracture mechanical behavior of gluedlaminated components under varying moisture content, the role of moisture development, time- and moisture-dependent responses are absolutely crucial. For this purpose, a 3D orthotropic hygro-elastic, plastic, visco-elastic, mechano-sorptive wood constitutive model with moisture-dependent material constants was presented in this work. Such a comprehensive material model is capable to capture the true historydependent stress states and deformations which are essential to achieve reliable design of timber structures. Besides the solid wood substrates, the adhesive material also influences the interface performance considerably. Hence, to gain further insight into the stresses and deformations generated in the bond-line, a general hygro-elastic, plastic, visco-elastic creep material model for adhesive was introduced as well. The associated numerical algorithms developed on the basis of additive decomposition of the total strain were formulated and implemented within the Abaqus Finite Element (FE) package. Functionality and performance of the proposed approach were evaluated by performing multiple verification simulations of wood components, under different combinations of mechanical loading and moisture variation. Moreover, the generality and efficiency of the presented approach was further demonstrated by conducting an application example of a hybrid wood element.
Project contacts are Frederico França at Mississippi State University and Robert J. Ross at the Forest Products Laboratory
Summary
With the rapid development of CLT manufacturing capacity around the world and the increasing architectural acceptance and adoption, there is a current and pressing need regarding adhesive bond quality assurance in manufacturing. As with other engineered glued composites, adhesive bondline performance is critically important. Bondline assessment requires technology in the form of sensors, ultrasonics, load cells, or other means of reliable machine evaluation.
The objectives of this cooperative study are to develop quality assurance procedures for monitoring the quality of mass timber and CLT during and after manufacturing and to develop assessment techniques for CLT panels in-service.
Airborne sound insulation performance of wall assemblies is a critical aspect which is directly associated with the comfort level of the occupants, which in turn affects the market acceptance. In single-family and low-rise residential buildings, the partition walls, whether loadbearing or non-loadbearing, are commonly framed with studs of solid sawn lumber of 2x4, 2x6, and 2x8. In commercial buildings and multi-storey residential buildings, the partition walls are commonly framed using light-gauge steel studs.
The shortcomings of solid sawn lumber studs form the motivation for this project to develop wood studs that would address these shortcomings to promote greater wood use in partition walls.
The conceptual design and fabrication work and the preliminary test results have shown that are partition-wall stud made out of composite wood material could have the same or better airborne sound insulation performance as compared to the 25 gauge steel stud. The concept is promising, with a manufacturing process and fabrication that would work and be practical.
For wood floor systems, their vibration performance is significantly dependent on the conditions of their supports, specifically the rigidity of the support. Detrimental effects could result if the floor supports do not have sufficient rigidity. This is special ture for floor supporting beams. The problem of vibrating floor due to flexible supporting beams can be solved through proper design of the supporting beams. However, there is currently no criterion set for the minimum requirement for floor supporting beam stiffness to ensure the beam is rigid enough. Designers’ current practice is to use the uniform load deflection criteria specified in the code for designing the supporting beams. This criterion is based on certain ratios of the floor span (e.g. L/360, L/480 etc.). The disadvantage of this approach is that it allows larger deflections for longer-span beams than for shorter beams. This means that engineers have to use their experience and judgement to select a proper ratio, particularly for the long-span beams. Therefore, a better vibration-controlled design criterion for supporting beams is needed.
It is recommended to further verify the ruggedness of the proposed stiffness criterion for floor supporting beams using new field supporting beam data whenever they become available.
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