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Ribbed plates comprising cross-laminated timber slab, CLT, with glulam beams allow for increased span length compared to pure CLT slabs. At the moment the Eurocodes do not provide any recommendations to design a CLT plate or a ribbed plate. There are handbooks for designing ribbed plates. But are their methods the best suited? Should one use Eurocode’s gamma-method, Timoshenko, shear analogy method or maybe an FE-model? This is difficult to answer, but nevertheless important questions for a structural engineer today. This master thesis investigates some of the different design methods used today in a numerical study. The study compares analytical methods and FE-models by investigating different parameters, like span lengths 6 m, 12 m, and 18 m, or uniform load and point load. Furthermore, this thesis provides guidance and help to apply design methods for ribbed plates. The outcome of the study shows a tendency for the gamma-method and the extended gamma-method giving the lowest deflections and normal stresses in many situations. Thus, there could be a risk of underestimating these properties by using the gamma-method. On the other hand there were consistent results with the gamma-methods compared to Timoshenko- and shear analogy-method which showed more deviations from the extended gamma-method as reference. The Timoshenko-method showed anomalies with thicker CLT. In addition, an Abaqus model with 3D elements and RFEM models with 2D and 1D elements were applied. The Abaqus models gave in general higher deflections and consistent results. Concluding from this thesis the Abaqus model together with the extended gamma-method would complement each other most efficiently in the design process of ribbed plates.

The study of the influence of viscoelastic adhesives on timber-glass composite beams addresses the development of new and innovative load bearing structures. Hybrid timber-glass beams, comprising of timber flanges and a glass web, were considered. The solutions proposed in this study are based on utilizing viscoelastic adhesive bond lines to obtain optimal structural interaction between timber and glass. For hybrid timber-glass beams, numerical simulations have been developed with Abaqus, Finite element software which are verified by analytical methods according to the Eurocode 5 (EN 1995). In this study, three different bond-line geometries and three adhesives (epoxy, silicone and acrylate) have been investigated. The beams were analyzed under four-point bending. This report summarizes theoretical investigations, background studies, numerical modelling and analytical solution that have been performed. Guidance is presented which can be used for the design of timber-glass composite beams. The study has shown that the viscoelastic properties of the adhesive had no significant influence for the selected epoxy adhesive, but it can slightly affect the beam behavior with the silicone and acrylate adhesives used. From the three geometries studied, the design with an epoxy bond-line on both sides and on top of glass is regarded the best way, leading to good load-bearing structural elements where the response of the adhesive was highly influenced by its near incompressible behavior.

This thesis discusses properties arising when finite differences are implemented forsolving the two dimensional wave equation on media with various properties. Both homogeneous and heterogeneous surfaces are considered. The time derivative of the wave equation is discretised using a weighted central difference scheme, dependenton a variable parameter gamma. Stability and convergence properties are studied forsome different values of gamma. The report furthermore features an introduction to solving large sparse linear systems of equations, using so-called multigrid methods.The linear systems emerge from the finite difference discretisation scheme. Aconclusion is drawn stating that values of gamma in the unconditionally stable region provides the best computational efficiency. This holds true as the multigrid based numerical solver exhibits optimal or near optimal scaling properties.