Browsing by Author "Adema, A."

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    Analysis of instant and long-term performance of timber-concrete floors with boundary conditions other than simply supported
    (2022) Adema, A.; Santa María, H.; Guindos, P.
    This paper describes an analytical procedure for designing timber-concrete composites (TCC) subjected to boundary conditions other than simply supported. Currently available investigations of TCCs are mainly focused on simply supported slabs, as it is a typical configuration for timber buildings. However, in other structural applications, and remarkably for reinforced concrete buildings, the boundary conditions of the TCC slabs are not likely to be simply supported. Such distinct boundary conditions can significantly reduce the cross section height, mid-span deflection and self weight of the structure, the last one being crucial in seismic regions. The proposed procedure is derived from two simplified methods available in the literature, one general in its nature while the other being valid for simply supported beams. The short-term analytical model was compared against finite element models (FEM) and to the only experimental investigation on partially restrained TCCs available in the literature, while the long-term analytical model was compared only against FEM. At the end of the investigation, a full-scale continuous TCC beam was tested in the serviceability range, to compare with the prediction of the proposed analytical model. The model underestimated the mid-span deflection at 4.5 kN by 13%, concluding that the proposed simplified procedure is valid for boundary conditions other than simply supported. Further experimental campaigns are needed in the future to assess the versatility of the model in a wider range of boundary conditions, including short-term and long-term tests, which should enhance the applicability of TCC slabs in structures different from timber buildings and bridges.
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    Potential of continuous nail-laminated timber concrete composite slabs to cover large spans with timber
    (2024) Adema, A.; Chacón, M.F.; María, H.S.; Opazo, A.; Casanova, E.; Guindos Bretones, Pablo
    This study examines the flexural performance of six 9-m full-scale Nail-Laminated Timber Concrete (NLTC) composite slabs with continuous Boundary Conditions (BC)s. The slabs were made with lumber beams edge-joined with double nailing, end-joined with butt joints, and the reinforced concrete topping connected with a set of notches, inclined screws, or a combination of both. This slab configuration provides large-span continuous BCs, reducing their deflections in a simple and effective way. Five-point monotonic bending tests were considered for all slabs. Before full-scale slabs, compressive and tensile pull-out tests of Timber-Concrete Composite (TCC) shear connections were performed, including notches and inclined screws. Tensile pull-out tests were added to assess whether the shear connectors had dissimilar behavior under the negative bending moments expected in these unconventional BCs. Failure modes, load–mid-span deflection relation, bending stiffness, and timber-concrete slip were evaluated for all slabs. A detailed 3D micro-Finite Element (FE) model of the shear connections was built in ANSYS software, whereas a macro-FE model of NLTC slabs was made in SAP2000, demonstrating a good fit for the timber-concrete interaction and the load-carrying capacity of the composite slab under these unconventional BCs at the serviceability range, respectively. Moreover, an analytical elastic beam with the Girhammar method for continuous TCC slabs was assessed and demonstrated as more precise than the traditional -method. Predictions of the numerical and analytical (Girhammar) models for the bending stiffness at service loads up to 30% of capacity showed errors up to 10% and 57%, respectively. This study demonstrates that achieving continuous boundary conditions may be an effective way for applying timber in modern large span applications.