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- Lim, Hyeong Uk, et al.
(författare)
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A surrogate model to describe uncertainties in wood floor modal frequencies
- 2019
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Ingår i: Advances in Engineering Materials, Structures and Systems : Innovations, Mechanics and Applications - Proceedings of the 7th International Conference on Structural Engineering, Mechanics and Computation, 2019 - Innovations, Mechanics and Applications - Proceedings of the 7th International Conference on Structural Engineering, Mechanics and Computation, 2019. - : CRC Press. - 9781138386969 - 9780429426506 ; , s. 121-126
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Konferensbidrag (refereegranskat)abstract
- Wooden multi-story buildings have increased their market share in Europe over the last decades, mainly due to their relatively small carbon footprint and rapid onsite construction. Compared to more conventional heavy concrete buildings, wooden buildings are more sensitive to dynamic loads at low frequencies. Moreover, the dynamic response is generally more difficult to predict. This is, for example, due to the variability in the material properties of wood. Since wood is a natural material, local variations in performance occur, even if selected members are taken from the same batch. Also, the cut and treatment of individual members have an impact, and material properties can vary with time due to changing moisture content and aging effects. In this study, we investigate the effect of variability in material properties of joists on the dynamic modal characteristics of wood floors with the help of surrogate models, constructed using polynomial chaos expansion (PCE). These surrogate models are based on computations that use a dynamic reduced-order finite-element (FE) model, calibrated to produce modal outputs consistent with floor vibration experiments. Uncertainty in modal frequencies of the wood floor systems based on the PCE surrogate models is consistent with that found using the FE model in Monte Carlo simulations, which serve to define the “truth” model. However, PCE surrogate models offer significant reduction in computation time compared to FE models, when uncertainty in dynamic behavior needs to be quantified.
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| 2. |
- Lim, Hyeong Uk, et al.
(författare)
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Uncertainty quantification of wood floor system modal frequencies resulting from variable densities in members
- 2023
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Ingår i: Structures. - 2352-0124. ; 53, s. 1425-1434
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Tidskriftsartikel (refereegranskat)abstract
- Low-frequency vibration in a multi-story wood building is of concern because failure in mitigation of such vibration may lead to occupant discomfort. Ultimately, it may cause damage to their health. Variability in material properties of the members of a wooden floor system significantly influences vibration response characteristics such as eigenfrequencies and mode shapes. In this study, we investigate the uncertainty in low-frequency characteristics of a selected wood floor system, resulting from uncertainty in the members’ material properties. We use a surrogate model developed using polynomial chaos expansion, based on a few training samples computed using a finite element model of an experimental-scale structure comprised of seven load-bearing joists of spruce. We estimate the hyperparameters needed for accurate surrogate model development and, with these, we predict probability distributions for each of the floor-system modal frequencies. Also, we perform local and global sensitivity analyses to assess how material property variation affects the modal frequencies. Results confirm the accuracy and efficiency of the developed surrogate models in prediction of the modal frequencies, resulting from uncertainty in wood material properties. The accuracy of the results is comparable to those based on more expensive Monte Carlo simulation.
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