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This paper presents a unique study on the dynamic identification of the tallest glue-laminated timber frame building in the world using forced vibration tests (FVTs) and long-term ambient vibration tests (AVTs). Because the amount of sway in service under wind has become the governing design criterion for tall timber buildings, this paper aims to provide useful information and evaluate available tools and methods for modal identification in tall glulam timber frame buildings. First, combined operational modal analysis schemes based on the variational mode decomposition with the stochastic subspace identification and the random decrement technique were adopted to identify the modal properties from nonstationary ambient data. Then, unique full-scale forced vibration tests were conducted using two different methods to excite the building: measured electrodynamic shakers excitation and unmeasured rhythmic human-induced excitation. Finally, a finite-element (FE) model of the tall glulam frame building was developed and frequency response function (FRF)–based model updating was conducted showing that the FE model was able to predict the modal behavior of the test building. The results show that natural frequencies identified from output-only techniques are in good agreement with the FVT results. Damping ratios obtained from both AVTs and FVTs exhibited amplitude-dependent behavior with a larger variation observed in the FVT results due to larger range of response amplitudes. These results have significant consequences for the design of tall timber buildings under serviceability-level loading, where damping plays an important role. The resulting damping ranges presented in this paper can serve as a useful guideline for practicing engineers in developing their prediction models of tall timber buildings under serviceability-level loading. [ABSTRACT FROM AUTHOR]

Understanding the development of track defects, which can have a significant impact on the safety of train operations, is one of the most crucial responsibilities for railway engineers. Analysing track geometry (TG) parameters is necessary to establish an efficient track condition monitoring approach. Research has recently focused on monitoring track geometry irregularities using data collected from trains in service. Most of the previous research has focused on vertical irregularity of track, since the lateral irregularity is considerably more challenging because of the complex relative wheel-rail motion. This research work focuses on finding the relationship between the lateral acceleration and lateral irregularities from the Lateral Displacement of the Wheel relative to the Rail (LDWR). A supervised Machine Learning (ML) model is trained and tested with a dataset composed of numerical simulation on a diverse set of operational conditions. Among the tested algorithms, Random Forest regression shows the best result and polynomial regression is on the second place. Sufficient results are achieved which shows that it is possible to detect the lateral irregularities with on board computer vision sensor which can detect the LDWR. Also, a sensitivity analysis is performed which shows that lateral displacement is the most important parameter in determining the lateral irregularity from vehicle monitoring. The result of this work could be a step toward the predictive maintenance as well. [ABSTRACT FROM AUTHOR]

Shape grammars allow a designer to explore a diverse and broad design space. Especially among architects and engineers, the opportunity to evaluate numerous alternatives in the conceptual phase facilitates creativity. Since the introduction of shape grammars 50 years ago, significant research and development have been performed: new applications, combinations with optimisation and integration in digital environments, among others. Consequently, there is a need to map the existing literature to encourage further progress in the field and a lower threshold for those interested in learning more about shape grammars. This study, therefore, presents a systematic mapping of shape grammars in architecture and engineering. Mapping is performed by identifying a query of relevant keywords used in five databases, with the results forming the basis of the mapping. Each of the included articles is then screened to filter out those that do not fit the content criteria. The remaining publications are then evaluated and organised based on the attributes' application, research type, implementation, engineering and optimisation. The outcome is organised in explanatory illustrations and tables. The final discussion highlights the extensive work performed with shape grammars in the generation of two-dimensional floor plans, an increase in digital development in recent years and the need for further research. The findings indicate a gap between the state of the art and the necessary level of applicability for shape grammars to be an attractive design tool, especially for non-experts. [ABSTRACT FROM AUTHOR]

There are many uncertainties related to existing bridges that are approaching or have exceeded their original design life. Lifetime extension analysis of bridges should be based on validated numerical models that can be effectively established. This paper presents a new procedure to obtain an optimal solution from sensitivity-based model updating with respect to an improvement in the modal properties, such as the natural frequencies and mode shapes, based on realistic parameter values. The procedure combines variations in the ratios of overdetermined systems with different definitions of local parameter bounds in a structured approach using a sensitivity analysis. The feasibility of the procedure is demonstrated in an experimental case study. Model updating is performed on a full-scale steel bridge using the natural frequencies and modal assurance criterion (MAC) numbers, where the numerical model is established by considering general uncertainties and model simplifications to reduce the model complexity. From the optimal solution for the case study considered, an improvement in modal parameters is obtained with highly reliable parameter values. The proposed procedure can be applied to similar case studies, irrespective of the structure under consideration and the corresponding parameterisation to be made, to effectively obtain a validated numerical model. [ABSTRACT FROM AUTHOR]