Experimental and numerical analyses of full-span floors and component level subassemblies for robust design of CLT floors

Tall mass timber structures are becoming increasingly prevalent and, with some now rising as tall as 81m (Abrahamsen, 2017) it is vital to consider design for structural robustness and disproportionate and progressive collapse prevention under accidental actions (Starossek & Haberland, 2012). The Eurocode 1-7 approach (European Committee for Standardization, 2006) focuses on material independent objective-based design. An inherent robustness through alternative load paths (ALPs), primarily catenary action, is targeted through introduction of vertical and horizontal ties. This is a prescriptive approach without the necessary physical basis when introducing novel construction methods

CLT Connection Behaviour Under Extreme Deformations:Influence on Structural Robustness in Large Timber Construction

Multi-storey timber construction has become increasingly popular over the past decades, largely due to its naturally low net carbon footprint. One of the important design considerations in structures of this scale is their robustness. Existing prescriptive design methods for robustness, generally developed for steel and concrete construction, cannot be directly applied to wooden structural systems without further research. Some experimental work is available on the catenary action formation in Cross-laminated timber (CLT) and Laminated Veneered Lumber (LVL), however, these tests focus on substructures and the results are difficult to generalise beyond the specific geometries and materials tested. This study focuses on developing a localised component test methodology of high repeatability which isolates the behaviour of individual elements and connections, and investigate their influence on the robustness of the structure as a whole. The experiments presented focus on two key components of CLT buildings: a continuous 5-ply CLT section and a half-lap floor joint. The solid section was tested under 3-point bending to investigate the deformations in CLT after rolling shear failure. Similarly, a 4-point bending test was performed on the half-lap joint to achieve the moment rotation curve. The force was applied until a drop of approximately 10% in the moment resistance was observed. The specimens were then transferred onto a tension testing rig. The study indicates that double span floors impede proprietary catenary formation and although the tested connections have the potential of forming catenaries, they have limited tensile and rotational capacities and may not be adequate for catenary formations in buildings above 4 storeys

Experimental investigations of connections for robustness of mass timber buildings

Recent growth in mass timber construction has raised concerns about preventing disproportionate and progressive collapse, emphasizing the need for performance-based design due to general lack of understanding the behaviour of mass timber connections under extreme load and deformations. The aim of the research presented was to expand on the current understanding of the mechanical properties of common floor panel-to-panel cross laminated timber (CLT) connections and subsequently floor systems under combined bending and tension, as typically observed under catenary action through experimental analysis. The thesis develops the methods for component-level and full-span substructure tests for CLT floors under extreme deformations that allow for distillation of the necessary parameters. The novelty of the study lays specifically in analysing the changes in these parameters due to increasing tension utilisation of the connections, which is instrumental for robustness performance analysis and has not been previously investigated. The component test developed uses a fraction of resources needed for the standard full-span testing while aiming to provide the same information about the connection behaviour, which can be used in design calculations and modelling alike. Full-span testing was performed to verify the component test results through numerical methods, as well as introducing further parameters such as continuous spanning panels and wall detailing. In total five types of CLT floor-to-floor connections were investigated, including four most commonly used currently in the industry as well as a novel tube connector

A Detector of Sleep Disorders for Using at Home, Journal of Telecommunications and Information Technology, 2014, nr 2

Obstructive sleep apnea usually requires all-night examination in a specialized clinic, under the supervision of a medical staff. Because of those requirements it is an expensive and a non-widely utilized test. Moving the examination procedure to patients’ home with automatic analysis algorithms involved will decrease the costs and make it available for larger group of patients. The developed device allows all-night recordings of the following biosignals: three channels ECG, thoracic impedance (respiration), snoring sounds and larynx vibrations. Additional information, like patient’s body position changes and electrodes’ attachment quality are estimated as well. The reproducible and high quality signals are obtained using the developed and unobtrusive device

A review of ECG-based diagnosis support systems for obstructive sleep apnea

Humans need sleep. It is important for physical and psychological recreation. During sleep our consciousness is suspended or least altered. Hence, our ability to avoid or react to disturbances is reduced. These disturbances can come from external sources or from disorders within the body. Obstructive Sleep Apnea (OSA) is such a disorder. It is caused by obstruction of the upper airways which causes periods where the breathing ceases. In many cases, periods of reduced breathing, known as hypopnea, precede OSA events. The medical background of OSA is well understood, but the traditional diagnosis is expensive, as it requires sophisticated measurements and human interpretation of potentially large amounts of physiological data. Electrocardiogram (ECG) measurements have the potential to reduce the cost of OSA diagnosis by simplifying the measurement process. On the down side, detecting OSA events based on ECG data is a complex task which requires highly skilled practitioners. Computer algorithms can help to detect the subtle signal changes which indicate the presence of a disorder. That approach has the following advantages: computers never tire, processing resources are economical and progress, in the form of better algorithms, can be easily disseminated as updates over the internet. Furthermore, Computer-Aided Diagnosis (CAD) reduces intra- and inter-observer variability. In this review, we adopt and support the position that computer based ECG signal interpretation is able to diagnose OSA with a high degree of accuracy