This paper aims to quantify the evolution of damage in masonry walls under induced seismicity. A damage index equation, which is a function of the evolution of shear slippage and opening of the mortar joints, as well as of the drift ratio of masonry walls, was proposed herein. Initially, a dataset of experimental tests from in-plane quasi-static and cyclic tests on masonry walls was considered. The experimentally obtained crack patterns were investigated and their correlation with damage propagation was studied. Using a software based on the Distinct Element Method, a numerical model was developed and validated against full-scale experimental tests obtained from the literature. Wall panels representing common typologies of house façades of unreinforced masonry buildings in Northern Europe i.e. near the Groningen gas field in the Netherlands, were numerically investigated. The accumulated damage within the seismic response of the masonry walls was investigated by means of representative harmonic load excitations and an incremental dynamic analysis based on induced seismicity records from Groningen region. The ability of this index to capture different damage situations is demonstrated. The proposed methodology could also be applied to quantify damage and accumulation in masonry during strong earthquakes and aftershocks too.
Background: Clinical reasoning skills are considered to be among the key competencies a physiotherapist should possess. Yet, we know little about how physiotherapy students actually learn these skills in the workplace. A better understanding will benefit physiotherapy education.Objectives: To explore how undergraduate physiotherapy students learn clinical reasoning skills during placements.Design: A qualitative research design using focus groups and semi-structured interviews.Setting: European School of Physiotherapy, Amsterdam, the Netherlands.Participants: Twenty-two undergraduate physiotherapy students and eight clinical teachers participated in this study.Main outcome measures: Thematic analysis of focus groups and semi-structured interviews.Results: Three overarching factors appeared to influence the process of learning clinical reasoning skills: the learning environment, the clinical teacher and the student. Preclinical training failed to adequately prepare students for clinical practice, which expected them to integrate physiotherapeutic knowledge and skills into a cyclic reasoning process. Students’ basic knowledge and assessment structure therefore required further development during the placements. Clinical teachers expected a holistic, multifactorial problem-solving approach from their students. Both students and teachers considered feedback and reflection essential to clinical learning. Barriers to learning experienced by students included time constraints, limited patient exposure and patient communication.Conclusions: Undergraduate physiotherapy students develop clinical reasoning skills through comparison of and reflection on different reasoning approaches observed in professional therapists. Over time, students learn to synthesise these different approaches into their own individual approach. Physiotherapy programme developers should aim to include a wide variety of multidisciplinary settings and patient categories in their clinical placements.
In this study data-feedback in a cyclic model of data-driven teaching was used to enhance the teaching behavior of students registered in a master course for teachers. Differences between pre- and post-test measures in a simple one-group pre-test post-tests design proved to be significant with effect sizes ranging from d = 0.29 to d = 0.76. Improving teaching behavior in a time span of only six weeks on average is remarkable since earlier studies indicated that it takes over 15 years to master complex teaching skills with a ‘natural development’ of teaching skills of about 25% of a standard deviation.
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A series of tests performed on as-built and strengthened timber joist-masonry-wall specimens. The test aims at providing a complete characterization of the behaviour of the timber-joist connections under axial cyclic loading. The obtained results will be used as inputs to calibrate numerical models to simulate the connection between the cavity wall and timber joist.
Post-earthquake structural damage shows that wall collapse is one of the most common failure mechanisms in unreinforced masonry buildings. It is expected to be a critical issue also in Groningen, located in the northern part of the Netherlands, where human-induced seismicity has become an uprising problem in recent years. The majority of the existing buildings in that area are composed of unreinforced masonry; they were not designed to withstand earthquakes since the area has never been affected by tectonic earthquakes. They are characterised by vulnerable structural elements such as slender walls, large openings and cavity walls. Hence, the assessment of unreinforced masonry buildings in the Groningen province has become of high relevance. The abovementioned issue motivates engineering companies in the region to research seismic assessments of the existing structures. One of the biggest challenges is to be able to monitor structures during events in order to provide a quick post-earthquake assessment hence to obtain progressive damage on structures. The research published in the literature shows that crack detection can be a very powerful tool as an assessment technique. In order to ensure an adequate measurement, state-of-art technologies can be used for crack detection, such as special sensors or deep learning techniques for pixel-level crack segmentation on masonry surfaces. In this project, a new experiment will be run on an in-plane test setup to systematically propagate cracks to be able to detect cracks by new crack detection tools, namely digital crack sensor and vision-based crack detection. The validated product of the experiment will be tested on the monument of Fraeylemaborg.
The Ph.D. candidate will investigate the seismic response of connection details frequently used in traditional Dutch construction practice, specifically in the Groningen area. The research will focus on the experimental and numerical definition of the complete load-deflection behaviour of each considered connection; specifically, the tests will aim at identifying stiffness, strength, ductility, and dissipative behaviour of the connections. The experiments will be conducted on scaled or full-scale components that properly resemble the as-built and retrofitted as well connection details. The tests will involve monotonic and cyclic loading protocols to be able to define the load and displacement response of the connection to reversal loads, such as earthquakes, as well as the development of failure mechanisms under such loading cases. Possibly, also dynamic tests will be performed. Numerical models will be created and calibrated versus the experimental findings. Characteristic hysteretic behaviours of the examined connection types will be provided for the use of engineers and researchers.
