170 research outputs found
Materiaalparameters voor constructief metselwerk
No full textopgesteld door A.Th. Vermeltfoort (hoofdstukken 1, 2, 3 en 6 en eindredactie), R. van der Pluijm (hoofdstukken 1, 2, 4, 5, 6 en eindredactie
Bond strength of masonry
No full textBond strength is not a well defined property of masonry. Normally three types of bond strength can be distinguished:
- tensile bond strength,
- shear (and torsional) bond strength,
- flexural bond strength.
In this contribution the behaviour and strength of masonry in deformation controlled uniaxial tests will be summarized (Van der Pluijm, 1992). The flexural bond strength will be related to the tensile bond strength by means of a FEM calculation.
A shear test-setup to study the behaviour and strength of bed joints will be introduced. In a test rig based on the proposed test-setup 54 defonnation controlled tests were carried out. The results of the tests will be discusse
Non-linear Behaviour of Masonry under Tension
No full textFor the micro-modelling of masonry in numerical programs that take non-linear behaviour into account, a complete description of the behaviour of masonry components has to be available. Complete means that, apart from the initial stiffness and the strength, the behaviour beyond the peak in the .. diagram is described.
This article gives an overview of deformation controlled tensile and flexural tests that have been carried out since 1990 by the author to establish the behaviour prior and beyond the maximum load under tension. All tests were carried under a monotonic increase of a deformation measured on the specimen itself.
The behaviour of units and mortar-joints under tension showed a great similarity to that of concrete. Experience in describing the non-linear behaviour of concrete under tension could be applied to the masonry components. The mode I fracture energy of units is of the same magnitude as that of concrete. The mode I fracture energy of mortar-joints is approximately one order of magnitude smaller and showed a great scatter
Paleozoic paleogeography of thenorthern Appalachians as determined from paleomagnetism and geochemistry.
No full textThe Paleozoic paleogeography of the northern Appalachians may be determined in a variety of ways. Paleomagnetism has been used to determine the paleolatitudes of volcanic and red bed bearing terranes and their relative rotations. Immobile trace-element geochemistry has been used to determine the paleotectonic affinity of volcanic rocks, and Sm-Nd model age studies have been used to characterize the provenance of sedimentary rocks. In northern Maine, the Ordovician Bluffer Pond Formation of the Munsungun Anticlinorium and the Ordovician Winterville Formation of the Pennington Mountain Anticlinorium yield paleolatitudes which place them close to the Laurentian margin (15-20\sp\circ) during the late Middle and early Late Ordovician (18\sp\circ\ \pm 9\sp\circ S and 11\sp\circ\ \pm 5\sp\circ S, respectively). Trace-element geochemical discrimination diagrams further support a back-arc basin environment for the formation of these two volcanic terranes. In north central Newfoundland red beds and volcanic rocks of the Silurian Springdale Group yield differing remanence inclinations and thus apparently differing paleolatitudes. It is concluded that the red beds exhibit anomalously shallow inclinations due perhaps to strain, while the volcanic rocks yield paleolatitudes that are in agreement with those predicted from the stable North American craton. This trend of shallow red bed inclinations is also observed in other Silurian units within Newfoundland. Thus the paleolatitudes determined from volcanic rocks are considered to be the most reliable for paleogeographic reconstructions. In the northern Appalachians, Samarium-Neodymium depleted mantle model ages from Early to Middle Paleozoic sedimentary units have been explained in terms of varying contributions from Laurentia, Avalon, Gondwana and the input of juvenile volcanic rocks during the closure of the Iapetus Ocean. These preliminary geochemical data complement other paleogeographic data and indicate the potential of this method for determining the paleogeography of the Appalachians.PhDGeologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/104190/1/9501020.pdfDescription of 9501020.pdf : Restricted to UM users only
Paleomagnetism of the Cantabria -Asturias Arc: Kinematics of arc formation and implications for final collisional adjustments within the Pangea supercontinent.
No full textThe Cantabria-Asturias Arc (CAA) of SW Europe is a highly curved Variscan belt that formed along the ancient plate boundary between Gondwana and Laurussia during the assembly of Pangea. To construct a viable kinematic and tectonic model for CAA formation, a paleomagnetic, rock magnetic, scanning electron microscopy (SEM) and structural study of two Devonian carbonate formations was undertaken to distinguish the discrete stages of deformation that the are experienced. The combination of these approaches provides a method for dating the complex deformation history experienced by the CAA and sheds new light on the mechanism of orogen-related remagnetizations and, and particularly, arc formation. The Devonian carbonates acquired three late Paleozoic remagnetizations during the Variscan orogeny of northern Spain. Rock magnetic data and SEM analyses reveal that the three late Paleozoic remagnetizations are chemical remanent magnetizations, likely facilitated by the presence of fluids. The fluids, whether externally or internally derived, were activated as a response to orogeny based on the acquisition of remagnetizations subsequent to local Variscan deformation phases. The protracted deformation history increased fluid mobility as a product of tectonic thickening, tectonically induced permeability, and/or gravity-driven flow. The paleomagnetic and structural data show that the CAA experienced true (∼100%) oroclinal bending of an originally linear belt in a two-stage tectonic history. This history represents two regional compression phases: (1) east-west compression in the Late Carboniferous and (2) north-south compression in the Permian (both in present-day coordinates). The later compression phase reflects the northward movement of Gondwana and its final collision with Laurussia. The new paleomagnetic data and this tectonic scenario argue against previously proposed syn-thrusting rotation, wrenching and indentor models for the formation of the CAA, because rotation occurred after the folding and thrusting that imparted the north-south structural grain of the belt. On a larger scale, this scenario does not support a 3500 km dextral megashear proposed by some previous paleomagnetic reconstructions of the Pangea supercontinent.PhDEarth SciencesGeologyGeophysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/126789/2/3016983.pd
Home-based palliative care for children with incurable cancer: long-term perspectives of and impact on general practitioners
No full textContext: although a large percentage of children with advanced-stage cancer die at home, remarkably little information is available regarding the experience of general practitioners (GPs) with respect to providing home-based palliative care to children with incurable cancer.Objectives: to explore the perspectives of GPs who care for children with advanced-stage cancer in a home-based setting.Methods: in this cross-sectional study, 144 GPs who provided home-based palliative care to 150 children with incurable cancer from 2001 through 2010 were invited to complete a questionnaire addressing their perspectives regarding: 1) symptom management, 2) collaboration with other health care professionals, 3) the child’s death and care after death and 4) impact of having provided palliative care, scored on distress thermometer (range 0-10).Results: a total of 112 GPs (78%) responded, and 91 GPs completed the questionnaire for 93 patients. The median interval between the child’s death and completing the questionnaire was 7 years. The most prevalent symptoms reported in the patients were fatigue (67%) and pain (61%). Difficulties with communicating with (14%), coordinating with (11%), collaborating with (11%), and contacting (2%) fellow members of the multidisciplinary treatment team were rare. Hectic (7%) and shocking (5%) situations and panic (2%) around the child’s death were rare. GPs reported feelings of sadness (61%) and/or powerlessness (43%) around the time of the patient’s death, and they rated their own distress level as relatively high during the terminal phase (median score: 6, range: 0-9.5). The majority of GPs (94%) reported that they ultimately came to terms with the child’s death.Conclusion: in general, GPs appear to be satisfied with the quality of home-based palliative care that they provide pediatric patients with incurable cancer. Communication among healthcare professionals is generally positive and is considered important. Finally, although the death of a pediatric patient has a profound impact on the GP, the majority of GPs eventually come to terms with the child’s deat
Talking about death with children with incurable cancer: perspectives from parents
No full textOBJECTIVE:To investigate the rationale and consequences associated with a parent's decision to discuss death with a child with incurable cancer.STUDY DESIGN:We present data from a larger retrospective study involving bereaved parents of a child who died of cancer. Parents were asked whether they had discussed the impending death with their child, whether they reflected on this discussion positively, their reasons for not discussing death with their child, and the manner in which the conversation regarding death occurred. The data were analyzed qualitatively using a framework approach.RESULTS:Of the 86 parents of 56 children who answered the questions regarding discussing death with their child, 55 parents of 35 children did not discuss the impending death with their child. The following themes were identified: the parents' inability to discuss the impending death; the parents' desire to protect their child; views regarding talking with children; parents' views of child characteristics; the child's unwillingness to discuss the subject; lack of opportunity to talk; and the child's disability. The parents who did discuss death with their child generally used symbolic and/or religious narratives, or they had brief, direct conversations regarding death. The majority of parents felt positive regarding their decision about whether to talk with their child about his/her impending death.CONCLUSION:Most parents in this study cited several reasons for not discussing death with their child. Our findings highlight the sensitive and complex issues surrounding these conversations, indicating that there may be a role for clinicians in supporting parents
- …
