Push-out tests on demountable shear connectors of steel concrete composite structures

in Structures (2019), 21

Circular Economy refers to a move from linear business models, in which products are manufactured from raw materials, used and then discarded, to circular business models where products or parts are re ... [more ▼]

Circular Economy refers to a move from linear business models, in which products are manufactured from raw materials, used and then discarded, to circular business models where products or parts are re-used, remanufactured or recycled. Structural steel is highly compatible with this concept; however, when steel-concrete composite structures are used, recycling becomes difficult and the potential for reuse is lost. In order to make steel-concrete composite structures reusable, bolted connections should replace the commonly used welded headed studs. Furthermore, the reusable parts should be designed to withstand repeated use. This paper presents a desktop study and the corresponding laboratory experiments on demountable shear connectors that facilitate recyclability and even provide the potential for reusing complete structural elements. In the Laboratory of Steel and Composite Structures of the University of Luxembourg 15 push-out tests have been carried out using different bolted connection systems suitable for multiple use. The shear connectors have been evaluated based on their shear strength, stiffness, slip capacity, ductility and ability of demounting. The investigated systems included pre-stressed and epoxy resin injection bolts, solid slabs and solid slabs in combination with profiled steel sheeting. The results showed that the tested demountable shear connections could provide higher shear resistance than conventional shear connections. The critical failure mode was the shear failure of the bolts, which is a brittle failure. There was no visible damage observed on the connected members. The application of epoxy resin in the hole clearance resulted in lower slip capacity. The outcome provides an important basis for the justification of the forthcoming enhancement and validation of numerical models of the demountable shear connections. The failure behaviour, the observed damages and the resulting ability of the elements for re-use are discussed in detail. [less ▲]

Push-out tests with modern deck sheeting and realistic transverse loading

in 12th International Conference on Steel, Space & Composite Structures (2014, May)

The push-out test as proposed in EN 1994-1-1 originally was developed for solid slabs and not for composite slabs with additional steel sheeting. It leads to a load-slip behaviour of headed shear stud ... [more ▼]

The push-out test as proposed in EN 1994-1-1 originally was developed for solid slabs and not for composite slabs with additional steel sheeting. It leads to a load-slip behaviour of headed shear stud connectors which differs from the behaviour in the real beam. In particular, the vertical forces and negative bending moments of the composite slab at its support are ignored by this setup. Within the European research project “Development of improved shear connection rules in composite beams (DISCCO)” a total of 70 push-out tests was performed to investigate a more realistic push-out test setup. The influence of the transverse loading was investigated to develop a standard push-out test when additional steel sheeting is used. The test regime used to apply transverse loads in this investigation is described and the results of 10 push-out tests with 80 mm deep steel sheeting with pairs of 19 mm diameter headed shear stud connectors are presented. The observed bearing capacities of the shear connectors were over-predicted by the empirical reduction factor given in EN 1994-1-1 and the 6 mm criterion was not always satisfied, especially when no or only low transverse loads were applied. The application of transverse loads improved the ductility of headed shear stud connectors and the bearing capacity increased by up to 41%. [less ▲]

Pushed out prematurely? Comparing objectively forced exits and subjective assessments of involuntary retirement across Europe

in Research in Social Stratification and Mobility (2015), (41), 113-128

Given the efforts in raising the statutory pension age in an aging Europe, this cross-national analysis investigates constrained retirement from a comparative perspective. Based on a conceptualization of ... [more ▼]

Given the efforts in raising the statutory pension age in an aging Europe, this cross-national analysis investigates constrained retirement from a comparative perspective. Based on a conceptualization of retirement transitions as a multi-faceted phenomenon, the study distinguishes objective (external) constraints and the subjective self-assessment of involuntary retirement. Exploiting two survey items from the fifth round of the European Social Survey (ESS Round 5, 2010/2011), we examine which workers were objectively forced to retire due to economic or health reasons as well as which workers subjectively evaluate their retirement as involuntary as they would have wished to work longer. Using multilevel modeling, the study investigates the impact of national context conditions on both the individual risk to be objectively forced to terminate work and the subjective perception of retirement as occurring too early. We analyze institutional factors such as statutory pension ages and pension generosity, but also explore the role of structural factors such as unemployment and health. At the individual level, the empirical analysis reveals that objectively forced exits and subjective involuntariness do not always overlap. Ojectively forced exits are more readily explained by socio-economic characteristics like social class and unemployment experience. At the macro level, there are considerable cross-national variations that cannot be explained by compositional factors only. Relevant predictors of international differences in constrained retriement include early retirement options, statutory pension conditions, unemployment rates, labor market regulation and life expectancy. [less ▲]

Pushing the Boundaries. New Research on the Activism of EU Supranational Institutions

in Journal of Contemporary European Research (2017), 13(2), 1007-1024

This contribution introduces the concept of ‘activism’ to the study of EU supranational institutions and their role in EU policy making and European integration. While long present in studies of the Court ... [more ▼]

This contribution introduces the concept of ‘activism’ to the study of EU supranational institutions and their role in EU policy making and European integration. While long present in studies of the Court of Justice of the EU, ‘activism’ has rarely been examined systematically in the context of analyses of other supranational institutions. This contribution offers a definition of ‘supranational institutional activism’, examines its analytical usefulness in relation to other concepts such as ‘entrepreneurship’ and through the lens of a number of political science and EU integration theories and analytical approaches. The specific analytical insights derived from the disciplines of political science, history and legal scholarship of the twelve articles of this special edition on ‘supranational institutional activism’ are also considered. While the powers and roles of EU supranational institutions have been examined in numerous studies, this article presents a concept that can contribute to a more systematic and comprehensive understanding of the contribution of these entities to EU policy making and European integration. [less ▲]

Pushing the limits of gravity field recovery from high-low satellite-to-satellite tracking –a combination of 10 years of data of the satellite pseudo-constellation CHAMP, GRACE and GOCE

Scientific Conference (2014, April)

Putting community to use in environmental policymaking: Emerging trends in Scotland and the UK

in Geography Compass (2018), e12381

Community is frequently called upon in policy to meet environmental challenges. It is increasingly recognized that the success of these environmental interventions relies on community awareness and action ... [more ▼]

Community is frequently called upon in policy to meet environmental challenges. It is increasingly recognized that the success of these environmental interventions relies on community awareness and action. But what this emphasis on community does, and what the impacts are, are often neglected, or left uncritiqued. To explore this issue, we surveyed literature from the UK across four distinct environmental domains—energy, urban greenspace, water, and land—to chart what characterizes the use of community in pursuit of environmental goals. We highlight the main conceptual commonalities across the domains by focusing on research that gives insight into the increased interest in communities in environmental policy. In summary, we posit that where community is used environmentally, it brings with it (a) a reframing of justice, (b) processes of “public making,” and (c) a rescaling of governance. [less ▲]

Putting Male and Female Bodies in Their Places: Arenas and Theatres of Educational Reform

in Burke, Catherine; Grosvenor, Ian; Haenggeli-Jenni, Béatrice (Eds.) et al Education across Europe: A Visual Conversation (2014)

Putting “Power” into Borderlands Studies: “Bringing the State Back In”

in Gilles, Peter; Koff, Harlan; Maganda, Carmen (Eds.) et al Theorizing Borders Through Analyses of Power Relationships (2013)

PVDeConv: Point-Voxel Deconvolution for Autoencoding CAD Construction in 3D

Scientific Conference (2020, October)

We propose a Point-Voxel DeConvolution (PVDeConv) mod- ule for 3D data autoencoder. To demonstrate its efficiency we learn to synthesize high-resolution point clouds of 10k points that densely describe ... [more ▼]

We propose a Point-Voxel DeConvolution (PVDeConv) mod- ule for 3D data autoencoder. To demonstrate its efficiency we learn to synthesize high-resolution point clouds of 10k points that densely describe the underlying geometry of Computer Aided Design (CAD) models. Scanning artifacts, such as pro- trusions, missing parts, smoothed edges and holes, inevitably appear in real 3D scans of fabricated CAD objects. Learning the original CAD model construction from a 3D scan requires a ground truth to be available together with the corresponding 3D scan of an object. To solve the gap, we introduce a new dedicated dataset, the CC3D, containing 50k+ pairs of CAD models and their corresponding 3D meshes. This dataset is used to learn a convolutional autoencoder for point clouds sampled from the pairs of 3D scans - CAD models. The chal- lenges of this new dataset are demonstrated in comparison with other generative point cloud sampling models trained on ShapeNet. The CC3D autoencoder is efficient with respect to memory consumption and training time as compared to state- of-the-art models for 3D data generation. [less ▲]

Pygmalion in der Schule. Wie mächtig sind Lehrererwartungen?

Article for general public (2011)