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See detailNumerical study on design rules for minimum degree of shear connection in propped steel-concrete composite beams
Vigneri, Valentino; Odenbreit, Christoph UL; Romero, Alfredo UL

in Engineering Structures (2021), 241

This manuscript presents a numerical study on simply supported propped composite beams with ductile shear connectors subjected to uniformly distributed load. The aim is to assess the performance of the ... [more ▼]

This manuscript presents a numerical study on simply supported propped composite beams with ductile shear connectors subjected to uniformly distributed load. The aim is to assess the performance of the revised rules for the minimum degree of shear connection (CEN/TC250/SC4.T3) with respect to the occurring slip. First, a non-linear 3D finite element model was developed through the software ABAQUS 2017 and validated against analytical values of the elastic stiffness and plastic bending resistance. Then, 91 configurations were analysed for different degrees of shear connection η=0.2,0.4…1.0. The span ranges from 6 to 25 m while the geometrical and mechanical properties varied within their typical field of applicability. According to both current and revised rules, 16 configurations with relatively deep beam and “weak” concrete slab exhibited allowable slip values smax significantly higher than 6 m. Therefore, the authors proposed a reduction of the maximum degree of utilization to these special cases. If the proposed reduction is included in the revised rules, none of the considered cases exhibit a slip smax higher than 8 mm while few cases have smax between 6 and 8 mm. For the ease of use, a design proposal is reformulated as a conditional reduction of the plastic bending resistance of the composite section. [less ▲]

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See detailEffective resistance of demountable shear connectors
Kozma, Andras UL; Yang, Jie UL; Odenbreit, Christoph UL

in Proceedings of ICMS (2021, June 16)

Steel-concrete composite construction is structurally efficient but is impossible to dismount where the floor slab is permanently connected to the steel beams through traditional welded studs. This ... [more ▼]

Steel-concrete composite construction is structurally efficient but is impossible to dismount where the floor slab is permanently connected to the steel beams through traditional welded studs. This contradicts the reuse and reduce aspects of the circular economy concept which has recently been introduced to the construction industry. Within the RFCS REDUCE project, several solutions have been proposed. Demountability of the composite beams using the proposed new shear connectors has been successfully demonstrated by push-out tests and full-scale beam tests. Both experiments and numerical simulations showed that the composite beams can develop plasticity even the demountable shear connectors in solid concrete slabs failed in a brittle way. To extend the scope of Eurocode 4 and avoid uneconomic elastic design, effective shear resistance of the demountable shear connectors was defined by using a newly developed algorithm, for the calculation of the plastic moment capacity of composite sections with partial shear connection. [less ▲]

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See detailNumerical study on the revised rules for minimum degree of shear connection in propped and unpropped steel-concrete composite beams
Odenbreit, Christoph UL; Vigneri, Valentino UL

in Proceedings of ICMS (2021, June 16)

The work presents a numerical study that focuses on steel-concrete composite beams using ductile headed stud shear connectors. The objective is to check the suitability of the proposed revised EN 1994-1-1 ... [more ▼]

The work presents a numerical study that focuses on steel-concrete composite beams using ductile headed stud shear connectors. The objective is to check the suitability of the proposed revised EN 1994-1-1 rules for the minimum degree of shear connection. Therefore, a non-linear 3D finite element model of simply supported composite beams was developed and validated against the analytical values of the plastic bending design resistance. The parametric study consists of 10 configurations where the relative slip at slab-beam interface was carefully investigated at different degrees of shear connection and propping conditions. Specifically, the slip at the minimum degree of shear connection shall not exceed the limit of 6 mm defined as the characteristic slip of ductile connector according to EN 1994-1-1. The results showed that the revised rules for unpropped beams delivers conservative results whereas one case with propped conditions exhibit a maximum slip significantly higher than 6 mm. [less ▲]

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See detailResistance of a new type of flat shear connectors dedicated to composite columns
Chrzanowski, Maciej Piotr UL; Odenbreit, Christoph UL; Obiala, Renata UL et al

in Proceedings of ICMS (2021, June 16)

The current practice to assure composite action foresees the usage of headed studs. This type of mechanical shear connectors was developed for composite beams and only adopted for the column’s usage ... [more ▼]

The current practice to assure composite action foresees the usage of headed studs. This type of mechanical shear connectors was developed for composite beams and only adopted for the column’s usage. Application in composite columns could lead to a reduced economy, especially for heavy composite columns used in high-rise buildings. A new type of flat shear connectors was developed and characterized that allows for fully automatic application process. This secures an increased safety of the whole structure, improved performance, optimized cross-section, reduced manufacturing time and costs. The presented paper gives a short description about the development process and focuses on the proposed analytical model describing the resistance of flat shear connectors. The developed analytical model comprises the complex stress state, which is present in the highly confined concrete directly under the connectors. The assumptions and theoretical models were confirmed in complex non-linear FE simulations performed in the Abaqus software. [less ▲]

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See detailTechnical Report LA19.E Rev. B. Headed studs in profiled steel sheeting transverse to the beam. Investigations on design resistance of headed stud shear connectors on the basis of the Final Draft of SC4.PT3 (April 2018)
Odenbreit, Christoph UL; Vigneri, Valentino

Report (2021)

The unsafety of current design rules for novel types of open-trough deck geometries for the resistance of headed studs in profiled steel sheeting is well known [1] and it was the main reason behind the ... [more ▼]

The unsafety of current design rules for novel types of open-trough deck geometries for the resistance of headed studs in profiled steel sheeting is well known [1] and it was the main reason behind the nomination of CEN/TC250/SC4- Task SC4.T3: “Revised rules for shear connection in the presence of modern forms of profiled sheeting”. During the RFCS research project “DISCCO” (RFCS-CT-2012-00030) [1], a mechanical model was developed on the basis of a large literature study and previous studies [2, 3, 4, 5, 6] while the corresponding design equations were presented by CEN/TC250/SC4.PT3 and further enhanced during the Research Project “ShearCON” of University of Luxembourg. In order to let the current rules of EN 1994-1-1 6.6 (Eq.(2) and (3)) as unchanged as possible, the limits of its suitable field of applicability (Database B1) was investigated thoroughly by means of the statistical procedure of EN 1990 D.8 [7]. The newly proposed equations (Eq. (7) and (8)) apply only to the cases outside these limits (Database B2). In this way, the proposed solution is able to restore the level of safety to its initial value, so that the partial safety factor for the shear connection ϒV=1.25 is adequate. Conversely, the current situation (without including the new design equations) would need a much higher partial safety factor as shown below. [less ▲]

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See detailHeaded studs in profiled steel sheeting transverse to the beam. Investigations on design resistance of headed stud shear connectors on the basis of the Final Draft of SC4.PT3 (April 2018)
Odenbreit, Christoph UL; Vigneri, Valentino UL

Report (2021)

The unsafety of current design rules for novel types of open-trough deck geometries for the resistance of headed studs in profiled steel sheeting is well known [1] and it was the main reason behind the ... [more ▼]

The unsafety of current design rules for novel types of open-trough deck geometries for the resistance of headed studs in profiled steel sheeting is well known [1] and it was the main reason behind the nomination of CEN/TC250/SC4- Task SC4.T3: “Revised rules for shear connection in the presence of modern forms of profiled sheeting”. During the RFCS research project “DISCCO” (RFCS-CT-2012-00030) [1], a mechanical model was developed on the basis of a large literature study and previous studies [2, 3, 4, 5, 6] while the corresponding design equations were presented by CEN/TC250/SC4.PT3 and further enhanced during the Research Project “ShearCON” of University of Luxembourg. In order to let the current rules of EN 1994-1-1 6.6 (Eq.(2) and (3)) as unchanged as possible, the limits of its suitable field of applicability (Database B1) was investigated thoroughly by means of the statistical procedure of EN 1990 D.8 [7]. The newly proposed equations (Eq. (7) and (8)) apply only to the cases outside these limits (Database B2). In this way, the proposed solution is able to restore the level of safety to its initial value, so that the partial safety factor for the shear connection ϒV=1.25 is adequate. Conversely, the current situation (without including the new design equations) would need a much higher partial safety factor as shown below. [less ▲]

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See detailEtude experimentale et numerique du comportement mecanique d'une solution innovante de pourte mixte Acier-Beton en forme de U
Turetta, Maxime; Martin, Pierre-Oliver; Khelil, Abdelouahab et al

in Revue construction métallique (2021), 1

Pour conquérir de nouvelles parts de marché ou simplement défendre ses positions sur un marché très concurrentiel, il faut sans cesse améliorer la compétitivité des procédés constructifs utilisés. La ... [more ▼]

Pour conquérir de nouvelles parts de marché ou simplement défendre ses positions sur un marché très concurrentiel, il faut sans cesse améliorer la compétitivité des procédés constructifs utilisés. La prise en compte de la réglementation incendie s’avère avoir une grande influence sur les matériaux constructifs et peut remettre en cause certains avantages de la filière métallique. Les solutions mixtes acier-béton constituent un très bon compromis, permettant d’optimiser la consommation des matériaux, de réduire les temps de montage tout en répondant aux exigences réglementaires en matière de sécurité incendie même les plus contraignantes notamment pour des établissements recevant du public (ERP), des sites sensibles ou encore des immeubles de grande hauteur (IGH). [less ▲]

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See detailDemountable and reusable construction system for steel-concrete composite structures
Odenbreit, Christoph UL; Kozma, Andras UL

in Odenbreit, Christoph; Kozma, Andras (Eds.) Demountable and reusable construction system for steel-concrete composite structures (2020, October 30)

In the face of climate change and the depletion of finite resources, sustainability is becoming increasingly important recently. This is especially true in the construction industry that is responsible ... [more ▼]

In the face of climate change and the depletion of finite resources, sustainability is becoming increasingly important recently. This is especially true in the construction industry that is responsible for the 11% of global carbon dioxide emissions. Besides the technological improvements, the emissions can be further reduced by the application of the principles of the circular economy. This concept is based on the efficient allocation of resources. Three terms are frequently used when talking about this concept: reduce, reuse and recycle. Reducing is cut-ting back on the amount of waste we produce, reusing is finding a new way to use our products so that they do not be-come waste, and recycling is using the materials of our products to produce new materials. The traditional life-cycle of a building usually follows a linear model from the extraction of the raw materials through material production, component manufacturing, construction and building use, until when finally the building is demolished and most of the materials become debris and go into landfill. This is in direct opposition with the concept of circular economy. With proper considerations at the design stage, it is possible to deconstruct whole buildings and re-erect them elsewhere. In the frame of the RFCS Research Project “REDUCE” of the European Commission, a demountable and reusable construction system for steel-concrete composite structures has been recently developed. The system is based on a modular “kit-of-parts” system that uses prefabricated and standardised elements that are easy to manufacture and to assemble with the help of standardised connections. The elements were designed in a systematic way such that, a wide variety of different configurations are possible. In this system, the geometry of all elements respects the planning grid that is based on a basic module size. The research included the development and structural testing of novel demountable and adjustable structural solutions including beam-to-slab, beam-to-beam and beam-to-column connections. During the development of the structural solutions the following aspects were considered: structural performance, safety, installation and tolerances, demountability, corrosion resistance, aesthetics, economy, adaptability, standardisation and environmental impact. The laboratory testing was supplemented by nonlinear numerical studies using the finite element software ABAQUS. Based on the results and the experiences obtained throughout the research project, a design proposal was prepared. One objective of the project was to find structural solutions that are easily applicable and compatible with the current standard de-sign rules. The proposed beam-to-beam and beam-to-column joint is in the scope of EN1993-1-8. The new shear connections behave differently than the traditionally applied welded studs. The cor-responding standard would not allow the equidistant placement of the connectors nor the application of the partial shear theory. This would make the use of demountable shear connections complicated and uneconomical. In order to overcome this issue, a simple algorithm was developed that transforms the elastic-brittle shear connection behaviour into an equivalent ductile rigid-plastic behaviour so that the Eurocode 4 design rules for the determination of the moment resistance of composite beams with partial shear connection remain applicable. The design proposal also contains recommendations to maximize the reuse potential of the building components. This paper presents a general overview of the developed construction system and the corresponding laboratory tests and numerical studies as well as recommendations for the design and application of de-mountable and reusable composite structures. [less ▲]

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See detailInvestigation on the flexural behavior of an innovative U shaped steel concrete composite beam
Turetta, Maxime; Odenbreit, Christoph UL; Khelil, Abdelouahab et al

in Steel and Composite Structures (2020), 34(3), 441--452

Within the French CIFRE research project COMINO, an innovative type of composite beam was developed for buildings that need fire resistance with no additional supports in construction stage. The developed ... [more ▼]

Within the French CIFRE research project COMINO, an innovative type of composite beam was developed for buildings that need fire resistance with no additional supports in construction stage. The developed solution is composed of a steel U-shaped beam acting as a formwork in construction stage for a reinforced concrete part that provides the fire resistance. In the exploitation stage, the steel and the reinforced concrete are acting together as a composite beam. This paper presents the investigation made on the load bearing capacity of this new developed steel-concrete composite section. A full-scale test has been carried out at the Laboratory of Structural Engineering of the University of Luxembourg. The paper presents the configuration of the specimen, the fabrication process and the obtained test results. The beam behaved compositely and exhibited high ductility and bending resistance. The shear connection in the tension zone was effective. The beam failed by a separation between the slab and the beam at high deformations, excessive shear forces conducted to a failure of the stirrups in this zone. The test results are then compared with good agreement to analytical methods of design based on EN 1994 and design guidelines are given. [less ▲]

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See detailDemountable Precast Concrete Systems
Odenbreit, Christoph UL; Kozma, András

in Reduce, reuse and demountability using steel structures and the circular economy (2019, October 08)

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See detailDemountable Steel Connections
Lam, Dennis; Odenbreit, Christoph UL; Yang, Jie et al

Scientific Conference (2019, October 08)

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See detailParametric study on non-ductile demountable shear connectors
Odenbreit, Christoph UL; Kozma, Andras UL

in ce/papers (2019, September), 3(3-4), 283-288

The basic principle of the circular economy is to reduce or totally eliminate waste and carbon dioxide production with the help of a multiple, efficient usage of resources. The application of reusable ... [more ▼]

The basic principle of the circular economy is to reduce or totally eliminate waste and carbon dioxide production with the help of a multiple, efficient usage of resources. The application of reusable structural elements plays an important role and can contribute essentially to a low-carbon future. Within the European research project REDUCE (Grant Agreement number: 710040), composite beams and steel-based flooring systems, which are demountable and reusable, have been developed and investigated. The experimental investigations showed that the structural behaviour of the newly developed shear connectors differs from the behaviour of the traditionally applied welded studs. Some behave in a non-ductile way. In order to assess, how far the regulations of EN1994-1-1 for shear connections can still be applied, parametric studies have been conducted. The respective numerical models were developed with the use of the commercially available finite element software ABAQUS® and were validated against the experimental observations. The effects of the lack of ductility of the shear connectors on the structural behaviour of the entire composite beam was examined with different types of shear connectors, shear connector layouts and material grades. This contribution presents the underlying laboratory tests as well as the results of the supplementing numerical parameter studies. The outcome provides valuable information for future design guidance concerning the use of demountable shear connectors in composite beams. [less ▲]

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See detailDifferent load‐bearing mechanisms in headed stud shear connections in composite beams with profiled steel sheeting
Vigneri, Valentino UL; Odenbreit, Christoph UL; Lam, Dennis

in ce/papers (2019, September), 3(3-4), 231-236

The current regulations of EN1994-1-1 for headed stud shear connections in composite beams with profiled sheeting lead, for some configurations, to an over-estimation of the load-bearing capacity. Since ... [more ▼]

The current regulations of EN1994-1-1 for headed stud shear connections in composite beams with profiled sheeting lead, for some configurations, to an over-estimation of the load-bearing capacity. Since these design equations are based on empirical considerations, they are not able to capture the real mechanical behaviour of the connector and they do not consider appropriately the influence of the geometry of sheeting on the shear capacity. For this reason, the load-bearing mechanisms of the shear connection are identified in this work with the support of experimental and numerical results. According to the static system presented, the concrete rib is modelled as a system of diagonal struts acting simultaneously in combination with the stud in bending. It is observed that at 2÷4 mm slip, a ?Strut and beam? mechanism prevails where the resistance of the connector depends mostly on the plastic hinges activated in the stud and on the capacity of the diagonal strut in front of it. By increasing the slip (ca. 4÷10 mm), the surrounding concrete progressively crushes while the tensile stresses at the edge of the rib reach the tensile strength of the material. As a consequence of this loss of rotational stiffness, the bending capacity developed in the stud reduces and the upper hinges gradually moves towards the slab. At higher displacements (ca. 20÷40 mm), due to nonlinear geometric effects, high tensile forces develop in the stud and the load is carried through a ?Strut and Tie? resistance mechanism, if the embedment of the stud is sufficient. By further increasing the slip, the whole rib rotates or the failure occurs either for concrete pull-out or stud rupture. This contribution describes the sequence of the activated load-bearing mechanisms in headed stud shear connections with profiled steel sheeting at different displacements. [less ▲]

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See detailDifferent load bearing mechanisms in headed stud shear connectors for composite beams with profiled steel sheeting
Vigneri, Valentino UL; Odenbreit, Christoph UL; Lam, Dennis

in Steel Construction (2019), 12(3), 184-190

The current design rules of EN 1994-1-1 covering headed stud shear connectors for composite beams with profiled sheeting lead, in some cases, to an overestimation of the load bearing capacity. Owing to ... [more ▼]

The current design rules of EN 1994-1-1 covering headed stud shear connectors for composite beams with profiled sheeting lead, in some cases, to an overestimation of the load bearing capacity. Owing to their empirical nature, these equations are not able to capture the real behaviour of the connector. Therefore, the load bearing mechanisms of the shear connection are identified in this work with the support of experimental and numerical results. According to the static system proposed, the concrete rib is modelled as a system of diagonal struts in combination with the stud in bending. It was observed that at 1-4 mm slip, a 'strut and beam' mechanism prevails, where the resistance of the connector depends on the activation of the plastic hinges in the stud and on the capacity of the diagonal strut in front of it. By increasing the slip (approx. 4-10 mm), the surrounding concrete gradually crushes, while the tensile stresses at the edge of the rib reach the tensile strength of the material. Because of this loss of rotational stiffness, the bending moment in the stud decreases and the upper plastic hinge gradually moves towards the slab. At higher displacements (approx. 20-40 mm), high tensile forces develop in the stud due to non-linear geometric effects and the load is carried through a 'strut and tie' resistance mechanism, provided that the embedment of the stud is sufficient to prevent the rotation of the rib. As the slip increases further, failure occurs either in the form of concrete pull-out or stud rupture. [less ▲]

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See detailRotation capacity of composite joints for slim-floor beams
Duarte da Costa, Job; Obiala, Renata; Odenbreit, Christoph UL

in Stahlbau (2019), 88(7), 675--684

The analysis of a composite beam-to-column structure requires knowledge about, on the one hand, the behaviour of beams and columns and, on the other, the joints between such elements. For beam-to-column ... [more ▼]

The analysis of a composite beam-to-column structure requires knowledge about, on the one hand, the behaviour of beams and columns and, on the other, the joints between such elements. For beam-to-column joints, for example, the lack of appropriate design rules forces structural engineers to model joints as pinned, despite the fact that a certain joint rigidity and bending resistance is available because of the upper reinforced concrete slab. In this context, a research program with experimental and numerical investigations was initiated at the University of Luxembourg [1]. This aim of this research was to identify the influence of two major joint components – the reinforced concrete slab and the steelwork connection – on the behaviour of composite joints under a hogging bending moment. Eight experimental tests were performed on... [less ▲]

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See detailCharacterisation of demountable shear connector systems in composite beams
Kozma, Andras UL; Odenbreit, Christoph UL; Braun, Matthias Volker UL

Scientific Conference (2019, July 04)

Reusable structures can contribute to a resource-efficient low-carbon future on the basis of the principles of the circular economy. This paper presents a comparison of different demountable shear ... [more ▼]

Reusable structures can contribute to a resource-efficient low-carbon future on the basis of the principles of the circular economy. This paper presents a comparison of different demountable shear connector systems that facilitate recyclability and reusability of steel-concrete composite structures with the performance of traditional ones. In the Laboratory of the ArcelorMittal Chair of Steel and Façade Engineering at the University of Luxembourg 15 push-out tests and 2 full-scale beam tests have been carried out using different bolted shear connection systems suitable for reuse after the end of life of the respective building. The analysed shear connector systems have been evaluated based on their resistance, slip capacity, stiffness, ductility and ease of fabrication, assembly and disassembly. The experimental work was supplemented by numerical simulations performed with the finite element software Abaqus®. The developed numerical models were validated against the experimental observations. The experimental and numerical results provide information for future design guidance concerning the use of demountable shear connectors in composite beams. [less ▲]

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See detailEquations to predict the shear connection capacity of composite beams with slender profiled steel sheeting
Odenbreit, Christoph UL; Vigneri, Valentino UL; Lam, Dennis

Scientific Conference (2019, July)

The rules of EN1994-1-1 for shear connections in composite beams with deep profiled sheeting sometimes lead to an overestimation of the load bearing capacity of the respective shear connection. The ... [more ▼]

The rules of EN1994-1-1 for shear connections in composite beams with deep profiled sheeting sometimes lead to an overestimation of the load bearing capacity of the respective shear connection. The estimation of the impact of the sheeting shape on the calculated connection resistance is based on test results from the late seventies until the early nineties. Meanwhile, new products have appeared on the market with the target to reduce the volume and weight of the concrete in order to maximize the slab efficiency. However, the corresponding effects onto the shear connection have been underestimated because the use of deeper and more narrow deck rib lead to a more slender profile with a changed failure behaviour. Instead of the shearing-off failure of the stud, a combination of concrete cone failure and plastic bending of the stud – with one or two plastic hinges - was identified in laboratory tests. Based on the observed failure mechanisms, a new mechanical model with respective analytical equations for the shear resistance of headed studs in profiled steel sheeting was proposed. The new model extends the yield hinge mechanism, which was developed by Lungershausen [1], to more precisely predict the formation of the number of yield hinges depending on the mechanical and geometrical properties with the support of a finite element model. The complete equations consider the geometry of the stud and the steel decking as well as the material strengths of the stud and concrete. The statistical evaluation shows a good accordance with the developed model and analytical design equations. This contribution presents the new design equations and their background describing the mechanical model, the numerical study and statistical evaluation of push-out test results. [less ▲]

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See detailTragverhalten von CoSFB-Dübeln
Braun, Matthias; Obiala, Renata; Schäfer, Markus UL et al

in Stahlbau (2019), 88(2019)(Heft 7),

Slim-floor or shallow floor construction is characterized by the integration of a steel beam into a slab. The activation of a composite action between the steel section and the concrete slab leads to a ... [more ▼]

Slim-floor or shallow floor construction is characterized by the integration of a steel beam into a slab. The activation of a composite action between the steel section and the concrete slab leads to a significant increase of the bending capacity and the stiffness of the beam, allowing for larger beam spans. This paper presents a fundamentally new method for assessing the load-bearing capacity of CoSFB-Dowels, which ensures a composite action of a composite slim-floor beam (CoSFB). Based on detailed analysis of push-out tests, extensive numerical simulations were performed in order to identify the contribution of various parameters on the load-bearing capacity. Finally, an analytical formulation of the load-bearing capacity is presented, which has been derived by applying a simple second order plasticity approach. [less ▲]

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See detailPush-out tests on demountable shear connectors of steel concrete composite structures
Kozma, Andras UL; Odenbreit, Christoph UL; Braun, Matthias Volker UL et al

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 ▲]

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See detailMeasuring mode I fracture properties of thick-layered structural silicone sealants
Rosendahl, P. L.; Staudt, Y.; Odenbreit, Christoph UL et al

in International Journal of Adhesion and Adhesives (2019), 91

The failure hyperelastic structural sealant joints is a fracture mechanics problem. Its modeling requires knowledge of the material property fracture toughness. The present work describes a methodology ... [more ▼]

The failure hyperelastic structural sealant joints is a fracture mechanics problem. Its modeling requires knowledge of the material property fracture toughness. The present work describes a methodology for determining the mode I bulk material fracture toughness of structural silicone sealants. The concept is demonstrated using DOWSIL™ 993 as an example. In total we manufactured, tested and evaluated 13 DCB specimens of 6mm and 12mm adhesive thickness. The fracture toughness is identified from J-integral measurements. The theory for determining the J-integral at finite deformations is laid out and an automated data analysis procedure is suggested. The presented approach further allows... [less ▲]

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