Characterisation of demountable shear connector systems in composite beams

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 ▲]

Numerical evaluation of the plastic hinges developed in headed stud shear connectors in composite beams with profiled steel sheeting

in Structures (2019), 21

For composite beams using novel steel sheeting, the current Eurocode 4 rules sometimes overestimate the load-bearing capacity of headed stud shear connectors. This is due to the larger rib heights and the ... [more ▼]

For composite beams using novel steel sheeting, the current Eurocode 4 rules sometimes overestimate the load-bearing capacity of headed stud shear connectors. This is due to the larger rib heights and the smaller rib widths in comparison with the old studies, which have been carried out to calibrate the current design equations. The RFCS Project “DISCCO” investigated this phenomena and the working group under mandate M515, CEN/TC250/SC4/SC4.T3 is enhancing this equation and working on a proposal to be taken over in the new version of Eurocode 4. The proposed new equation covers the failure behaviour of the shear connection more in detail. The test results show, that the failure consists in a combined concrete cone and stud in bending. Due to the geometry of novel steel sheeting, the load bearing capacity of the headed stud shear connector is no more limited by its shear capacity, but by its bending capacity. A 3D non-linear finite element model is developed and validated through the support of the DISCCO push-out tests. A good agreement between numerical and experimental results in terms of force-slip behaviour is achieved. Special attention of this work lies on the numerical evaluation of the number of plastic hinges n y : a stress-based procedure is presented and the results are compared to the equations presented for new Eurocode 4. The numerical simulations show that the upper plastic hinge moves up as the slip increases due to the progressive crushing of the concrete in the rib. From the parametric study, it turns out that n y is linearly proportional to the embedment depth. Compared to pre-punched hole decking, through-deck welding specimen activates less plastic hinges in the studs because of the higher stiffness provided at the base of the stud. [less ▲]

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

in Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures (2018, June 27)

The deconstruction of steel-concrete composite structures in buildings and the later separation of the materials is a labour- and cost intensive work. The shear studs are welded on the steel beam and ... [more ▼]

The deconstruction of steel-concrete composite structures in buildings and the later separation of the materials is a labour- and cost intensive work. The shear studs are welded on the steel beam and imbedded in the concrete deck and a large amount of cutting work becomes necessary. As a result, recycling is difficult and the potential for reusing entire elements is lost. The carbon footprint of composite structures could be decreased by application of the principles of “design for deconstruction and reuse”. This paper presents a desk top study and 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 uses in order to verify their performance focusing on shear strength, stiffness, slip capacity, ductility and ability of demounting. The investigated systems included pre-stressed and epoxy resin injection bolts, solid slabs and composite slabs with profiled decking. The results showed that the tested demountable shear connections could provide higher shear resistance than conventional shear connections. The critical failure mode is shear failure of the bolts, while there was no visible damage observed on the connected members. Most of the tested connections could fulfil the ductility requirement according to by Eurocode 4. 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 ▲]

Flachdecken in Verbundbauweise - Bemessung und Konstruktion von Slim-Floor Trägern

in Kuhlmann, Ulrike (Ed.) Stahlbaukalender 2018 (2018)

Design and State of the Art for composite shallow floor beams in steel and concrete.

Investigation of the Load-Bearing Behaviour of CoSFB-Dowels

Doctoral thesis (2018)

This Thesis is the first PhD thesis written about CoSFB-Dowels. Therefore, focus of the scientific work presented here, was on the identification of parameters influencing the load-bearing behaviour in ... [more ▼]

This Thesis is the first PhD thesis written about CoSFB-Dowels. Therefore, focus of the scientific work presented here, was on the identification of parameters influencing the load-bearing behaviour in general and on parameters contributing to the load-bearing capacity of CoSFB-Dowels in detail. A CoSFB-Dowel is an innovative shear connector for steel-concrete composite slim-floor beams. It consists of circular openings drilled in the web of the steel section with reinforcement bars passing through and filled with normal concrete in-situ. Push-out tests have been performed already in an earlier research project initiated by the author. In this Thesis, detailed analysis of the test results was done and a finite element model developed simulating the push-out tests, which led to an improved understanding of the overall load-bearing behaviour. Further, the numerical model was used to identify and to evaluate components contributing to the stiffness, to the linear-elastic load and to the maximum load. The findings of this research led to the formulation of a mechanical model and an analytical method to evaluate the load-bearing capacity of a CoSFB-Dowel. The analytical method was validated with the test results. This Thesis is concluded by a proposal allowing for a conservative determination of the design resistance of CoSFB-Dowels. [less ▲]

Numerical simulation of the load bearing behaviour of concrete dowels in slim-floor construction – CoSFB

in Eurosteel 2017 (2017, September 13)

In this paper the current status of an ongoing research on composite slim-floor beams (SFB) with concrete dowels (CoSFB) is presented, Fig. 1. Using commercial software ABAQUS [1], a 3D solid model with ... [more ▼]

In this paper the current status of an ongoing research on composite slim-floor beams (SFB) with concrete dowels (CoSFB) is presented, Fig. 1. Using commercial software ABAQUS [1], a 3D solid model with non-linear material laws has been developed to simulate the load bearing behaviour of concrete dowels numerically. The model was validated by the results of experimental investigations, which have proven a high stiffness of the concrete dowels under service loads and their ductile behaviour in reaching the load bearing resistance [2], [3]. Further, in comparison to traditional shear studs, the thickness of the concrete cover above the upper flange of composite SFB with concrete dowels can be reduced to a minimum, which leads to an optimized floor thickness and overall to a more economic construction. Main parameters defining the FE model, which influence the load bearing capacity, the behaviour and failure of the shear connection were identified and described in this paper. Available results and analysis from the parametric study are described. Wide range of results obtained from the numerical study will be used to derive an analytical model to allow predicting the load bearing resistance of the system. [less ▲]

Design of single span beams in SLS and ULS using semi-continuous beam-to-column joints - Part 1: Beams with constant bending stiffness and joints according to EN 1993-1-8

in Steel Construction (2016), 9(1), 1-15

This article explains a method for determining how semi-continuous joints influence the deflection, natural frequency and bending moment distribution of single-span beams with constant inertia under ... [more ▼]

This article explains a method for determining how semi-continuous joints influence the deflection, natural frequency and bending moment distribution of single-span beams with constant inertia under uniformly distributed load. The method is adequate for simple hand calculations, allowing the structural engineer to assess potential savings already in the pre-design phase. Further, the economical potential of semi-continuous joints according to EN 1993-1-8 is demonstrated by an application example. [less ▲]