A novel shear connection and analysing algorithm to allow for circular economy in steel-concrete and steel-timber composite construction (LAC24.A)

The composite construction in steel and concrete is well known and established already since mid of the last century. However, the need to lower carbon dioxide emissions is driving industries across all sectors to pursue environmentally sustainable alternatives. Consequently, timber is gaining global recognition as structural material. In addition, the integration of circular economy principles in construction lowers the carbon emissions drastically, because building products are no longer being disposed of or recycled, but rather being re-used at the respective production level. Within the research projects "REDUCE" (financed by the European Union) and the project "Prefa-SeTi" (financed by the Fonds National de la Recherche Luxembourg, ArcelorMittal and the construction company Prefalux), a special type of shear connector was developed. This connector offers several key advantages: (i) the activation of the steel-composite action in steel-concrete as well as steel-timber, (ii) a modularisation, (iii) an easy demountability and (iv) reusability of the steel element and the respective slab elements. However, this demountable shear connection exhibits fundamentally different load slip behaviour compared to the well known welded shear connections. To address this, an additional algorithm was developed. This algoritm allows to transfer any arbitrary load-slip curve into a simple "effective shear resistance", which can be used to determine the bending capacity of a composite section with full or with a partial degree of shear connection. This contribution presents (i) in the first step the developed shear connector for both, the steel-concrete and steel-timber composite construction and (ii) in the second step the methodology of the proposed algorithm, how the experimentally obtained and any arbitrary load-slip curve can be translated into the mentioned effective shear connection resistance. (iii) In the last step, the results are compared to large scale tests, which have been conducted in the Structural Engineering Laboratory at the University of Luxembourg.