Analyzing the minimum degree of shear connection for composite beams with prestressed dismountable shear connections (LAC25.A1)

There is a pressing need to reduce carbon dioxide emissions in the building and construction sector in order to achieve carbon neutrality by 2050. This sector plays a significant role in global emissions, accounting for approximately 37% of energy and process emissions of which the manufacturing processes for materials such as concrete, steel, aluminum, bricks, and glass contribute around 9% of CO2 emissions in the sector.
The target of reduced carbon emissions needs deeper investigations into the life cycle of materials and structures. This forces to think beyond manufacturing and transport and switch from a linear to a circular economy. One possibility is the use of composite structures which enabled a circular lifecycle and reusability of the composite materials e.g., through demount ability.
The previous RFCS (Research Fund for Coal and Steel) research project “REDUCE” (grant no. 710040, 2016), succeeded in dismountable, reusable and recyclable steel- and steel-concrete composite structures. However, the behavior of bolted connections, is different than headed, welded shear studs. Dismountable, prestressed shear connectors have a more tri-linear increasing load-slip behavior, where at about half of the maximum loadbearing capacity the slip increases due to a play in the space of the shear connector hole without an increase in the load. The behavior arose questions about what shear force can be activated in the shear connection.
To elaborate on this, an analytical algorithm was developed and a numerical study using ABAQUS finite element software was undertaken to determine the behavior of the slip, especially for beams with a low degree of shear connection, which was then compared to the maximum allowable slip of 6mm from EN1994-1-1.

The objective of this contribution looks at the solution of the shear connection between the concrete slap and the steel beam, explains the algorithm and elaborates, if the minimum degree of shear connection of EN1994-1-1 can also be applied with the new bolted shear connections and the respective analytical algorithm.