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Shear Capacity – Crossing Borders

Barten, Piet

Abstract In order to get the Eurocodes accepted, it was necessary to allow national choices with regard to parameters where no agreement between the countries involved could be reached. For the determination of the shear capacity EN1992-1-1 defines eight parameters subject to national choices (and EN1992-2 even introduces two more). In addition, also for the determination of the design load, several parameters subject to national choices are included. As a result, despite the introduction of the Eurocode, there are still considerable differences between individual countries in shear design. A reason to have a closer look on what is really happening in the structures. The basis underlying to the Eurocode can be found in the Model Code 2010 (MC 2010) in which three different approaches are described to validate the safety of structures in the Ultimate Limit States by numerical simulations using non-linear constitutive models. EN 1992-1-1, clause 5.7 allows for the use of such non-linear models. A FEA package validation has been executed based on experiments, to specifically demonstrate that FE models are appropriate. The validation demonstrated the available constitutive material models are adequate to describe the behavior of concrete and results are similar to the experimental results. After the successful validation, the same approach has been applied for a tunnel structure. From the non-linear simulations for this tunnel structure, the important conclusion can be drawn that the MC2010 methods give comfortable factors of safety and that the Eurocode design based on recommended parameters will give conservative, lower bound design capacities. Using sophisticated models for the tunnel structure a considerable reduction of the required shear reinforcement compared to a straight forward application of the Eurocode could be justified.