The EN 1992-2004 Punching Shear Model

The punching shear analysis and design approach uses the EC2 provisions for the basis of the implementation. Some condition specific EC2 provisions were generalized using CEB-FIP 90. The implementation also implements suggestions in TR-43 regarding treatment of precompression in the shear strength equations.

A control perimeter (u₁) is defined at 2d from the periphery of area of application of force. This control perimeter is constructed so as to minimize its length. The corners of the perimeter are rounded.

For slab edges located within the punching check, additional control perimeters will be generated by projecting perpendicular lines from the original control perimeter to the slab edges. Additionally, control perimeters will be generated for each basic slab shape, cap, etc. This could result in a number of basic control perimeters.

To calculate the perimeter stresses, a plastic distribution of stresses caused by the eccentricity between the load/reaction and the control perimeter is superimposed with the shear stresses caused by the concentric loading to calculate a complete stress distribution on the perimeter. Where there are eccentricities in two orthogonal directions, they are considered simultaneously. The k factor in EC2 equation 6.39 is applied to the unbalanced moment after the column forces are transformed to the plastic neutral axis of the control perimeter.

EC2 clause 6.4.3(3) requires the calculation of a β factor on the basic control perimeter. The same β factor is then applied to all subsequent perimeter calculations. This simplification is made due to the complexity in the plastic section calculations. RAM Concept does not make this assumption, but instead calculates and applies an appropriate β factor for each perimeter calculated. This is in accordance with the approach for the cutoff section in CEB-FIP 90.