Shear Capacity (Eurocodes)

Shear capacity is calculated through the following expression according to Annex A of EN1998-3:2005, as controlled by the stirrups, accounting for the reduction due to the plastic part of ductility demand.

Where γel is equal to 1,15 for primary seismic elements and to 1,0 for secondary ones, the other variables are calculated as defined in A.3.3.1 of Annex A of EN1998-3.

Notes

  1. The shear strength of a concrete wall is not taken greater than the value corresponding to failure by web crushing, VR,max, which under cyclic loading is calculated according to A3.3.1(2) of Annex A of EN1998-3:2005 from the following expression:

  1. If in a concrete column the shear span ratio (LV/h) at the end section with the maximum of the two end moments is less or equal to 2, the shear strength is not taken greater than the value corresponding to the failure by web crushing along the diagonal of the column after flexural yielding, VR,max, which under cyclic loading is calculated according to A3.3.1(3) of Annex A of EN1998-3:2005 from the following expression:

Where δ is the angle between the diagonal and the axis of the column (tanδ = h/2LV).

Concrete Jacketing
The following assumptions are made in order to evaluate the strength of the jacketed members, according to Annex A of EN1998-3:2005: (i) the jacketed element behaves monolithically, (ii) the full axial load is assumed to act on the jacketed member, disregarding the fact that the axial load is originally applied to the old column, and (iii) the concrete properties of the jacket are assumed to apply over the full section of the element.

The value for the shear capacity of the jacketed members that is adopted in the capacity verifications depend on the corresponding value calculated under the assumptions above, according to the following equation of Annex A of EN1998-3:2005:

FRP Wrapping
According to section A.4.4.2(9) of Annex A of EN1998-3:2005, in members with their plastic hinge region fully wrapped in an FRP jacket over a length at least equal to the member depth, the cyclic resistance VR, may be calculated from expression (A.12) of EC8: Part 3 adding in Vw the contribution of the FRP jacket to the shear resistance. The contribution of the FRP jacket to Vw is computed through the following expression:

where ρf is the geometric ratio of the FRP, z the length of the internal lever arm and fu,fd the design value of the FRP ultimate strength.