Verification of Spread Footing for Punching Shear
It is loaded by the prescribed moments MEdx, MEdy and by the shear force VEd provided by:
where: | A | - | area of footing |
V | - | assigned vertical force developed in column | |
At | - | hatched area in fig. |
Dimensioning of shear reinforcement area At
The program constructs control sections at distances "a" from 0,5d to 2d in case of footing without shear reinforcement. In case of reinforced footing, the distances are from 0,5d to 4d, where d is the effective depth of footing. The shear reinforcement is considered in control sections, which are in the distance of less than 2d from the column. The control sections are considered in intervals of 0,25d.
The load stress vEd in each control section is found using 6.4.3 (3),
the punching shear resistance of footing without shear reinforcement vRd,c follows from 6.4.4 (2)
and if necessary the punching shear resistance of reinforced footing vRd,cs is given by 6.4.5 (1).
Furthermore, the compression chord resistance at the column perimeter vRd,max is calculated according to 6.4.5 (3). vRd,max depends on column dimensions and the footing thickness.
For vEd < vRd,c no shear reinforcement is needed.
For vEd > vRd,c and vEd < vRd,max the shear reinforcement must be introduced.
For vEd > vRd,max the shear reinforcement cannot be designed. It is therefore necessary to increase the cross-section height.
The control section ratio of load and resistance with the highest utilization is considered as critical and marked in the program.
Standard values of coefficients ν, νmin are built-in the program - these values can also be input by the user depending on the selected National annex.