Verification of spread footing for punching shear

The program allows for the verification of spread footing for punching shear or for the design of shear reinforcement. The critical section loaded in shear U_cr is distant from the column edge by one half of the footing thickness. It is loaded by the prescribed moments M_x, M_y and by the shear force Q_r provided by:

where:	A	-	area of footing
	Q	-	assigned vertical force developed in column
	At	-	hatched area in fig.

Dimensioning of shear reinforcement area At

The program computes the maximal shear force Q_dmax developed in the critical section, the shear force transmitted by concrete with no shear reinforcement Q_bu, and the maximal allowable force Q_max:

where for: is: or else:

For Q_dmax < Q_bu no shear reinforcement is needed.

For Q_dmax > Q_buand Q_dmax < Q_max the shear reinforcement must be introduced. The ultimate shear force is given by:

where:	Ucr	-	critical cross-section span
	α	-	is angle of crooks
	As	-	overall area of crooks in footing

For Q_dmax > Q_max the shear reinforcement cannot be designed. It is therefore necessary to increase the cross-section height.