# Figure Column flange with backing plates

6.2.5 Equivalent T-stub in compression

(1) In steel- to-concrete joints, the flange of an equivalent T-stub in compression may be used to model the design resistances for the combination of the following basic components:

- the steel base plate in bending under the bearing pressure on the foundation,

- the concrete and/or grout joint material in bearing.

(2) The total length leff and the total width beff of an equivalent T-stub should be such that the design compression resistance of the T-stub is equivalent to that of the basic joint component it represents.

NOTE: The effective length and the effective width of an equivalent T-stub are notional lengths and may be smaller than or equal to the physical dimensions of the basic joint component it represents.

(3) The design compression resistance of a T-stub flange AC,Rd should be determined as follows:

where:

beff is the effective width of the T-stub flange, see 6.2.5(5) and 6.2.5(6) leff is the effective length of the T-stub flange, see 6.2.5(5) and 6.2.5(6) fd is the design bearing strength of the joint, see 6.2.5(7)

The forces transferred through a T-stub should be assumed to spread uniformly as shown in Figure 6.4(a) and (b). The pressure on the resulting bearing area should not exceed the design bearing strength f and the additional bearing width, c, should not exceed:

where:

t is the thickness of the T-stub flange; fy is the yield strength of the T-stub flange.

Where the projection of the physical length of the basic joint component represented by the T-stub is less than c, the effective area should be taken as indicated in Figure 6.4(a)

Where the projection of the physical length of the basic joint component represented by the T-stub exceeds c on any side, the part of the additional projection beyond the width c should be neglected, see Figure 6.4(b).

(a) Short projection (b) Large projection