Shear capacity (Beams: EC3 Eurocode)
Major and minor axis shear

No account is taken of fastener holes in the flange or web  see 6.2.6 (7)

Shear is not combined with torsion and thus the resistance is not reduced as per 6.2.6 (8)
Web Shear buckling
Shear web buckling design applies to rolled and plated I/H sections only.
National Annex dependency
Plates with unstiffened webs are checked for shear web buckling where:
h_{w} / t_{w} > 72 ε / η
where
ε = √ (235 / f_{w}
η is NA dependant and is defined in the table below:
National Annex  η  Applicable to 

Eurocode value  1.20  Up to and including S460, else use η = 1.00 
UK  1.00  All steel grades 
Irish  1.00  All steel grades 
Malaysia  1.00  All steel grades 
Singapore  1.00  All steel grades 
Contribution from flanges
When the flange resistance is not fully utilized in resisting the bending moment (M_{Ed} <M_{f,Rd}), the contribution from the flanges is taken as:
V_{bf,Rd} = (b_{f} t^{2}_{f} f_{yf}) / (c γ_{M1}) * (1  (M_{Ed}/M_{f,Rd})^{2})
where

b_{f} and t_{f} are taken for the flange which provides the least axial resistance

b_{f} is not taken as larger than 15εt_{f} on each side of the web

M_{f,Rd} is the moment of resistance of the cross section consisting of the effective area of the flanges only

c = a (0.25 + 1.6b_{f} t_{f}^{2} f_{yf} / t h_{w}^{2} f_{y}f_{w})

a is the distance between stiffeners
As we are only designing for the case where no stiffeners are being used, a → ∞ therefore c → ∞ so V_{bf,Rd}→ 0.
Contribution from the web
The contribution from the web is taken as:
V_{bw,Rd} = (x_{w} f_{yw} h_{w} t) / (√3γ_{M1})
x_{w} ≤ η
Design resistance
The design resistance for shear is taken as:
V_{b,Rd} = V_{bw,Rd} + V_{bf,Rd} ≤ η (f_{yw} h_{w} t) / (√3γ_{M1})
Influence of shear
According to 7.1 of EN 199315 provided V_{Ed} ≤ 0.5 V_{bw,Rd} the design resistance to bending moment and axial force does not need to be reduced to allow for shear force.
In Tekla Structural Designer V_{Ed} is restricted to 0.5 V_{bw,Rd}, values above this are deemed beyond scope.
This restriction is only applicable if h_{w} / t_{w} > 72 ε / η
Assumptions
The following points should be noted:

Nonrigid end post is a more conservative approach than a rigid end post.

Physical support conditions can be taken as equivalent to "transverse stiffeners at supports only".

It is assumed there is negligible contribution to the design shear force VEd from shear from torque

All hole cut outs are small in accordance to section EN 199315:2006 2.3

As the case being designed for is where no stiffeners are being used, a → ∞ therefore c → ∞ so V_{bf,Rd}→ 0.

If a grade of steel is used other than S335, S355 and S460, η will be taken as 1.00 regardless of National Annex.