Member strength checks (ULS) (Composite beams: EC4 Eurocode)
It is assumed that there are no loads or support conditions that require the web to be checked for transverse force. (clause 6.5)
Member strength checks are performed at the point of maximum moment, the point of maximum shear, the position of application of each point load, and at all other points of interest along the beam.
Shear capacity (Vertical)
The resistance to vertical shear, V_{Rd}, is taken as the resistance of the structural steel section, V_{pl,a,Rd}. The contribution of the concrete slab is neglected in this calculation.
The shear check is performed in accordance with EC3, 6.2.6.
Moment capacity
For full shear connection the plastic resistance moment is determined in accordance with clause 6.2.1.2. For the partial shear connection clause 6.2.1.3 is adopted.
In these calculations the steel section is idealized to one without a root radius so that the position of the plastic neutral axis of the composite section can be determined correctly as it moves from the flange into the web.
Where the vertical shear force, V_{Ed}, exceeds half the shear resistance, V_{Rd}, a (1 ρ) factor is applied to reduce the design strength of the web  as per clause 6.2.2.4.
Shear capacity (Longitudinal)
The design condition to be checked is: v_{Ed} ≤ v_{Rd} where:
v_{Ed} = design longitudinal shear stress
v_{Rd} = design longitudinal shear strength (resistance)
v_{Ed} is evaluated at all relevant locations along the beam and the maximum value adopted.
v_{Rd} is evaluated taking account of the deck continuity, its orientation and the provided reinforcement.
This approach uses the “truss analogy” from EC2. (See Figure 6.7 of EC2).
In these calculations, two planes are assumed for an internal beam, and one for an edge beam. Only the concrete above the deck is used in the calculations.
The values of v_{Rd} based on the concrete “strut” and the reinforcement “tie” are calculated. The final value of v_{Rd} adopted is then taken as the minimum of these two values.
The angle of the strut is minimised to minimise the required amount of reinforcement  this angle must lie between 26.5 and 45 degrees.
In the calculations of v_{Rd} the areas used for the reinforcement are as shown in the following table.
Decking angle  Reinforcement type  Area used 

perpendicular  transverse  that of the single bars defined or for mesh the area of the main wires^{[1]} 
other  that of the single bars defined or for mesh the area of the main wires^{[1]}  
parallel  transverse  that of the single bars defined or for mesh the area of the main wires^{[1]} 
other  single bars have no contribution, for mesh the area of the minor wires^{[2]} 
^{[1]}These are the bars that are referred to as longitudinal wires in BS 4483: 1998 Table 1.
^{[2]}These are the bars that are referred to as transverse wires in BS 4483: 1998 Table 1.
If the decking spans at some intermediate angle (θ_{r}) between these two extremes then the program calculates:

the longitudinal shear resistance as if the sheeting were perpendicular, v_{Rd,perp},

the longitudinal shear resistance as if the sheeting were parallel, v_{Rd,par},

then the modified longitudinal shear resistance is calculated from these using the relationship, v_{Rd,perp}sin^{2}(θ_{r}) + v_{Rd,par}cos^{2}(θ_{r}).