Determine the optimum number of shear connectors for composite beams

Did you know that you could use Consteel to determine the optimum number of shear connectors for composite beams?

In composite beam design, the required number of shear studs is not only a detailing issue but a direct part of the structural resistance mechanism. The modelling and design environment in Consteel allows this number to be determined in a rational and automated way, consistent with EN 1994-1-1:2010.

The process begins with the definition of a composite beam cross-section (Macro section). Two standard types are available: a solid slab composite beam and a profiled steel sheeting composite beam. The effective width is defined at input level, but the actual effective width used in analysis is calculated automatically based on span, geometry, and stud spacing assumptions. This ensures that the structural response is captured realistically, while maintaining simple input control for the user.

After defining the cross-section, the member is created and design parameters are assigned through object properties. These parameters govern key aspects of composite behaviour, including stud spacing, support conditions, and whether shear stud design is performed manually or automatically.

For shear connector design, Consteel applies a plastic distribution model. The governing section of the beam, typically corresponding to the maximum bending moment, is identified automatically. From this section, shear studs are distributed symmetrically along the beam length.

When automatic optimisation is selected, the software determines the minimum number of shear studs required to satisfy bending resistance. It then increases the number iteratively until the composite section achieves sufficient capacity. The resulting value represents the optimal number of shear connector positions for the given loading and geometry.

The key parameters used in this evaluation include:

• nopt: optimal number of shear stud positions in the governing region
• nact: actual number of stud positions applied
• sL, sR: spacing of studs on the left and right side of the critical section
• nmin: minimum required number of stud positions based on resistance

The ratio nact / nopt is used as a direct measure of utilisation of the shear connector system.

There is also the option to define the number of studs manually. In that case, Consteel distributes them uniformly along the member and checks compliance with detailing rules such as minimum and maximum spacing. This is typically useful when construction constraints or predefined detailing standards take priority.

Composite beam design itself is carried out according to EN 1994-1-1:2010. Plastic bending resistance is evaluated for Class 1 and 2 cross-sections, while shear, concrete flange crushing, and longitudinal shear are checked at critical sections. Shear buckling is treated according to EN 1993-1-5. Lateral-torsional buckling is not included in the current design scope.

For profiled sheeting, shear stud resistance is reduced depending on rib orientation, in line with Eurocode 4 rules.

Overall, the key point is that the number of shear connectors is no longer an assumed input. It is derived from structural demand through an automated and transparent process, which makes it easier to reach an efficient and consistent composite design without repeated manual iteration.

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