# Shear connectors (ULS) (Composite beams: EC4 Eurocode)

## Dimensional requirements

Various limitations on the use of studs are given in the code.

The following conditions in particular are drawn to your attention:

Parameter | Rule | Clause/Comment |
---|---|---|

Spacing |
Ductile connectors may be spaced uniformly over length between critical cross-sections if: - All critical cross-sections are Class 1 or 2 - The degree of shear connection, h is within the range given by 6.6.1.2 and - the plastic resistance moment of the composite section does not exceed 2.5 times the plastic resistance moment of the steel member alone. |
6.6.1.3(3) - not checked |

Edge Distance | e_{D} ≥ 20 mm |
6.6.5.6(2) - not checked |

e_{D} ≤ 9 *
t_{f}*sqrt(235/f_{y}) |
6.6.5.5(2) - applies if bare steel beam flange is Class 3 or 4 - not checked | |

Location | If it cannot be located in the center of trough, place alternately either side of the trough throughout the span | 6.6.5.8(3) - not checked |

Cover | The value from EC2 Table 4.4 less 5mm, or 20mm whichever is the greater. | 6.6.5.2(2) - not checked |

The program does not check that the calculated stud layout can be fitted in the rib of the deck.

## Design resistance of the shear connectors

For ribs parallel to the beam the
design resistance is determined in accordance with clause 6.6.4.1. The reduction
factor, k_{l} is obtained from Equation 6.22. For ribs perpendicular to the
beam, clause 6.6.4.2 is adopted.

The reduction factor, k_{t} is obtained from Equation 6.23.

The factor k_{t} should not be taken greater than the appropriate value of
k_{t,max} from the following table:

No of stud connectors per rib |
Thickness of sheet, t mm |
Studs with ≤ 20 mm and welded through profiled steel
sheeting, k_{t,max} |
Profiled sheeting with holes and studs with d = 19 or 22 mm,
k_{t},max |
---|---|---|---|

n_{r} = 1 |
≤ 1.0 | 0.85 | 0.75 |

> 1.0 | 1.00 | 0.75 | |

n_{r} = 2 |
≤ 1.0 | 0.70 | 0.60 |

> 1.0 | 0.80 | 0.60 |

_{t.max}is used from the above table since the technique of leaving holes in the deck so that studs can be welded directly to the beam is not used.

For cases where the ribs run at an
angle, θ_{r} the reduction factor is calculated as:

k_{t} * sin^{2} θ_{r} + k_{l} *
cos^{2}θ_{r}

Stud optimization is a useful facility since there is often some over conservatism in a design due to the discrete changes in the size of the section.

If you choose the option to optimize the shear studs, then Tekla Structural Designer will progressively reduce the number of studs either until the minimum number of studs to resist the applied moment is found, until the minimum allowable interaction ratio is reached or until the minimum spacing requirements are reached. This results in partial shear connection.

The program can also automatically layout groups of 1 or 2 studs with constraints that you specify.

The degree of shear connection is checked at the point of maximum bending moment or the position of a point load if at that position the maximum utilization ratio occurs.

To determine if the degree of shear connection is acceptable Tekla Structural Designer applies the following rules:

- If the degree of shear connection at the point of maximum moment is less than the minimum permissible shear connection, then this generates a FAIL status,
- If the point of maximum utilization ratio occurs at a point that is not the maximum moment position and the degree of shear connection is less than the minimum permissible shear connection, then this generates a WARNING status,
- If the degree of shear connection at any other point load is less than the minimum permissible shear connection, then this does not affect the status in any way.