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As previously described, in the shear connectors area there are 3 options available.
1. Usually the number of studs per trough for a secondary beam is selected from the list. The capacity of the studs arrangement is then calculated as per the selected design code. For a primary beam the spacing of the studs can be set and whether these are single studs or a pair of studs. The 'As Welded Height' of the stud can be entered in mm. The British Standard asks for the stud height to be at least 35mm above the top of the troughs in the decking, whereas the EuroCode asks for this dimension to be 2 x dia of the stud, eg, 38mm for a 19mm stud.
2. There is also an option for a raised rib pattern on the top flange surface which is usually found on Asymmetrical Slimfloor Beams (ASBs) in a slimfloor construction situation. In this case the raised rib pattern is transferring some of the load from the beam to the concrete in place of studs.
3. The design can also be set so that the beam is considered as Non-Composite (NC). It is often the case that a short span edge beam is more efficient as a steel beam than a composite beam as not enough studs can be welded in place to transfer a share of the load from the beam into the concrete.
Design of the shear connectors - increase or decrease the number of studs per trough in a secondary beam or the stud spacing in a primary beam until the Shear Connection is satisfied. The stud diameter and as-welded height can be changed too, if necessary.
Additional Options - when the number of shear studs are specified it is often possible to add an additional stud at the start or end of a run. Hence there is an option on the Defaults tab for increasing the number of shear connectors by 1. For example, if the studs in a 7.1m long primary beam are spaced at a given spacing, say 200mm centres, you could have 35 or 36 studs depending exactly where the first stud is placed. This option gives the user control over the number used in the design.
When holes are provided in the sheeting for the placement of the studs, the contribution of the sheeting to the transverse reinforcement is negated and so more reinforcement area may be required. This option is also available on the Defaults tab.
The degree of shear connection in composite design has seen much work carried out, particularly by the SCI, to improve the design methods used in both BS and EC design. Options are provided to include this work in the design of the shear connection. These are SCI AD 148 for minimum shear connection in BS design and SCI P405 Minimum Degree of Shear Connection to EC4, NCCI PN001a-GB Resistance of Headed stud shear connectors in transverse sheeting and NCCI PN002a-GB Modified Limitation on Partial Shear Connection. These options are also available on the Defaults tab.
The area of transverse shear reinforcement can be defined. You can either select a mesh area from the droplist or overtype it with your own area of reinforcement. This could be an area of bars placed over a metre length (of the beam span) instead of mesh, eg, T16s at 300mm c/c (670mm2). There are 2 boxes for mesh - usually the top 'Mesh (mm2)' value is the area of global mesh which applies across the full floor and the 'Add. Mesh' which is an area of additional mesh to be located locally for the particular beam you are working on. The position of the mesh can be specified as either above the head of the studs or to be more than 10mm below the head. This can have an effect on the transverse reinforcement requirements.
Design of the Shear Reinforcement - add an area of reinforcement to either the Mesh or to the Additional Mesh boxes until the Transverse Shear is satisfied.
The number of shear connectors and the area of transverse shear reinforcement are linked. If the number of shear connectors is increased then the concrete slab has to be able to take more shear through its cross-section from these additional studs. This may mean an increase in the area of reinforcement required to help resist the shear. Alternatively, the concrete compression within the slab could be the governing factor meaning the concrete grade or the slab thickness needs to be increased so as to provide more concrete capacity.