Design method (Composite beams: BS 5950)

Unless explicitly stated all calculations are in accordance with the relevant sections of BS 5950-3.1:1990+A1:2010 (Ref. 1). You may find the handbook and commentary to the Code of Practice published by the Steel Construction Institute (Ref. 3 and 4) useful.

Construction stage design checks

When you use Tekla Structural Designer to design or check a beam for the construction stage (the beam is acting alone before composite action is achieved) the following conditions are examined in accordance with BS 5950-1:2000:

section classification (Clause 3.5.2),
shear capacity (Clause 4.2.3),
moment capacity:
- Clause 4.2.5.2 for the low shear condition,
- Clause 4.2.5.3 for the high shear condition,
- lateral torsional buckling resistance (Clause 4.3.6),
  
  Note: This condition is only checked in those cases where the profile decking or precast concrete slab (at your request) does not provide adequate restraint to the beam.
web openings,
Westok checks,
- Shear horizontal,
- Web post buckling,
- Vierendeel bending,
construction stage total load deflection check.

Composite stage design checks

When you use Tekla Structural Designer to design or check a beam for the composite stage (the beam and concrete act together, with shear interaction being achieved by appropriate shear connectors) the following Ultimate Limit State and Serviceability Limit State conditions are examined in accordance with BS 5950 : Part 3 : Section 3.1 : 1990 (unless specifically noted otherwise).

Ultimate limit state checks

section classification (Clause 4.5.2), depending on whether adequate connection is achieved between the compression flange and the slab. The section classification allows for the improvement of the classification of the section if the appropriate conditions are met,
vertical shear capacity (BS 5950-1:2000 - Clause 4.2.3),
longitudinal shear capacity (Clause 5.6) allowing for the profiled metal decking, transverse reinforcement and other reinforcement which has been defined,
number of shear connectors required (Clause 5.4.7) between the point of maximum moment and the end of the beam, or from and between the positions of significant point loads,
moment capacity:
- Clause 4.4.2 for the low shear condition,
- Clause 5.3.4 for the high shear condition,
web openings.

Serviceability limit state checks

service stresses (Clause 6.2),
- concrete
- steel top flange and bottom flange
deflections (Clause 6.1.2)
- self-weight
- SLAB loadcase,
- dead load,
- imposed load^[1],
- total deflections,
natural frequency check (Clause 6.4).

^[1] This is the only limit given in BS 5950 : Part 3 : Section 3.1 : 1990.