AD 420: Minimum values of shear and bending moment in beams with web openings
Table 3.1 of SCI publication P355 gives minimum values of co-existent shear and bending moment to be used at beam openings. This AD provides clarity on how these minimum values are to be used.
The concern behind the minimum values was to allow for non-uniform loading, to guard against the situation when the shear force at an opening could theoretically be zero. Table 3.1 therefore includes minimum values of the shear force to be allowed for in design. The minimum values of shear force in Table 3.1 have an associated bending moment.
The intention was that the minimum shear force and associated bending moment from Table 3.1 should only be applied if the theoretical shear at an opening was less than the minimum quoted. There is no requirement to apply the minimum bending moment at all openings – the minimum bending moment should only be applied if the minimum shear force is used in design.
Contact: Prof Mark Lawson
Tel: 01344 636555