A Highways Agency Category 3 structure could be one with a span in excess of 50m, a skew of more than 45°, or simply one with difficult foundations.
Category 3 structures also include 'complex structures which require sophisticated analysis' and those with 'unconventional, novel or esoteric design aspects.' Waterman anaging director Bob Campbell says 'innovative structures' include those which incorporate new or novel materials.
'Complex ructures' would be those with no regular rectilinear grid or vertical supporting members.
They could also have abnormally long cantilevered members, or be subject to significant lateral forces.
Campbell says 'unusual structures' would include those higher than 75m or with spans greater than 25m for floors and 40m for roofs.
High occupancy buildings would also fall into this category.
Structural onsultant Professor Jonathan Wood suggests that projects incorporating elements not explicitly covered by codes of practice or industry guides should be subject to independent checks.
l How would you defi ne structures that should have independent third party checks- Email your suggestions to NCE technical editor Dave Parker on dave.parker@emap. com