Putting steel into glazing
Steel Supported Glazing Systems1 is a straightforward introduction to the types of systems comprising glazed panels bolted to supporting steel framing. Pilkington’s Planar system is the best-known proprietary example, though here systems are treated generically to provide an overview of current options.
The first three chapters cover the range of available glazing panels, types of bolted fixings and types of support structures. Less familiar will be the details of performance in the design chapter:
the tolerances typical of the factory and site
movement in-plane (eg thermal) and out-of-plane (eg wind) of glass panels, of the supporting structure and the building frame
loading, including the support of maintenance personnel
durability - typical sealant or gasket life is claimed to be 25-40 years.
The interface of most concern here is the ‘glazing support attachment’ - the component between the bolt fixing to the glass and the supporting frame. The main options are angle brackets, spiders, pin brackets and clamps. Performance is discussed assuming these are available components - there is nothing on specials such as specifying spider castings.
The publication finishes with case studies of the glazing systems at Waterloo International station (Grimshaw/Anthony Hunt), Proctor and Gamble at Brooklands (Aukett/Hunt), the Glass Hall, Neue Messe Leipzig (Vongerkan Marg/Ian Ritchie) and Bridgewater Hall, Manchester (rhwl/W S Atkins). These focus again on system configuration and details.
Both these case studies and the main text could usefully have gone beyond this focus to look too at processes - procurement, testing and site assembly. Nor is there a sense of future trends. Within these limitations, the publication provides a clear structure for understanding the current range of systems, which may be familiar from pictures but less well understood as a technology.
If the glazing-systems publication works as a straightforward primer, Design of Steel Framed Buildings for Services Integration2 is both more complicated and less informative. Structure-services integration is a good subject, of wide interest. But the publication gets bogged down in a lot of detail of services not much relevant to integration and long descriptions of familiar beam options. (There is some useful detail, such as on permissible sizes of web openings, spanning limitations and the like.)
The publication also reduces the broad promise of its title to a discussion of minimising the height of buildings of 12-15m span framed with steel beams in composite floor construction. Integration here may occur between the beam and horizontal air-trunking zones. Perforate beam systems allow some sizes of trunking to cross the principal span within their structural depth rather than having to pass beneath - beams with web openings, parallel beam systems, haunched-end beams, fabricated tapered beams, stub-girder beams and composite trusses.
A case study of one 15m-deep office building compares these beam options with a more traditional composite beam and slab system of two 7.5m spans. With that the ducting must pass beneath the beams, adding to building height and thus to cost in its own way. The publication concludes that, compared with the two 7.5m spans, clear 15m spans can be achieved for a small net extra whole-building cost in the range of £1-15/m2. This is for an £850/m2 total building cost, of which £118/m2 is for foundations and structure.
This is a result of some interest. It could have been more useful if this publication had looked at more cases in less detail, to give designers more sense of the pattern of options. And the ritual sideswipe at concrete framing serves to remind us that what designers need more is a balanced publication on the steel and concrete options.
1 Steel Supported Glazing Options. P Ryan, M Otlet and R G Ogden. Steel Construction Institute, tel: 01344 623345. Publication SCI 193. 73pp. £35.00.
2 Design of Steel Framed Buildings for Services Integration. P D McKenna and R M Lawson. Steel Construction Institute, tel 01344 623345. Publication SCI 166. 107pp. £40.