Ribbed construction

Single-skin construction can be stiffened by a system of ribs on the back of the panel, such as those at Mondial House, London (Fig. 3.16). Ribs are normally made from GRR laminated over a rib former in a mould, but they can also be formed by incorporating another

3.13 Corner panels at Winwick Quay (architects: Nicholas Grimshaw Partnership).

material of appropriate shape and stiffness into the panel. Polyurethane foam or cardboard tubes can be used as rib formers. Where timber or metal sections are laminated into, or over-laminated onto, the back of the GRP skins, these materials have different coefficients of thermal expansion from that of the GRP and it may be necessary to ensure a mechanical key grip rather

GRP connector

Fngmed polyethylene cors

3.14 Methods of stiffening GRP panels: (a) shaped profile; (b) ribbed construction; (c) sandwich construction using GRP connector and foamed insulation core; (d) sandwich construction - stiff insulation sheet laid into lamination.

3.14 Methods of stiffening GRP panels: (a) shaped profile; (b) ribbed construction; (c) sandwich construction using GRP connector and foamed insulation core; (d) sandwich construction - stiff insulation sheet laid into lamination.

than rely upon adhesion. Aluminium sections are particularly useful, because they have similar properties to GRP with regard to thermal expansion.

Rib patterning/shadowing on the face of the panel has also been known to occur, and some manufacturers have found that to overcome this the top-hat section or rib should be vented by cutting during the fabrication process (Fig. 3.9).This results in an even balance of temperature over the total face

3.15 Section through GRP panels at American Express building, Brighton (architects: Collins MelvinWard Partnership).

area of the panel when heat build-up occurs, either during curing or on site due to direct sunlight.

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