Precast open sandwich panels for bridge decks

Precast open sandwich panels for bridge decks 

Conventional bar reinforcement is advised for incorporation in the top surface of open sandwich decks to control cracking and to provide continuity. Tensile stresses will occur in the transverse 

A flexibilised cold-curing epoxide adhesive containing an aromatic amine hardener is likely to be the most successful, particularly if 

Transverse continuity may be provided by using an in situ concrete connection containing looped reinforcement cast into the slabs (Fig. 8.3) an alternative arrangement using folded steel plates may also be used (Fig. 8.4). The primary shear connection is provided by shear studs welded alternately to the soffit plate and the longitudinal beam flange. It is important that the precast/i situ construction joint occurs well away from the beam flange to avoid excessive rotations and subsequent slab distress under traffic loads. 

The possibilities for making bonded structural sandwich elements in a variety of materials are very real. However, whilst there exist structural examples such as aluminium honeycomb panels (used in aircraft and transport applications) and metal skinned foam sandwich panels (used as the monocoque chassis in refrigerated transport applications), these composite constructions are normally utilised in non- or semi-structural ways. Typical skin materials are steel, aluminium, GRP and plywood, and common core materials are rigid foam polystyrene, polyurethane, polyisocyanurate, PVC, and honeycombed aluminium. In some instances the foam core is injected between the skins and adheres to them in others, adhesives are used to bond the separate components together. The nature of the manufaeturing process depends on the type of structure to be made, and the degree of investment in produetion maehinery. Both flat and eomplex eurved forms ean be made by a hand lay-up process as well as in an automated way. 

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