Exodermic Bridge Deck s For Bridge Deck Replacement f4g4u

Exodermic bridge deck s for bridge deck replacement A system which has been in use since the 1930s in the USA is the Exodermic bridg e (Bettigole 2000) and is now installed on 40 bridges in the USA. It consists of a lightweight (245 kg/m2) open steel grid upon which is laid galvanized steel sheets which act as shuttering for a reinforced concrete slab up to a maximum of 115 mm thick, and i t is able to span up to 4.4 m (see Figure 8.16). By virtue of its lightweight (usually lighter than the deck it is replacing) it allows for an increase in live load. The steel grid and the concrete act as a composite sec tion, and it is claimed that the s can resist both positive (sagging) and negative (hogg ing) bending. The s themselves are made composite with the bridge by welding she ar studs to the top of the steelwork through blockouts in the Exodermic s, aft er which rapid hardening concrete is poured. Once the whole deck is completed, the surfac e of the concrete is diamond ground for a smooth riding surface, and overlaid with a 9.5mm epoxy concrete riding surface (Bettigole 2000). Rapid replacement is possible, often working overnight to minimize traffic disru ption, and the work progresses in bays so that at the end of each working day there is a transverse construction t across the bridge (the new abutting the old). This has the ad vantage that all lanes can be opened in the early mornings, and the only discomfort for drive rs is the slight bump as vehicles travel over the t. The design of the s was revised in the early 1990s to improve the means of shear connection and to simplify some of the details to reduce fabrication costs. The new design has been thoroughly tested under both static and dynamic loads and continues to perform well.