Analysis of self stressed studded sandwich bridge decks

A new type bridge deck consisting of an unreinforced lightweight concrete slab made of expanding cement sandwiched between two thin steel plates is investigated from a structural behavior point-of-view. Of primary interest are the advantages to be gained from the expansive cement induced membrane tensile forces in the face plates, precompression of the core, and increased frictional resistance between the concrete and steel to enhance the composite behavior of the sandwich plate.

A discussion is given on the results of laboratory experiments to determine the nature of self-induced pressures and expansions of specimens subject to uniaxial restraints. Tests to measure the moduli of elasticity of various expanding concretes under autogeneous condition of curing are also described. The results of experimental investigations to determine the flexural behavior of twelve sandwich panels, loaded with either concentrated or uniformly distributed forces, are presented.

An analytical method is developed to predict the prestressing forces that are induced in the steel and concrete components of the sandwich panel under the influence of the expanding core. Governing differential equations for the flexural behavior of an externally loaded sandwich panel subject to slippage at the steel-concrete interfaces are derived for a four layer system made up of the outer face plates and the concrete compression and tension elements.

A comparison of the theoretical and analytical results is presented. Primary findings indicate that the sandwich plate behaves as a composite structure with significant slippage at the interfaces and that the amount of prestressing obtained is insignificant.

A comparative study of the proposed sandwich plate and a standard reinforced concrete slab is also made and a set of conclusions on the basic findings and recommendations for further studies are given.