We wish to question the necessity and advantage of wire reinforcing mesh being used in 2-inch to 4-inch topping over prestressed twin T beams. (I ) Does the topping increase the load carrying ability of the beams? (2) Does sire reinforcing mesh increase the load carrying ability of the beams significantly over unreinforced topping? (3) Is it practical economically to use it in topping over beams?
(I) Yes, if bonded to the slab. A good bond can be achieved if the surface of the slab is reasonably rough and clean from loose materials at the time of placing. A bonded topping increases the effective depth of the section which, in turn, increases the moment capacity. (2) Not for vertical loads, since the topping is under compression for simply supported members. However, welded wire fabric should be used to allow the topping to carry horizontal loads (diaphragm) when necessary for the lateral stability of the building. Welded wire fabric can also control shrinkage and temperature cracking, especially at the joints between adjacent slabs. (3) The economics of using welded wire fabric should be evaluated only for individual cases, taking into account the specific architectural and structural requirements of the building.