The Effects of Camber in Steel Slabs
- The building designer requests metal slabs that are specifically fabricated with a camber. The designer and contractor need this deflection due to the prospective weight that will be placed on the slabs. Steel slabs that do not possess any camber may bow in time due to the sheer weight -- dead load -- applied to them. The dead load creates a dip in the floor and stress on supporting frames. This dead load may consist of concrete flooring, barriers and utilities. When the manufacturer creates the cambered steel and the contractor installs the slab, the weight placed on top slowly decreases the deflection of the steel slab, creating a level floor.
- Contractors use steel decks to support concrete flooring. The contractor creates a composite slab consisting of steel beams and concrete that has been hardened. The designer must base the amount of deflection required on whether to use a post-tensioned or reinforced floor system. Factors to consider involve the length of the slab, concrete strength and how much steel reinforcement is used. The designer requests anywhere from 1/2 inch or more of fabricated camber if predicting excessive loads on the flooring.
- The designer and contractor decide on the camber of composite steel and concrete slabs based on three types of dead loads. Dead load construction of the deck slab has to do with the entire weight of the deck slab flooring. Added dead load deflection deals with the amount of weight from barriers, sound walls and overlays that's added at a future time. Calculating dead load deflection of the steel girder involves consideration of the weight of the girders, cross frames and other attachments during initial construction.
- Most construction consists of unshored composite methods used due to the expense. This method involves adding the camber to deal with the added weight. Yet shored construction that uses less camber for the structural steel slabs may also be used by the contractor. This procedure uses movable supports that are later removed after the concrete achieves the desired strength. Shored construction has risks involving the development of cracks along the concrete once the supports are removed.