Ribbed Floor Slab Design

Ribbed and waffle slabs.

Ribbed floor slab design. Ribbed slabs are made up of wide band beams running between columns with narrow. The slab is the flange of the beam and the extended part is the web. The cores can function as service ducts and significantly reduce the self weight of the slabs maximizing structural efficiency. Ribbed slabs one way joists introducing voids to the soffit of a slab reduces dead weight and increases the efficiency of the concrete section.

Sandwich slabs may have the disadvantage of a larger weight compared to the ribbed ones but on the other hand they have the advantage that their spans and supports behave in the same proper way. The extended part is known as ribs. The slab has to carry a distributed permanent action of 1 0 kn m2 excluding slab self weight and a variable action of 3. Simply supported one way slab a rectangular reinforced concrete slab is simply supported on two masonry walls 250 mm thick and 3 75 m apart.

Design of two way slabs example 1 2 use i wsd ii usd to design the two way slab shown below carrying floor finish 30 psf random wall 50 psf and live load 60 psf given. These types of slabs are used in constructing floors of multi storeyed building. Economic in the range 8 to 12 m. Design of slab examples and tutorials by sharifah maszura syed mohsin example 1.

F c 3 ksi f y. The spacing between the ribs should be in general 20 30 inch. Ribbed or waffle slab is a slab system which consists of series of parallel reinforced concrete t beams framing into reinforced concrete girders. Watch design details of ribbed slab waffle slab in prota structure.

Ribbed and waffle slabs provide a lighter and stiffer slab than an equivalent flat slab reducing the extent of foundations. Design the floor to satisfy ultimate and serviceability limit state requirements. Ribbed waffle slab system. Hollow core ribbed slab or hollow core slab hollowcore ribbed slabs derive their name from the voids or cores which run through the units.

Sandwich slab reinforcement details in reality sandwich slabs are ribbed slabs with a slab placed both to their upper and lower surface. A slightly deeper section is required but these stiffer floors facilitate longer spans and provision of holes. They provide a very good form of construction where slab vibration is an issue such as laboratories and hospitals. This form of construction is not very common because of the formwork costs and the low fire rating.

The saving of materials tends to be offset by some.