CHAPTER 2: SUPER-STRUCTURE LECTURE LECTURE LECTURE LECTURE
1 2 3 4
– REINFORCEMENT FRAMES - COLUMN AND BEAM - FLOORING - ROOF
LECTURE 3 FLOORING
FLOORING System Basically divided into two (2) systems: - one-way spanning slab - two-way spanning slab one-way spanning slab
two-way spanning slab
FLOORING One Way Spanning Slab
R.c slab and beams system with beams spanning in one direction on rectangular grid.
For small span and lightly loaded structures
If beams are sufficiently deep, internal columns may be omitted, giving wider unobstructed usage of floor area.
FLOORING
FLOORING Two Way Spanning Slab
R.c slab and beam system with beams spanning in 2 directions forming square grids.
Resulting in reduction in thickness and dead weight of slab
For large spans and heavy loaded structure
FLOORING
FLOORING Types ď ľ
Divided into three (3) types: 1. Flat Plate Floor 2. Flat Slab Floor 3. Waffle Slab
FLOORING 1. Flat Plate Floor
FLOORING 1. Flat Plate Floor
R.c floor slab resting directly on reinforced concrete columns with no projecting beams. It is a monolithic system. Most efficient for light and medium loading as in flats and offices. Reinforced on the upper side of slab, on all directions covering whole floor surface with emphasis along column grids. Regular spacing of columns – approximately 5.5 m (18 ft.) on both directions are more economical. For domestic loading – grid spacing of 3m (15 ft) with plate thickness of 150 mm. For a span of 3.5 m, plate thickness of 200 mm
FLOORING 1. Flat Plate Floor
Advantages: simplification of formwork Reduction in dead weight Flat soffit – able to use standard height partition. Possible reduction in floor height, therefore, overall reduction in building height.
Disadvantages: Only suitable for lightweight structures
FLOORING 2. Flat Slab Floor
FLOORING 2. Flat Slab Floor
Another form of r.c floor without projecting beams
Termed as mushroom construction because of the expanded column heads.
Sometimes necessary to thicken the slab over column cap to form a drop panel
Suitable for heavy loading e.g. warehouses
Simpler formwork and possible reduction of floor height but floor thickness is increased
Max. efficiency – columns must be in regular grid 6 – 7.5 m, slab thickness 225 – 300 mm.
FLOORING 2. Flat Slab Floor
Advantages: Formwork is simple and economical Saving in storey height. Better lighting facilities due to flat ceiling Structurally economical Good appearance due to flat ceiling
Disadvantages: Need to thicken slab for heavier loads
FLOORING 3. Waffle Slab Floor
FLOORING 3. Waffle Slab Floor
FLOORING 3. Waffle Slab Floor
A two way r.c ribbed floor with a thin slab.
Floor is cast over moulds made of fiber glass or steel
Waffle pattern can add to the visual aspect of ceiling
Advantages: Suitable for wide spans Dead weight is reduced as hollow block replaces portion of solid concrete thereby more economical
Disadvantages: More restriction to installation of services Careful supervision required when constructing
END OF LECTURE 3 – CHAPTER 2