ARCH205 BUILDING CONSTRUCTION

FLOOR & ROOF SYSTEMS

FLOOR SYSTEM

• Floor systems are the horizontal planes that must

support both:

• live loads—people, furnishings, and movable equipment

• dead loads—the weight of the floor construction itself.

• Floor systems must transfer their loads horizontally

across space to either beams and columns or to

loadbearing walls.

CONCRETE BEAM

38mm minimum cover required to protect steel reinforcement from fire and corrosion.

Effective

Beam Depth

Beam Depth Concrete beam depth = span/16

Beam width Bevel or

Chamfer

CONCRETE FLOOR SLAB TYPES

• One-Way Slab

• A one-way slab is

uniformly thick,

reinforced in one

direction, and cast

integrally with parallel

supporting beams.

• Suitable for light to

moderate loads over

relatively short spans of

(1.8 to 5.5 m)

CONCRETE FLOOR SLAB TYPES

• One-Way Joist Slab

• A joist or ribbed slab is cast

integrally with a series of closely

spaced joists, which in turn are

supported by a parallel set of

beams.

• Designed as a series of T-

beams, joist slabs are more

suitable for longer spans and

heavier loads than one-way

slabs. • Suitable for light to medium live loads

over spans of (4 to 10 m)

CONCRETE FLOOR SLAB TYPES

• Two-Way Slab and Beam

• A two-way slab of uniform

thickness may be reinforced

in two directions and cast

integrally with supporting

beams and columns on all

four sides of square or

nearly square bays.

• 100 minimum slab depth.

• suitable for carrying intermediate

to heavy loads over (4.6 to 12 m)

spans.

CONCRETE FLOOR SLAB TYPES

• Two-Way Waffle Slab

• A waffle slab is a two-way

concrete slab reinforced by

ribs in two directions.

• Waffle slabs are able to

carry heavier loads and

span longer distances than

flat slabs.

• Suitable for spans of (7 to 16

m) (75 to 115) slab depth

(125 or 150) rib width

CONCRETE FLOOR SLAB TYPES

• Two-Way Flat Plate

• A flat plate is a concrete slab of

uniform thickness reinforced in two

or more directions and supported directly by columns without beams

or girders.

• Simplicity of forming, lower floor-to-

floor heights, and some flexibility in column placement make flat

plates practical for apartment and

hotel construction.

• Suitable for light live to moderate loads over relatively short spans of

(3.6 to 7 m)

CONCRETE FLOOR SLAB TYPES

• Two-Way Flat Slab

• A flat slab is a flat plate thickened at its column

supports to increase its shear strength and moment-

resisting capacity. Suitable for relatively heavy loads

and spans from (6 to 12 m).

CONCRETE SLAB FORMWORK AND SHORING

Wood shores

Support for

Beam

Formwork

Adjustable

Wood/Metal

shores

Bracing on

shores

Knee brace

Kickers

Blocking

Plywood/metal

sheathing

Metal/wood joists Stringers

FLYING FORMS

• Flying forms are large sections of formwork,

including supporting trusses, beams, or scaffolding,

that can be moved by a crane in constructing the

concrete floors and roofs of multistory buildings.

LIFT-SLAB CONSTRUCTION

• Lift-slab construction is a technique of constructing

multistory buildings in which all horizontal slabs are

cast at ground level and, when cured, are raised

into position by hydraulic jacks.

STRUCTURAL STEEL FLOOR

• One way beam system

• Typical span range for beams is (6 to 10 m).

Columns

Girders

Beams

STRUCTURAL STEEL FLOOR

• Two-Way Beam System

Columns

Primary Beams

Secondary Beams

OPEN-WEB JOISTS

• Open-web joists are lightweight, shop-fabricated

steel members having a trussed web.

Passage of mechanical

services through the open

web

Ceiling can be either

attached to the bottom of

the joist or suspended or left

without ceiling.