1. Arch205 Material and building construction 1 floor & Roof systems

2. 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.

3. Concrete beam Effective Beam Depth
38mm minimum cover required to protect steel reinforcement from fire and corrosion.
Beam Depth
Concrete beam depth = span/16
Bevel or Chamfer
Beam width

4. 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)

5. 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)

6. 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.

7. 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

8. 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)

9. 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).

10. Concrete slab formwork and Shoring
Knee brace
Plywood/metal sheathing
Blocking
Kickers
Metal/wood joists
Stringers
Support for Beam Formwork
Adjustable Wood/Metal shores
Wood shores
Bracing on shores

11. 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.

12. 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.

13. Structural steel floor
One way beam system
Typical span range for beams is (6 to 10 m).
Beams
Girders
Columns

14. Structural steel floor
Two-Way Beam System
Secondary Beams
Primary Beams
Columns

15. Open-web joists
Open-web joists are lightweight, shop-fabricated steel members having a trussed web.
Ceiling can be either attached to the bottom of the joist or suspended or left without ceiling.
Passage of mechanical services through the open web

16. Roof system
The roof system functions as the primary sheltering element for the interior spaces of a building.
The construction of a roof should also control the passage of moisture vapor, the infiltration of air, and the flow of heat and solar radiation.
The roof structure and assembly may have to resist the spread of fire.
The form of a roof structure—whether flat or pitched, gabled or hipped, broad and sheltering, or rhythmically articulated—has a major impact on the image of a building.

17. Roof types
Flat roofs require a continuous membrane roofing material. Minimum recommended slope: 1:50.
Reinforced Concrete Slab
Flat Timber or Steel Truss
Timber or Steel Beams and Decking
Wood or Steel Joists and Sheathing

18. Sloping roofs may be categorized into
• Low-slope roofs—up to 3:12
• Medium- to high-slope roofs—4:12 to 12:12
Sloping roofs shed rainwater easily to eave gutters.
Wood or steel rafters and sheathing.
Timber or steel beams, purlins, and decking.
Timber or steel trusses.

19. Concrete roof slab
Details of concrete roof slabs are similar to that of concrete floor slabs.
Section showing layers of concrete roof slab:

20. Edge treatment of roof slab
An upturned edge beam can form a
parapet wall.
The slab can be cantilevered beyond its
perimeter supports to form an overhang.
An edge or spandrel beam can support
a nonbearing curtain wall.
Metal anchors may be cast into the
spandrel beams to secure the curtain
wall panels.

21. Reinforced concrete may be designed and cast into a variety of other roof forms, such as folded plates, domes, and shell structures.

22. Steel trusses Flat trusses have parallel top and bottom chords.
Flat trusses are generally not as efficient as pitched or bowstring trusses.
Pratt trusses have vertical web members in compression and diagonal web members in tension.

23. Howe trusses have vertical web members in tension and diagonal web members in compression.
Belgian trusses have only inclined web members.
Fink trusses are Belgian trusses having subdiagonals to
reduce the length of compression web members toward the centerline of the span.

24. Warren trusses have inclined web members forming a series
of equilateral triangles.
Bowstring trusses have a curved top chord meeting a
straight bottom chord at each end.
Raised-chord trusses have a bottom chord raised
substantially above the level of the supports.
Scissors trusses have tension members extending from
the foot of each top chord to an intermediate point on the
opposite top chord.

25. Steel trusses Members are bolted or welded with gusset roof decking
plate connectors.
roof decking
Channel or W-shape purlins
Steel bearing plate
lateral bracing in a direction
perpendicular to their planes
Structural steel or reinforced
concrete column support
Mechanical services