week 4
TRANSCRIPT
Prepared by Theong MC
Frame consists of upright load bearing members such as posts in
timber, columns in concrete or stanchions in steel which are arranged at the corners of the square or rectangular base
transfer loads of heavy structure plus any imposed loads via the frame structure members to a suitable lower ground
concrete Plain: mixture of cement, fine & coarse aggregate & water
Increases its strength during curing / hardening period
Portland cement is used – 28days
Nominal max sizes of aggregates: 40, 20, 14 and 10mm; 5mm is for precast products
Grade 7 & 10 - plain unreinforced concrete
Grade 15 & 30 – RC with lightweight aggregates
Grade 25 – RC with dense aggregates
Grade 30 to 50 – pre-stressed concrete
Eg: strength of Grade 10 = 10.0 N/mm2
Reinforcement Requirements:
Capable of achieving tensile strength without any undue strain
A material can be easily bent to any required shape
Surface must be capable of developing adequate bond between the concrete & reinforcement
Reasonable cost & acceptable to overall design concept
steel in the form of bars
mild steel (R) & high yield (T)
strength: 250 N/mm2 & 460 N/mm2
nominal sizes: 6, 8, 10, 12, 16, 20, 25, 32mm
Equipment
Bar bending machine
Equipment – cut manually
Fabric reinforcement Structural members that require only small area of
reinforcement can be reinforced by steel fabric, which can be supplied by sheets / rolls
Factory-made by welding
Sheets: 4800mm x 2400mm
Rolls: 48.00m & 72.00m with a common width of 2.40m
Total cross sectional area of main bars in mm2
Formwork A mould / box into which wet concrete can be poured
so that it will flow & finally set to the inner profile of the box
Requirements:
Strong enough to support the load of wet concrete
Must be accurately set out
Have grout-tight joints – grout leakage can cause honeycombing of the surface
Designed to be the max size that can be easily handled by hand & mechanical lifting device
Can be easily fixed using ?
Moisture content btw 15 – 20%
Formwork
Steps to build a RC framed building Setting out
RC piling (if applicable)
Pile cap / footing
Stump / ground beam
GF slab
Ground column
1st floor slab & beam
1st floor column
Roof beam
RC staircase
Timber roof trusses
Brickwork
Plumbing & sanitary
Roof tiles & flashing
Ceiling
Wall finishes
Floor finishes
Staircase finishes
Door leaves & windows
Ironmongeries
Electrical fittings
External & infrastructure work
Concrete framed
building
stumps
Ground beams
Ground floor slab
Ground floor
columns
1st floor beam &
slabs
1st floor column
Roof beam
STUMP A short column constructed on top of the pad
foundation / pile cap to support ground beam & column above
to transfer the load of a building onto the pad foundation / pile cap
to raise ground beam & ground floor slab to the required height above GL
Basic elements:
Reinforcement
Formwork
concrete
Beams supporting walls, joists, etc., at or near ground level,
itself either resting directly upon the ground or supported at both ends by piers.
used in situations where foundation walls may not be achievable
Vary in their complexity of design & reinforcement depends on loading
erected over columns or piers taken into the soil
Transfer their loadings to columns
When erecting them, the piers must be already cast in the ground
Beams Clearing the ground
Blinding layer
reinforcements are then tied and bent separately; carried and laid over the columns and blinding
Formwork erected to sides
concrete is prepared and poured
Columns Constructed from either plain concrete (1:3:6) /
reinforced concrete (1:2:4)
vertical structural element that transmits, through compression, the weight of the structure above to other structural elements below
to support beams or arches on which the upper parts of walls or ceilings rest
Columns must be properly located, and the choice of a steel beam or wood beams
Process
Superstructure
Tie up all rings around and into vertical steel bars according to design.
Fix form work of required size with vertical steel bars.
Lay cement concrete
Foundation
Excavation Steel bar, formwork, concrete to
footing
Link tied to main bar Adding spacer block
lapping Wood bracing
Sometimes, we use steel formwork
Group Activity: Compare the advantages of timber & steel formwork