no slide title · quarter turn dog leg spiral timber concrete steel brick . configuration of...
TRANSCRIPT
STAIRS
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Why do we need to learn about
Stairs
• Functional requirements
• Design considerations
• Types of Stairs
• Accessibility
• Circulation / Flow
• Fire escape
• Interconnectivity of
space
OBJECTIVES 1. State the functional requirements of stairs
2. Define the various terminology related to stairs
3. Identify the different forms of staircase construction and list the design considerations of staircases.
4. Describe the characteristics of different staircases and compare their advantages and disadvantages.
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Introduction
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Staircases provide a mean of access between different floor levels within a building
Functions of Stairs
• To allow normal access from floor to floor
• To allow escape from upper floors in the event of
fire
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1. Strength & stability
2. Fire Resistance
3. Sound Insulation
4. Aesthetics
Functional Requirement
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Shape
CLASSIFICATION
Materials
Straight
flight
Quarter
turn
Dog leg
Spiral
Timber
Concrete
Steel
Brick
Configuration of Staircases
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Configuration of Staircases
Straight Flight Stairs
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Quarter Turn Stairs
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Half Turn (dog-leg) Staircases
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Spiral Stairs
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Shape
CLASSIFICATION
Materials
Straight
flight
Quarter
turn
Dog leg
Spiral
Timber
Concrete
Steel
Brick
Timber Stairs
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Concrete Stairs
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Brick Stairs
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Metal Stairs
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Composite Stairs
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• combination of at least
two different materials
• made of concrete or steel
• composite stairs are steel
support with concrete or
timber treads
Components of A Staircase • Treads and Risers
• Strings
–Closed String
–Open or Cut String
• Landings
• Balustrades
–Open balustrade
–Closed balustrade
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Open Strings
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Cut to the profile of the treads and
risers to support them
Closed Strings
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Encloses the treads and risers which it
supports and top edge protrude 50-
63mm above nosing
Landings
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Handrail,Baluster & Newel Post
Newel post
Handrail
Baluster
Closed Balustrades
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Consists of framed or
unframed panels acting as
baluster to support the handrail
Open Balustrades
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Vertical balusters spaced at
certain interval to support the
handrail
Handrails &
Balustrades
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Stair Terminology Stair Terminology
Stair Terminology Stair Terminology
Basic Design Considerations
• The risers and treads within each flight of stairs shall be of uniform height and size.
• The height of a riser shall not be more than 175 mm. The width of a tread shall not be less than 275 mm. The width of a tread of any staircase in any residential unit shall not be less than 225mm. The width of a tread of any staircase in any industrial building shall not be less than 250mm. The width of the tread of any tapered step shall be taken as that when measured at a distance of 500mm from the narrower end.
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Tread
Riser
• The pitch of the stair shall be a maximum of 42°.
The clearance of headroom should not be less
than 2.0 m measured vertically above pitch line.
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Basic Design Considerations
• A landing shall be provided at every floor
level and door opening.
• Except for spiral staircases, an intermediate landing shall be provided in between floor levels at intervals of not more than 18 risers.
• The clear width of any landing, measured from the handrail or kerb (whichever protrudes further into the landing) to the wall or external railing of the landing, shall not be less than 900 mm
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Basic Design Considerations
Width of Stair & Landing (min 900mm)
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• A handrail shall be provided on at least one side of
the flight of staircase
• The height of the handrail shall be between 750mm
and 1000mm above the pitch line.
• Where there is a vertical drop in level of 1.0 m or
more (for a staircase with more than say 5 steps),
appropriate measures shall be taken to prevent
people from falling from a height. Where a barrier is
used to prevent falling from a height, the barrier shall
not have any feature that facilitates the climbing of
the barrier. The height of a barrier shall not be less
than 1.0 m. The height of a barrier at the flight of
stairs is measured vertically from the pitch line to the
top of the barrier.
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Basic Design Considerations
Handrails shall:
• have a circular section of
32mm to 50mm in diameter or
an equivalent gripping surface;
and
• have a clear space between
the handrail and all wall
surface –
– (i) not less than 40mm; or
– (ii) at least 60mm where
the wall has a rough
surface.
• A recess containing a handrail
shall extend at least 450mm
above the top of the rail
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Basic Design Considerations
For a flight of staircase,
a) In all buildings, except for industrial buildings, any
triangular opening or void formed around a tread,
riser and the bottom edge of the barrier, the size of
any opening or gap shall not be large enough as to
permit the passage of a sphere of a diameter of
150mm.
b) In all buildings, except for industrial buildings, the
gap size between any two consecutive steps shall
not be large enough as to permit the passage of a
sphere of a diameter of 100mm; and
c) In industrial buildings, the gap size between any
two consecutive steps shall not be large enough as
to permit the passage of a sphere of a diameter of
150mm.
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Basic Design Considerations
• Number of risers is not to exceed 18 in any flight of steps. Except for spiral, circular or geometric staircases, an intermediate landing shall be provided in between floor levels at intervals of not more than 18 risers.
• The width of landings should not be less than the width of the stairway.
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Basic Design Considerations
Concrete Staircases • Most common
• Advantages
– good fire resistance
– Strong
– better sound insulation
• Disadvantages
– Slow in erection – wet
process
– Proper training
required
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Requirements: – Concrete Grade 30 or above
– Minimum concrete cover 20 mm
– Waist thickness between 100 to 250mm
– Mild steel or high yield steel bars can be used as reinforcement
– Handrail to be at least 900 mm above the pitch line
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Concrete Staircases
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Concrete cover
Waist thickness
Min 900 mm
Hand-
railing
Concrete Staircases
Finishes – Warehouse – natural finishes. Add carborundum dust
/ rubber strips for slip resistance
– PVC tiles
– Rubber tiles
– Carpet mats
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Concrete Staircases
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Concrete Staircases
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Precast Staircases Advantages • Better quality
control
• Saving in site space
• Faster construction
• Installation is simple.
Disadvantages
• Requires mass production.
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Precast Concrete Treads
Precast Staircases
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Precast Staircases
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Precast Staircases
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