This document discusses the design of staircases. It defines the key components of staircases like treads, risers, stringers and landings. It describes different types of staircases such as straight, dog-legged and circular. It covers structural behavior factors like effective span and load distribution. Design considerations like tread and riser sizes, pitch, headroom and landing widths are presented. The steps of structural design like load calculations, bending moment analysis and reinforcement design are outlined.

2. CONTENTS
 Introduction
 Components of staircases
 Types of staircases
 Structural behaviour of staircases
 Points of consideration
 Design steps
 Numerical problem
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DESIGN OF STAIRCASE

3. 3
DESIGN OF STAIRCASE
INTRODUCTION
 Stairs consist of steps arranged in a series for
the purpose of giving access to different
floors of building.
 Since stair is often the only means of
communication between the various floors of
building, the location requires good and
careful consideration.

4. COMPONENTS OF STAIRCASE
 TREAD : The upper horizontal portion of step over which
foot is placed during ascending and descending a stairway.
 RISER : The vertical member of step. It is used to support
and connect successive treads.
 HEADROOM : The vertical height between the tread of one
flight and ceiling of overhead construction. It should be
sufficient so as not to cause any difficulty to person using
stairs
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DESIGN OF STAIRCASE

5. Contd...
 STRINGERS : These are sloping members of the stair,
used to support the end of steps.
 WINDERS : These are the steps used for changing the
direction of stairs. These are usually triangular in plan.
 FLIGHT : This consist of series of steps provided between
landings.
 RUN OR GOING : Total length of stairs in horizontal plain
including length of landings
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DESIGN OF STAIRCASE

6. Contd...
 LANDING : Horizontal platform provided at the head of
series of steps. It facilitates change of direction of flight.
 HAND RAILS : Inclined rail provided at convenient
height over steps. It serves as guard rail and provide
assistance to user steps.
 BALUSTER : Its individual vertical member fixed
between string and hand rail.
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DESIGN OF STAIRCASE

7. Contd...
 NOSING : Projecting part of tread beyond the face of
riser.
 LINE OF NOSING : The straight line joining the nosing
of various steps and parallel to slope of line.
 PITCH OR SLOPE : Vertical angle made by line of
nosing with horizontal
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DESIGN OF STAIRCASE

8. TYPES OF STAIRCASE
 STRAIGHT STAIRS
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DESIGN OF STAIRCASE
 DOG-LEGGED STAIRS  CIRCULAR STAIRS

9. Contd…
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 OPEN WELL STAIRS  CANTILEVER STAIRS  TREAD-RISER STAIRS

10. STRUCTURAL BEHAVIOUR OF STAIRCASE
 EFFECTIVE SPAN OF STAIRS
a) Where supported at top and bottom risers by beams
spanning parallel with the risers, the distance c/c of
beams.
b) Where spanning on to the edge of a landing slab,
which spans parallel, with the risers, a distance
equal to the going of stairs plus at each end either
half the width of the landing or one metre,
whichever is less.
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( IS 456:2000 – Cl. 33.1)
Fig a)

11. Contd…
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c) Where the landing slab spans in the same direction as the stairs,
they shall be considered as acting together to form a single slab and
the span determined as distance c/c of supporting beams or walls,
the going being measured horizontally.
Fig b)

12. Contd…
 DISTRIBUTION OF LOADING STAIRS ( IS 456:2000 – Cl. 33.2)
 In case of open well stairs where span partly cross at right angle, the load on
common area may distributed as one half in each direction.
 Where flights or landings are embedded into walls for a length not less than
110mm and are designed to span in direction of flight, a 150mm strip may be
deducted from load area and effective breadth of the section increased by
75mm for purposes of design.
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13. DESIGN OF STAIRCASE
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Fig c) Fig d)

14. POINTS OF CONSIDERATION
 LANDING WIDTH : Should not be less than the width of stairs.
 WIDTH OF STAIRS : Residential – 0.8m to 1m
Public – 1.8m to 2m
 TREAD : Residential – 220mm to 250mm
Public – 250mm to 300mm
 RISER : Residential – 150mm to 180mm
Public – 120mm to 150mm
 PITCH : Should be not more than 38
 HEAD ROOM
CLEARENCE
 LENGTH OF FLIGHT: Number of steps should be min. 3 and max. 12
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Not less than
200mm in any case
Not less than
200mm in any case
Should not be less than 2.1m

15. Contd…
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 STRUCTURAL DESIGN
 Effective Span calculation :
Leff = c/c distance between supports
If not given width of support can be taken in between 200 and 300mm
 Thickness of waist slab : ( IS 456:2000 Cl: 23.2.1)
By calculating span to depth ratio and after that ratio of span is
multiplying by modification factor. (fig 4, page :38)
OR, Thickness of waist slab can be assumed as (L/20) for simply
supported slab and (L/25) for continous slab.
( minimum thickness of 80mm should be given )
As per
IS 456:2000

16. Contd…
 Load Calculation :
 Dead load of slab on horizontal span: where,
ws is the dead load on slab on slope = 25⨯D⨯t (take width of slab as 1m)
R – rise , T – tread
 Dead load on one step = 0.5⨯25 ⨯ R⨯T (kN/m)
 Load of steps per metre length = (dead load on one step) ⨯ t
T
 Assume suitable floor finish
 Live load if not given take 3kN/m²(residential building) and
5kN/m²(public building)
 Find total factored load (Wu )
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17. Contd…
 Bending Moment Calculation :
 Check For Depth Of Waist Slab :
 Main Reinforcement (Ast) :
 Distribution Reinforcement : 0.12 % of b⨯D
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M = 0.125 Wu L²

18. Contd…
 Design using SP 16 design charts :
 Calculate (Mu/ bd²)
 Refer SP :16 Table 2, corresponding to fck value take % of reinforcement (pt)
 Find Ast ,
Ast = pt ⨯b⨯d
100
 Detailing.
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19. THANK YOU
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