1. Stairs
:- Chaudhari Tanmay. M
:-Gamit Vinay..

2. DETAILING OF STEEL IN STAIR CASES
Learning Outcomes:
After this students will be able to do the detailing of staircases through drawing and bar bending schedule.

3. Detailing of steel in Stair cases
Contents
Definition and parts of Stair cases
Types of stair cases
Requirements
Detailing principles
Problems
Art of Drawing
Bar bending schedule

4. STAIR CASE
Definition
Stair cases are used for the purpose of giving access to different floors of a structure.

5. Parts of stair a case L1 L2 FLIGHT FIG.1 PARTS OF STAIR CASELe L1 L2
FLIGHT G T N R W θ
FIG.1 PARTS OF STAIR CASE
Fig. 2 DOG LEGGED STAIR CASE

6. Parts of stairs G T N R W θ Flight and landing. Steps Rise-R
Going-G=T-N
Tread-T
Nosing -N

7. Types of stair cases Based on shape Straight stairs Dog legged stairs
Open well or open newel stairs
Geometrical stairs such as spiral, circular, etc.
Free standing stair cases

8. Transversely spanning SC
Some photos
Dog legged SC
Straight SC
Transversely spanning SC
Geometric SC

9. Open Well or Newel stair cases
II- FLIGHT
LANDING
OPEN WELL
OPEN WELL
I- FLIGHT
III- FLIGHT
WITH INTERMEDIATE FLIGHT
WITHOUT INTERMEDIATE FLIGHT

10. OTHER STAIRCASES RISER AND TREAD STAIRCASE
SPIRAL AND GEOMETRIC STAIRCASES
RISER AND TREAD STAIRCASE

11. CLASSIFICATION Based on type of span
Horizontally spanning or transversely spanning SC
Longitudinally spanning SC.
For details refer IS: and SP-34.

12. Guide lines for fixing the dimensions
Rise (R) : 150mm to 180mm
Tread (T) : 220 mm to 250 mm- for residential buildings.
Rise (R) : 120 to 150 mm
Tread (T) : 250 mm to 300 mm – for public buildings
[T + 2R] : Between 500 mm to 650 mm
The width of the stair
0.8 m to 1 m for residential building and
1.8 m to 2 m for public building.

13. Guide lines for fixing the dimensions Contd…
The width of the landing is equal to the width of stairs.
The number of steps in each flight should not be greater than 12
The pitch of the stair should not be more than 38 degrees.
The head room measured vertically above any step or below the mid landing shall not be less than 2.1 m.

14. Design of stairs
Design for maximum bending moment and check for maximum shear force.
The depth is to be fixed from deflection criteria.
Stair case slab is designed as a conventional slab.
All rules regarding the detailing are similar to that of slab.
Enough development and anchorage lengths for steel should be provided.

15. Transversally spanning stair case
0.5 Ast
0.1Le-0.15Le Le
Ast
MAIN STEEL
STEPS
STRINGER BEAMS
STRINGER BEAM D1 D2
STIRRUP
DIST. STEEL
Refer SP-34 for more details

16. STAIR CASE SUPPORTED ON SIDE BEAMS-DETAILS
TRANSVERSLY SPANNING
MAIN Ast
0.5Ast DS DB bW L
6φm Le Le φm
STAIR CASE SUPPORTED ON SIDE BEAMS-DETAILS
STIRRUP DETAILS AND HOOK

17. EFFECTIVE SPAN FOR LONGITUDINALLY SPANNING STAIRCASESLe
LANDING
WAIST SLAB
WALL
EFFECTIVE SPAN FOR LONGITUDINALLY SPANNING STAIRCASES
WAIST SLAB SUPPORTED AT THE ENDS OF LANDINGS
Case (a)

18. EFFECTIVE SPAN FOR LONGITUDINALLY SPANNING STAIRCASES GOING=G LeX Y
EFFECTIVE SPAN FOR
LONGITUDINALLY
SPANNING STAIRCASES Le
Case (b)
Le=G +[ X +Y], X ≤1m AND Y ≤1m Le
Case (c)
Le=c/c of beams

19. Longitudinally spanning SC
Detailing
Steel at bottom longitudinally-tension
Anchorage and development steel
Distribution steel
Row of chairs
Nominal foundation for ground flight

20. Exercise A dog legged stair case is to be detailed with the
following particulars:
Clear dimension of stair case room=4.48 m x 2.1 m
The floor to floor height is 3.2 m
Width of each tread =250 mm
Width of each rise = 160 mm
Thickness of waist slab = 150 mm
Width of flight =1m
All round wall = 230 mm

21. Exercise contd., Both flights are supported at the ends of
landing on 230 mm wall.
(Landing and flight spans in the same direction)
The first flight starts from the plinth level
Main steel for each flight =
Distribution steel for each flight = 200
Use M20 concrete and Fe 415 steel.
Draw to a suitable scale
The plan of stair case
Sectional elevation of the Ground flight
Sectional elevation of the First flight
Bar bending schedule

22. Solution Dimensioning: R=160 mm, T= 250 mm
Floor to floor height = 3200mm
No of rises = 3200/R = 20. Each flight has 10 rises.
No of treads per flight=10-1 =9
Width of landing along flight
= (4480-9x250)/2 = 1115mm.
Going of flight=9x250 =2250mm
Development length = 47φ= 47 x 12 = 564 mm

23. Exercise Plan of stair case PLAN 2100
1115 mm
2250 mm
Le = 4710 mm
Gap=0.1m
2100
Clear dimension of stair case room=4.48 m x 2.1 m

24. DETAILING [A] [C] [D,E]- Anchorage steel
ROW OF CHAIRS
500 mm GL
Wall
FOUNDATION
GROUND FLIGHT
MAIN STEEL
# 120
DIST. STEEL
# 200
150
Ld =564
REINFORCEMENT
FROM BM
FLOOR LEVEL
LANDING
FIRST FLIGHT
R=160
T= 250
LAP L
Main steel [B]
[A]
[C]
[D,E]- Anchorage steel
Landing and flight spans longitudinally

25. DETAILING Flight spans longitudinally on landing beams Y=0.3 l or Ld
500 GL
FOOTING
GROUND FLIGHT
FIRST FLIGHT
MAIN STEEL # 120
DIST. STEEL
# 150
150 X l Y
INTERMEDIATE
LANDING
ROW OF CHAIRS
X = 0.15 l or Ld
MAIN STEEL DS Le
PLAN
Flight spans longitudinally on landing beams

26. Details at the junction of flight and landingLd T
Extra steel if needed
Concrete spalling due to tension in steel
Wrong ok

27. STRAIGHT STAIR CASE
Refer SP-34 and learn the details

28. Bar bending schedule For exercise problem Mark No. of bars Dia. in mm
Member
Mark
No. of bars
Dia.
in mm
Length
in m/piece
Total length in m
Bar details
Remarks
#12 #8 SC
GFl A 9 12
measure X1 8
spacings, main bar B X2
Main bar C
Count
960 Y1
Dist. Bar
L=1000-2EC

30. Estimation of quantity of concrete
Volume of concrete = L x B x D
L= length along the central line in m-measured
B=Breadth in m
D=Thickness of slab in m
Plus concrete in footing
Weight of concrete, kg = Volume x density

31. Conclusion Students have learnt the following: Types of staircases.
Effective span concept.
Requirements of staircase.
Detailing of steel.
Importance of development length and anchorages.
Drawing to scale and bar bending schedule.

32. The end
Thank you very much
Dr. M. C. Nataraja