Design of Metal Deck Sheet and Composite I-Section as secondary member
How do you takeoff a staircase?
1. Summary Sheet
Session Number :
Date :
Subject Expert :
1
12.03.2007
Dr. M.C. NatarajaDr. M.C. Nataraja
Professor
Department of Civil Engineering,
Sri Jayachamarajendra College of Engineering,
Mysore – 570 006.
Phone:0821-2343521, 9880447742
E-mail: nataraja96@yahoo.com
2. Learning Outcomes:
• After this students will be able to do the detailing ofAfter this students will be able to do the detailing of
staircases through drawing and bar bendingstaircases through drawing and bar bending
schedule.schedule.
DETAILING OF STEEL IN
STAIR CASES
3. Contents
• Definition and parts of Stair cases
• Types of stair cases
• Requirements
• Detailing principles
• Problems
• Art of Drawing
• Bar bending schedule
Detailing of steel in Stair
cases
5. Parts of stair a caseParts of stair a case
G
T
N
R
W
θ
Le
L1
L2
FLIGHT
FIG.1 PARTS OF STAIR CASE
Fig. 2 DOG LEGGED STAIR CASE
6. Parts of stairsParts of stairs
Flight and landing.
Steps
Rise-R
Going-G=T-N
Tread-T
Nosing -N
G
T
N
R
W
θ
7. Types of stair casesTypes 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
9. Open Well or Newel stair casesOpen Well or Newel stair cases
I- FLIGHT
II- FLIGHT
III- FLIGHT
LANDING
WITH INTERMEDIATE FLIGHT WITHOUT INTERMEDIATE FLIGHT
OPEN
WELL OPEN
WELL
11. Based on type of spanBased on type of span
• Horizontally spanning or transversely
spanning SC
• Longitudinally spanning SC.
For details refer IS:456-2000 and SP-34.
CLASSIFICATION
12. Guide lines for fixing the dimensionsGuide 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 dimensionsGuide lines for fixing the dimensions Contd…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 stairsDesign 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 caseTransversally spanning stair case
STEPS
STRINGER
BEAMS STRINGER
BEAM
0.5 Ast
0.1Le-0.15Le
Le
Ast
D1
D2
STIRRUP
MAIN STEEL
DIST. STEEL
Refer SP-34 for more details
19. Longitudinally spanning SCLongitudinally spanning SC
DetailingDetailing
• Steel at bottom longitudinally-tension
• Anchorage and development steel
• Distribution steel
• Row of chairs
• Nominal foundation for ground flight
20. ExerciseExercise
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. ExerciseExercise contd.,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 = #12@120
Distribution steel for each flight = #8@ 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. SolutionSolution
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. ExerciseExercise
Plan of stair case
PLAN
1115 mm 1115 mm2250 mm
Le = 4710 mm
Gap=0.1m 2100
Clear dimension of stair case room=4.48 m x 2.1 m
24. ROW OF CHAIRS
500 mm
500 mm
GL
Wall
FOUNDATION
GROUND FLIGHT
MAIN STEEL
# 12 @ 120
DIST. STEEL
# 8 @ 200
150
Ld =564
REINFORCEMENT
FROM BM
Ld =564
FLOOR LEVEL
LANDING FIRST FLIGHT
R=160
T= 250
LAP L
DETAILING
Landing and flight spans longitudinally
[A]
[C]
[D,E]-
Anchorage
steel
Main steel [B]
25. Y=0.3 l or Ld
LANDING
BEAM
500
500
GL
FOOTING
GROUND FLIGHT
FIRST FLIGHT
MAIN STEEL # 12 @ 120
DIST. STEEL
# 8 @ 150
LANDING
BEAM
150
X
l
Y
Y
150
INTERMEDIATE
LANDING
ROW OF
CHAIRS
X = 0.15 l or Ld
MAIN STEEL
DS
150
PLANLe
DETAILING
Flight spans longitudinally on landing beams
26. Ld
Ld
T
Extra steel if
needed
Concrete spalling
due to tension in
steel
Wrong
ok
Details at the junction of flight and landingDetails at the junction of flight and landing
29. Stair-
Ground
Floor
D 9 12 measure X3
Anchorage
bars
E 9 12 measure X4
Anchorage
bars
Total length in m/diameter - -
Calculations are based on
actual measurement on
drawing sheet.
Weight in kg/m -- --
Total weight in kg/diameter --- ---
Bar bending schedule-
Contd.,
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.
