How do you takeoff a staircase?
-
Upload
duc-tran-xuan -
Category
Documents
-
view
2.567 -
download
0
description
Transcript of How do you takeoff a staircase?
Summary SheetSession 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: [email protected]
Learning Outcomes:
• After this students will be able to do the detailing of After this students will be able to do the detailing of staircases through drawing and bar bending staircases through drawing and bar bending schedule. schedule.
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
Detailing of steel in Stair cases
STAIR CASE
Definition
Stair cases are used for the purpose of giving access to different floors of a structure.
Parts of stair a caseParts of stair a case
G
T
N
R
W
θ
Le
L1L2
FLIGHT
FIG.1 PARTS OF STAIR CASEFig. 2 DOG LEGGED STAIR CASE
Parts of stairsParts of stairs
Flight and landing.
StepsRise-RGoing-G=T-NTread-TNosing -N
G
T
NR
W
θ
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
Straight SC
Geometric SC
Dog legged SC
Transversely spanning SC
Some photos
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
OTHER STAIRCASESOTHER STAIRCASES
SPIRAL AND GEOMETRIC STAIRCASES RISER AND TREAD STAIRCASE
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
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.
Guide lines for fixing the dimensions Guide 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.
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.
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
MAIN Ast
0.5Ast
DS
DB
bW
L
6φm
Le
0.1-0.15Le
φm
DS
STAIR CASE SUPPORTED ON SIDE BEAMS-DETAILS
STIRRUP DETAILS AND HOOK
TRANSVERSLY SPANNING
Le
LANDING
WAIST SLAB
Case (a)
EFFECTIVE SPAN FOR LONGITUDINALLY
SPANNING STAIRCASES
WALL
WAIST SLAB SUPPORTED AT THE ENDS OF LANDINGS
EFFECTIVE SPAN FOR
LONGITUDINALLY
SPANNING STAIRCASES
X X Y Y
Le
Case (c)
Case (b)
Le
Le=G +[ X +Y], X ≤1m AND Y ≤1m
Le=c/c of beams
GOING=G
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
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
Exercise Exercise 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 levelMain steel for each flight = #12@120 Distribution steel for each flight = #8@ 200Use M20 concrete and Fe 415 steel.
Draw to a suitable scaleThe plan of stair caseSectional elevation of the Ground flightSectional elevation of the First flightBar bending schedule
SolutionSolution
Dimensioning: R=160 mm, T= 250 mmFloor to floor height = 3200mmNo of rises = 3200/R = 20. Each flight has 10 rises.No of treads per flight=10-1 =9Width of landing along flight
= (4480-9x250)/2 = 1115mm.Going of flight=9x250 =2250mmDevelopment length = 47φ= 47 x 12 = 564 mm
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
ROW OF CHAIRS
500 mm
500 mm
GL
Wall
FOUNDATION
GROUND FLIGHT
MAIN STEEL# 12 @ 120
DIST. STEEL# 8 @ 200
150
Ld =564
REINFORCEMENTFROM BM
Ld =564FLOOR 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]
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
INTERMEDIATELANDING
ROW OF CHAIRS
X = 0.15 l or Ld
MAIN STEEL
DS
150
PLANLe
DETAILING
Flight spans longitudinally on landing beams
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
STRAIGHT STAIR CASESTRAIGHT STAIR CASE
Refer SP-34 and learn the details
Member MarkNo. of bars
Dia.in
mm
Lengthin
m/piece
Total length in m
Bar details Remarks
#12 #8
SCGFl
A 9 12 measure X18
spacings, main bar
B 9 12 measure X2 Main bar
C Count 8 960 Y1Dist. BarL=1000-
2EC
Bar bending scheduleFor exercise problem
Stair-Ground
Floor
D 9 12 measure X3Anchorage
bars
E 9 12 measure X4Anchorage
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.,
Estimation of quantity of concrete
Volume of concrete = L x B x D
L= length along the central line in m-measuredB=Breadth in mD=Thickness of slab in m
Plus concrete in footing
Weight of concrete, kg = Volume x density
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.
The end
Thank you very much
Dr. M. C. Nataraja