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Design of Staircase: 1.load Calculation

The document provides calculations for the design of a staircase. It includes calculations for the load on each component, including the steps, landings, and cantilever slab. It determines the factored load, effective depth, tension steel reinforcement, shear capacity, development length, and deflection for the stair slab design. Reinforcement is checked to satisfy requirements for strength, shear, development length, and deflection.

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1K views6 pages

Design of Staircase: 1.load Calculation

The document provides calculations for the design of a staircase. It includes calculations for the load on each component, including the steps, landings, and cantilever slab. It determines the factored load, effective depth, tension steel reinforcement, shear capacity, development length, and deflection for the stair slab design. Reinforcement is checked to satisfy requirements for strength, shear, development length, and deflection.

Uploaded by

Its me
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as XLSX, PDF, TXT or read online on Scribd
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DESIGN OF STAIRCASE

CALCULATION
1.load calculation

Standard Value

Tread(T)= 0.233 m
Riser = 0.15 m
no. of Risers= 12
no. of Tread= 11
no.of Landings= 2
Floor height= 3.505 m
Depth of waist slab= 250 mm
0.25 m
Width of flight= 1.8 m
Width of landing 1= 1.4 m
Width of landing 2= 1.4 m
Density of concrete= 25 KN/m
Density of steel= 415 KN/m
Floor finish= 0.05 m
STRUCTURAL DESIGN
A) Dead load on steps
Steps section= 0.017475 m
0.436875 `KN/m
Inclined slab= 0.069277 m
1.731927 KN/m
Finish= 0.01915
0.47875 KN/m
Total dead load= 2.647552 KN/m
Dead load of flight per m on plan area= 11.36288 KN/m
LL/m on plan= 5 KN/m
Total load= 11.36288
Factored load= 24.54432
Taking 1.8 m width of slab 1.8 m
load= 44.17978 KN/m 0

B) Load on landing A
Self weight of slab= 6.25 KN/m
Floor finish= 1.25 KN/m
LL= 5 KN/m
Total dead load= 7.5 KN/m
Factored load= 18.75 KN/m
Design load= 26.25 KN/m
In a distance of 150mm from wall there will be no live load.
In a distance of 150mm from wall and at a distance of 75mm inside wall only dead load is considered.

Design load= 15.75

C) Load on landing B
Self weight of slab= 6.25 KN/m
Floor finish= 1.25 KN/m
LL= 5 KN/m
Total dead load= 7.5 KN/m
Factored load= 18.75 KN/m
Design load= 26.25 KN/m

In a distance of 150mm from wall there will be no live load.


In a distance of 150mm from wall and at a distance of 75mm inside wall only dead load is considered.

Design load= 15.75 KN/m

d) Load of cantilever slab


weight of slab on beam= 4.00125 KN/m
floor finish= 1.333 KN/m
Total load= 5.33425 KN/m
LL= 3.201 KN/m
Factored DD= 8.00138
Factored LL= 4.8015
Factored total load= 12.8029

now stair slab can be analysed as beam with one end fixed and another end hinged
from sap
Reaction at A (RA)= 162.929 KN
Reaction at b (RB)= 91.781 KN
shear force is maximum at x=2.19071 m from support A
therefore ,maximum bending moment (Bmmax)= 124.0329 KNm

Effective depth of slab


BM=0.138fckbd
d= 141.3262
Adopt effective depth= 224 mm
Overall depth= 250 mm
Area of tension steel is given as:
BM=0.87fy*Ast*(d-fy*Ast/(fck*b))
Ast= 1645.045 mm

Use 9 16 mm bars
Use 9-16 mm bar equally spaced in 1.8mm width
At,p= 1808.64 mm2
Diameter= 16 mm
Check for shear:

normal shear stress(Tv)= Vu/(bd)


0.40409 N/mm2
pt=100Ast/bd= 0.448571 %

Shear strength of M25 concrete for 0.448571% of steel

Tc= 0.4632 N/mm2


k= 1.1
shear strength for slab=Tc'=kTc= 0.50952 > 0.40409 N/mm2
o.k
check for development length:

Development length for 16 mm bar, Ld=47= 752 mm

MR of 9-16mm bars, M1= 136.3676 KN-m


V= 162.929 KN
L0=12 or d ,whichever is greater = 224 mm

Ld 1.3*M1/V+L0 1086.574 mm

or, 47 1086.574mm
23.1185 mm

ok

check for deflection (IS 456:2000 clause 23.2.1)

% of steel =100 Ast/(bd) = 0.448571 %


Ast,req = 1645.045
Ast,p = 1808.64

fs=0.58*fy*Ast,req/Ast,p = 218.9282
l/d = 16.78125
a = 23
b = 1
c ( from graph ) = 1.38
d = 1
e = 1
abcde = 31.74 > l/d
ok
hence ,the slab is safe in deflection.
KN/m
only dead load is considered.

only dead load is considered.

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