04. Design of Staircase_04

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Name of work :-

1 Stair Room Size x m

2 Available verical space between floor m mm

3 Horizontal Span of Staircase mtr mm

4 Risers mtr mm

5 Treads mtr mm

6 Conrete M - N/m3

scbc N/mm2 m

7 Steel fy sst N/mm2

8 Nominal cover mm

Reinforcement

Main Bottom slab mmF bars mm c/c

Anchor bars (Bottom ) mmF bars Nos.

Strirrups mmF bars mm c/c

12 mmf 300 mm c/c

150 1.20

250

12 mmf 150 mm c/c

3.00 150

8 mmf 280 mm c/c 250

1.80

12 mmf 300 mm c/c

170 mm

2.75

DESIGN OF DOG-LEGGED STAIR

10

150

2

280

20

415

12

12

Effective cover

2.00

30

230

13.33

1.25

0.15

wt. of concrete 25000

500 1250

1750 1250

150

250

1250

500

1500

Staircase Design

30003.00

4.50

1250

7

20

0.25


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Name of work :-

Stair Room Size 2.00 x 4.50

Available verical space between floor 3.00 m

Horizontal Span of Staircase 1.25 m 1250 mm

Risers 0.15 m 150 mm

Treads 0.25 m 250 mm

Concrete M- 20 N/mm2

cbc 7 mSteel fy- 415 N/mm st N/mmNominal cover 20 mm mm

1 Genral arrngment:-

Fig. shows plan of stair hall.

= 3.00 / 2 = 1.50 m minimum 1.8 m which is heigher

No. of risers required = 1.80 / 0.15 = 12 No. in 1stflight.

No. of treads required = 12 - 1 = 11 No. in 1st flight.

Spce occupied by treads = 11 x 0.25 = 2.75 m

Keep width of landing equal to = 1.25 m

\ Space left for passage = 0.50 m= 1.20 m

No. of risers required = 1.20 / 0.15 = 8 No. in 2nd

flight.

No. of treads required = 8 - 1 = 7 No. in 2nd flight.

Spce occupied by treads = 7 x 0.25 = 1.75 m

Keep width of top landing = m

2 Design Constants:-For HYSD Bars = 20

sst = 230 N/mm2 = 25000 N/mm2

scbc = 7 N/mm3 m = 13.33x

13.33 x 7 + 230

j =1-k/3 = 1 - 0.289 / 3 =R =1/2xc x j x k = 0.5 x 7 x 0.904 x 0.289 =

3 Loading Each Fl ight :-

The landing slab is assume to span in the same direction as stair, and is considered

= 160 mm

The effective span= 2.75 + 1.25 +( 0.16 / 2 )'= 4.08 m say = m

Let the thickness of waist slab '= 4.50 x 40 = mm

\Weight of slab w' on slope = 0.18 x 1 x 1 x = N/m2

R2+T

2 150 2+ 250

T

1 150

2 1000

\ Total Dead weight per meter run = N= N

= N

Total weight = N

Note. The load w on the landing portion will be 9723 - 1875 = will not come on it. However,

a uniform value of w has been adopted here.

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25000

13.33

230

30

Height of 1st

flight.

0.904

0.289

Height of 1st

flight.

Effective cover

wt. of concrete

9723

7123100

2500


=

Cocrete M

0.913

m*c+sst

wt. of concrete

xx

25000

250

####

4.00

180

4500

N/m

2=

5248

=

=13.33

1875

Weight of fiishing etc.

Dead weight of step is w2 =

Dead weight of horizontal area w1= w' x =

Staircase Design

7848

4500 x

as acting together to form a single slab. Let the bearing of landing slab in wall be

7k =

m*c

N/m2

Live load
mailto:[email protected]:[email protected]


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4 Design of waist slab :-

wl2 9723 x 4.00 2

B.M. = 8

Rxb 0.913 x 1000

But available = 146 + 2x cover = 20 = 166 mm say = 170 mm

5 Reinforcement:-

230 x 0.904 x 1463.14xdia

23.14 x 12 x 12

4 x100 4 x

641 x 1.25

= 1250 / 8 = 156 mm c/c

Hence used 12 = 150 mm c/c

Distribution steel = 0.12 x 146 x 1000

3.14xdia2

3.14 x 8 x 8

4 x100 4 x

50 x 1000

Hence used 8 = 280 mm c/c

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Spacing

640.97 mm2BM x 100

sst x j x D=

19446000

=

Ast =

No

mm F bars

8

using 8 mmF bars A

100= 175

=

=Nomber of Bars

using 12 AmmF bars

113.04=

= 113 mm2100

= 19446 N-m

146 mm=

175.13

mm F bars

Spacing =

19446000=Effective depth required =

mm c/c287

=

mm2

=

=8

mm2

=

= = 50100


4/8

UP4.50

11

10

9 8 mm F 280

8

7

#REF! mm F #REF! 6

5

4

3

2

1

Foor level

1.25

150

0.502.75


1.25

2.00

1.25

2.75

0.50

250


5/8

150 1.20

250

12 mmf 150 mm c/c

3.00 0

8 mmf 280 mm c/c 0

170 mm

1.80

2.75

[email protected]

500

500 1250

1500

1750 1250

1250


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M-15 M-20 M-25 M-30 M-35 M-40

18.67 13.33 10.98 9.33 8.11 7.18

5 7 8.5 10 11.5 13

93.33 93.33 93.33 93.33 93.33 93.33

kc 0.4 0.4 0.4 0.4 0.4 0.4

jc 0.867 0.867 0.867 0.867 0.867 0.867

Rc 0.867 1.214 1.474 1.734 1.994 2.254

Pc (%) 0.714 1 1.214 1.429 1.643 1.857

kc 0.329 0.329 0.329 0.329 0.329 0.329

jc 0.89 0.89 0.89 0.89 0.89 0.89

Rc 0.732 1.025 1.244 1.464 1.684 1.903

Pc (%) 0.433 0.606 0.736 0.866 0.997 1.127

kc 0.289 0.289 0.289 0.289 0.289 0.289

jc 0.904 0.904 0.904 0.904 0.904 0.904

Rc 0.653 0.914 1.11 1.306 1.502 1.698

Pc(%) 0.314 0.44 0.534 0.628 0.722 0.816

kc 0.253 0.253 0.253 0.253 0.253 0.253

jc 0.916 0.916 0.916 0.914 0.916 0.916

Rc 0.579 0.811 0.985 1.159 1.332 1.506

Pc (%) 0.23 0.322 0.391 0.46 0.53 0.599

M-15 M-20 M-25 M-30 M-35 M-40

0.18 0.18 0.19 0.2 0.2 0.2

0.22 0.22 0.23 0.23 0.23 0.23

0.29 0.30 0.31 0.31 0.31 0.32

0.34 0.35 0.36 0.37 0.37 0.380.37 0.39 0.40 0.41 0.42 0.42

0.40 0.42 0.44 0.45 0.45 0.46

0.42 0.45 0.46 0.48 0.49 0.49

0.44 0.47 0.49 0.50 0.52 0.52

0.44 0.49 0.51 0.53 0.54 0.55

0.44 0.51 0.53 0.55 0.56 0.57

0.44 0.51 0.55 0.57 0.58 0.60

0.44 0.51 0.56 0.58 0.60 0.62

0.44 0.51 0.57 0.6 0.62 0.63

M-15 M-20 M-25 M-30 M-35 M-401.6 1.8 1.9 2.2 2.3 2.5

VALUES OF DESIGN CONSTANTS

Grade of concrete

Modular Ratio

scbc N/mm2

m scbc

(a) sst=140

N/mm2

(Fe 250)

(b) sst=190

N/mm2

(d) sst=275

N/mm2

(Fe 500)

Permissible shear stress Table vin concrete (IS : 456-2000)

100As Permissible shear stress in concrete tv N/mm2

(c ) sst=230

N/mm2

(Fe 415)

2.50

bd

< 0.15

0.25

0.50

0.751.00

tc.max

2.753.00 and above

Maximum shear stress tc.max in concrete (IS : 456-2000)

Grade of concrete

1.25

1.50

1.75

2.00

2.25


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rade of concret M-10 M-15 M-20 M-25 M-30 M-35 M-40 M-45

tbd (N / mm2) -- 0.6 0.8 0.9 1 1.1 1.2 1.3

M 15

M 20

M 25

M 30

M 35

M 40

M 45

M 50

(N/mm2) Kg/m2 (N/mm2) Kg/m

2

M 10 3.0 300 2.5 250

M 15 5.0 500 4.0 400M 20 7.0 700 5.0 500

M 25 8.5 850 6.0 600

M 30 10.0 1000 8.0 800

M 35 11.5 1150 9.0 900

M 40 13.0 1300 10.0 1000

M 45 14.5 1450 11.0 1100

M 50 16.0 1600 12.0 1200 1.4 140

1.2 120

1.3 130

1.0 100

1.1 110

0.8 80

0.9 90

-- --

0.6 60

Grade of

concrete

Permission stress in compression (N/mm2) Permissible stress in bond (Average) for

plain bars in tention (N/mm2)

(N/mm2) in kg/m2

Bending acbc Direct (acc)

Permissible Bond stress Table bdin concrete (IS : 456-2000)

Development Length in tension

Grade of

concrete

Plain M.S. Bars H.Y.S.D. Bars

tbd (N / mm2) kd= LdF tbd (N / mm2) kd= LdF

0.6 58 0.96 60

0.8 44 1.28 45

0.9

1.4 25 2.24

39 1.44 40

1 35 1.6 36

33

1.2 29 1.92 30

28

1.1 32 1.76

1.3

26

Permissible stress in concrete (IS : 456-2000)

27 2.08


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04. Design of Staircase_04

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