Avail Availab able le veric verical al space space betwe between en floor floor
3.00
m
3000
mm
3
Hori Horizo zont ntal al Span Span of sta stair ir case case
1.20
mtr
1200
mm
!isers
0.15
mtr
150
mm
"
#rea$s
0.25
mtr
250
mm
%
&onrete
'-
20
σcbc
7
5.00
wt( of concrete N.mm2
415
25000
m
13.33
σst
230
m
N.m3
N.mm2
)
Steel
+
Nominal cover
25
Reinforcement 'ain ottom slab
10
mm Φ bars
100
Anchor bars /ottom 0
mm Φ bars
2
Strirrups
mm Φ bars
270
f*
x
1 mm φ
,ffective cover
2
30
mm
mm c.c
2" 1)"
12
1"
1(2 2"
12 1 mm φ
1
mm c.c
3(
1" + mm φ
2)
mm c.c
2"
1(+ 1 mm φ 1+
2
mm c.c
mm
1"
1" pknan$wana*ahoo(co(in
2()"
12
mm c.c Nos( mm c.c
DESIGN OF DOG-LEGGED STAIR N!me of "or# $%#n St!ir &!'' me!()re A+!i'!,'e +eric!' (%!ce ,et"een f'oor oriont!' S%!n of (t!ir c!(e Ri(er( Tre!/( oncrete Stee' Nomin!' co+er
2.50 * 3.00 m 1.20 m 0.15 m 0.25 m - 20 7 c,c f-
415 25
5.00 12 mm 1" mm 2" mm wt( of concrete 2" N.mm2 m 13(33 2
N.mm mm
23 30
(t
Effecti+e co+er
N.mm2 mm
1 Genral arrngment:- 4i5( shows plan of stair hall( Hei5ht of 1st fli5ht( 6 3( . 2 No( of risers re7uire$ 6 1(+ . (1" No( of trea$s re7uire$ 6 12 1 Spce occupie$ b* trea$s 6 11 x (2" 8eep wi$th of lan$in5 e7ual to ∴ Space left for passa5e
6 6 6 6 6 6
1(" 12 11 2()" 1(2 1("
Hei5ht of 1st fli5ht( No( of risers re7uire$ No( of trea$s re7uire$ Spce occupie$ b* trea$s 8eep wi$th of top lan$in5
6 6 6 6
+ No( in 2n$ fli5ht( ) No( in 2n$ fli5ht( 1()" m m
6 6 6 6
1(2 1(2 + )
2 Design Constants:- 4or H9S ars
σst = σcbc = #6 61-k.3 R 61.2xc x C x k
23 ) m;c
(1" 1 (2"
&ocrete ' 6
N.mm2
wt( of concrete m x
6
13(33 13(33 x
)
1
-
(2+=
.
3
("
x
)
x
(=
) < x
m which is hei5he
2
N.mm3
m;c<σst
= =
m . x
m minimum 1(+ No( in 1st fli5ht( No( in 1st fli5ht( m m m
6 2" N.mm2
=
13(33
6
0.2
6
0.04
(2+= 6
0.13
23
3 Loading Each Flight :- #he lan$in5 slab is assume to span in the same $irection as stair> an$ is consi$ere$ as actin5 to5ether to form a sin5le slab( ?et the bearin5 of lan$in5 slab in wall be 6 1% mm #he effective span
2()" <
?et the thickness of waist slab @6 ∴Bei5ht of slab w@ on slope 6
1(2
(1% .
"( x (2 x
1
ea$ wei5ht of horizontal area w 16 w@ x ea$ wei5ht of step is w2
∴
6
1 2
x
!2<#2 # 1" 1
2
0@6 (3 m
x
1
x
6
"
x
x
sa*
2" 1"
2
< 2" 2"
6
(
m
6 6
2 "
mm N.m2
"+31
N.m2
1+)"
N.m
2
6
6
6 ))% N 6 1 N 6 2" N #otal wei5ht 6 13% N Note( #he loa$ w on the lan$in5 portion will be 13% - 1+)" 6 +31 will not come on it( Howe a uniform value of w has been a$opte$ here( #otal ea$ wei5ht per meter run Bei5ht of fiishin5 etc( ?ive loa$
pknan$wan*ahoo(co(in
Design of waist slab :- ('(
6
,ffective $epth re7uire$ ut available 6 " Reinforcement:- Ast 6
