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Stairs
Second edition
Alan and Sylvia Blanc
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Concrete stairs
8.1 Early forms
-1'lie earliest forms of concrete stai1-sxc '
I<oiiian where concrete was placed o\w
Ixick vaulting to support ramps or steps
such as in the construction of tlie
Colosseum (Figure8.1a).The introduction
o f
filler joist flooring in theeiglitcenthcen-tulg., with wrought-iron beams infilled ly
lit-ick arches,wasadapted t ostaircasescxi-
tile\,eredoff masonry walls (Figure8.1h).
Thee d y use of concrete in the twenti-
eth century \V;IS found in composite forms
of lxiilcling. I n the case of stairs,steel joists
often foi-med tlie stringers to reinforced
roncrete infilling (Figure 8.1c). Nenri,
OIIC of the fincst concrete engineers,
clesigiied 21 minimum doul,le-spii;il staii.
for the F I O ~ ~ I I W Sports Stadium (Figure8.1 l ) . Ilis :i\;ant-garde npprox-I1 t o rein-
forcwiientdesign is not without proljlems,
1osh of co~'ero the exposed main 1,e;iins
Ii;t\.ingled to extensive repairs.
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Concrete stairs 137
8.2 Developed forms ofreinforced concrete stairs
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138 Stairs
v -
L,' 7
L-
Thicker slabto preserve soffit
ross span for
Landing Wellbeam
L _ _ _ _ _ _ J
Key plan (showing landing beam or slab)
Cantilever stepsI
Cantileverslab
Extendedbeam
Key plan
Key section
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Concrete stairs 139
'L ' shaped tread andriser planks
P re-cast edgeframe including -strings. notchedto receive risers
Pre-cast landing-slabs
Ceramic tile fixed at work
Pre-cast stringw
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140 Stairs
Connectedto frame or
wall-bearing Cantilever end/to carry balustrade/
P re-cast tread and
Connectionto frame or to wall bearing
Twin pre-cast beams
Bracing by steelhandrailassembly
Saddle joint over'v\pine beams with
bolting in both directions
1.
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Concrete stairs 141
-Bracket
- -I 1 ..-
Height to
follow basic
plate set screwed to back
Guardina
Upstand wallfollows basicgeometry of stairs
Solid balustradeReinforced concrete upstand wall(in fair faced finish)
8.3 Pre-cast spiral stairs
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142 Stairs
qround floor
-7
. ~4
-330-rc stair
U L J , larta
SECTION A-A xa k I 10
RBmm concrete wII
with 13mmp1aterJ F Abothsides -_-
25 mmdamms bolurters
[ e m m axe / 127r279mmpocket4-I t
L i p J
ELEVATION OF TREAD C scale I 10
191mm deep pocket/
PLAN scale 153
PLAN OF TREAD C Fale I 10SECTION E-E xale I 10
41mm dam Columbpine hondrail
Rabrnrny J
.~
plaster f t
127
4
nut and washer--,
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Concrete stairs 143
F&
shc
A Y
Moulded coved//skirting tiles .+ \,; Riser tiles
and
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144 Stairs
Mortice for balustrade
Well stri
(terrazzo finish)
terrazzo strings '(reinlorcement top and bottom)
Pre~casterrazzoplanks
in-situ terrazzo
reintorcement\
\C stairspre-castOR in-situ Fa'r
lor paint
8.4Detailing
ofwell endsand balustrades
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Concrete stairs 145
1400
i
4
Lower flight
Galvanizedsteel angle frame to landing (infill of pre-cast slates)
r landing if needed
Stay atmid height
J p
P re-cast ringsand treads withteel rod
ba lytrade steel tubular/ columnL
Standardsto eachtread
30
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146 Stairs
Metal Mustracks to concrete stairs k)l-lom- the principles laid clown in C1i;ipter 7,
the differences arising if reinforced coti-
crete fender spine \v:ills :ire in \ .o l \~~l .
The achwmges of the latter rest m,itli
less metalwork to install :incl maintain.
Figure 8.Sg demonstrates Aalto's cletailing
at the I?iimio Sanitoriuin ; I S ;I superh
esample. The photograph c\xs taken in
1968mlien the original finishes n ~ etill
intact. Another Lwsion of the concept
could be made by using pre-cast terrazzo
to the strings t o recei\,e the railings, \\sit11
the flights also pre-c;ist with terrazzo tilr
finislies (Figure8.Sh).
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Concrete stairs 147
P lan detail forminimum scheme
Handrail and
1over top and bottom
Vertical step
handrail to R H
Preferred line at soffit (XX)
Better solutionwith staggeredrelation to riserand neat soffits line i l l)
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148 Stairs
Note reinforcementto NIBS tied to mainbars
Radius work
Alternative Birds mouthbeam profile bearing joint
for lower
flight Identic; unitsfor dog-leg flights
Curved rakingline for handrailand string
(9 \ -7 --,
Width equal
to tread
{{I :/P
Swept curveto handrailand lining
Half tread moved
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Concrete stairs 149
Core rail
Balustrade zoneplaced externalto concrete stairs
Continuous4 411.*.
*Y
steel tubular I 1mullions
Circular
handrail run 1 l wwithin stairspace I l l 1 I I
I Infilling
wellinimalf 1OOil25 ~ - ~m(between ha1
Ideal if
gmension
RC fender beam
Handrailing -and bracketsplaced externalto fender
plan (tread
diameter)givesperfectsweepto wreathing
60 to
70 clear oftender
idrail)
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150 Stairs
Note set screwsTubular rail on underside
Hardwood mop stick
10 x 40 steel core rail
25 rnrn tubular railswith internal sleevedTapered 12.5 X 60
steel standards
10 x 60 x 120base plate (welded)
handle varyingguarding level ofhandrail
Tile bed and screed
Texture paint finish
l . ' / <y / / l ~ [ J.517 f i ~ l l t l < J l .l l / ) l F l ~ ~l . Y / ( ~ l ' t Y I : ~ o
usually