Half turn stair
• These stairs are common
in residential and public
building.
• These are having
direction reversed or
changed by 180 degree.
• These are of two types:
dog legged stair & open
newel stair.
Dog legged stair
• Newel post are
provided at the
beginning and end
of each flight.
• There is no space
between two
flights.
• A half spaced
landing is provided
generally to affect
the change in
direction.
These components are reinforced with steel that give stability to the
structure. Staircase is one such important component in a RCC structure.
Dog Legged Stair
In this article, we will discuss different
types of staircases and study the RCC
design of a dog-legged staircase…
Stairs
Stairs consist of steps arranged in a series
for purpose of giving access to different
floors of a building. Since a stair is often
the only means of communication
between the various floors of a building,
the location of the stair requires good and
careful consideration.
In a residential house, the staircase may
be provided near the main entrance.
In a public building, the stairs must be
from the main entrance itself and located
centrally, to provide quick accessibility to
the principal apartments.
Open newel stair
• Space of width
0.15m to 1m is left
between two
parallel flights.
Bifurcated stair
• Used in public building at
or near the entrance hall.
• Wider flight from the
bottom bifurcate into two
narrower flight one
towards right and other
towards right at the
landing.
Continuous stair
• It do not have
intermediate newel post
or landing.
• These stairs may be of
circular, helical or spiral in
shape.
• These are emergency
stairs.
Material for stair construction
• These may be constructed of timber, steel,
stone, RCC and bricks.
• RCC commonly used for residensial or public
building.
• RCC stairs are of two types:
Stair with slab spanning longitudinally Stair
with slab spanning horizontally
the slab is supported at
bottom and top of the
flight and remain
unsupported on sides.
Stair with slab
spanning horizontally
• The slab is supported by
wall on one side and
stringer beam on other
side.
• Thickness of slab vary
between 8 to 12cm.
10 CRAZY STAIRS FROM
AROUND THE WORLD
ADMIN
Stairs and staircases have been a
engineering marvel since the start of
the multi story architectural designs.
But now in this modern era
engineers have taken designing to its
utmost limit, here are some of the most
amazing staircases from around the
world. Top 10 crazy stairs.
TRAVERSINERTOBEL SWITZERLAND BRIDGESTAIR
In traversinertobel Switzerland you will find an amazing
Bridge-stair on a side valley of Via Mala, it is one of its
kind amazing staircases from around the world, designed
by Engineer jurgConzett and his associate Rolf Bachofner.
The main engineering problem they faced was the
problem of connecting two different elevations over the
gorge by creating a staircase. The staircase replaces a
rope bridge for hikers that was wiped out by a rock slide.
This suspended footbridge spans a distance of 56 metres,
with a difference in height of 22 metres between the two
ends.
Vertigo Staircase at the Queen Victoria
Building Australia
“The Grand Staircase" of Sydney's Grand Queen Victoria Building
Australia is affectionately known as the QVB, was designed and
completed 1898 by George McRae, replacing the original Sydney
markets on the site. Built as a monument to the long reigning
monarch, construction took place in dire times, as Sydney was in a
severe recession. The elaborate Romanesque architecture was
specially planned for the grand building so the Government could
employ many out-of-work craftsmen – stonemasons, plasterers,
and stained window artists – in a worthwhile project.
Long champ Store
stairs at New York
It took six months and 1.14
inches of ho rolled steel to
build the stairs at Longchamp store, these stairs
weight 55 tons and is has
a ribbon like form which
give wave look. They divide
and converge to form a
topography of walkways,
landings and steps.
Umschrei bung – KPMG
Building Munich
(Germany)
This amazing staircase are
actually functional and not just
a design. Designed by Olafur
Eliasson this staircase is called
Umschreibung (Rewriting), and
was completed in 2004. It's in
the courtyard of the global
accounting firm KPMG in
Munich.
World's Longest Mosaic Stair the San
Francisco's Tiled Steps (USA)
This could be the world's longest mosaic staircase (163
steps, 82' high) the 16th Avenue Tiled Steps, are , was
conceived and fabricated by Irish ceramicist Aileen Barr
and San Francisco mosaic artist Colette Crutcher. It took
about 2 and half years of hard work by a group of
neighbors who raised funds and lobbied city government
to make the project, unveiled in August 2005, a reality.
Over 2000 handmade tiles and 75,000 fragments of tile,
mirror and stained glass went into the finished piece,
located at 16th Ave. and Moraga, in San Francisco.
The Lello Bookshop Staircase
at Portugal
The amazing grand staircase at Lello
Bookshop in Portugal is one its kind. The
steps of this staircase are like two channels
pouring and swirling to a single point. The
side view gives you a closer idea of the
immense curves and giddy sinking feeling
to each step.
Tulip Staircase design from Queen's House England
This beautiful architecture of Tulip Stairs can be seen at the Queen's House
it is the first geometric self-supporting spiral stairs in Britain. Although called
the 'Tulip Stairs,' it is thought that the stylized flowers in the wrought-iron
balustrade are actually fleurs-de-lis, as this was the emblem of the Bourbon
family of which Queen Henrietta Maria (wife of Charles I) was a member.
The Tulip Stairs are also the location of the Rev R. W. Hardy's famous 'ghost'
photograph taken on 19 June 1966, which when developed revealed what
appear to be two or three shrouded figures on the staircase.
Loreto Chapel Staircase at New Mexico US
The Loreto Chapel is a chapel in Santa Fe, New Mexico, is a spiral staircase
that is an artistic work of carpentry and engineering. The construction and
builder of the staircase are considered a miracle by the Sisters of Loreto and
many who visit it, because it had no central support (a support was added
later). The resulting staircase is an impressive work of carpentry. It ascends
twenty feet, making two complete revolutions up to the choir loft without the
use of nails or apparent centre support. It has been surmised that the central
spiral of the staircase is narrow enough to serve as a central beam.
Nonetheless there was no attachment unto any wall or pole in the original
stairway. Instead of metal nail,the staircase was constructed using dowels or
wooden pegs. The wood for the staircase cannot be found anywhere in the
region. The stairs had 33 steps, the age of Jesus when he died. The mystery
had never been satisfactorily solved as to who the carpenter was or where he
got his lumber, since there were no reports of anyone seeing lumber delivered
or even seeing the man come and go whilethe construction was being done.
Since he left before the Mother Superior could pay him, the Sisters of Loretto
offered a reward for the identity of the man, but it was never claimed.
The Spiral Staircase at the Vatican Museum (Italy)
The Vatican Museums spiral staircase is one of the most
Photographed staircases in the world, and certainly one
of the most beautiful. Designed by Giuseppe Momo in
1932, the broad steps are somewhere between a ramp
and a staircase. The stairs are actually two separate
helixes, one leading up and the other leading down, that
twist together in a double helixformation. Little did the
Vatican Museum know in 1932 that this formation would
come to represent life itself, with the discovery of the
double helical DNA strand.
Spiral Stair
(Australia)
This amazing staircase
is located at Garvan
Institute in Sydney,
Australia. 6.5 revs and
five stories from top to
bottom white paint and
lights. The six storey
staircase is the showpiece of the Garvan
Institute of Medical
Research in Australia. Its shape
reminds me of a DNA helix,
and its clean white colour, glass
sides and chrome railings the
facility’s medical function. The
six levels of the structure are also
featured in the fantastic domecovered atrium.
Basics about Stair Slabs
Types: There are two types of stair flights, classified on
the direction of span:
1. Transverse: The steps may be supported on both
sides, or may be cantilevered from an adjacent wall,
for example.
2. Longitudinal: The stair flight spans onto landings or
beams at either end of the stair flight.
Design of Transverse Stairs: Design of these sections
are based on the average effective depth of the
section. These flights may cantilever from a wall or
span from a wall to a stringer beam, for example.
• Design of Longitudinal Stairs: The design of these
stairs is more complicated. The additional factors to
consider are:
Basics about Stair Slabs
1. Geometry:
Given the rise, going and the number of steps, the span and overall height rise can
be determined:
Span = (No. Steps – 1) × going Height = No. Steps × rise
Slope Length = √(Span2 + Height2)
When the flight is built monolithically into members spanning at right angles to
its span, the effective span is given by:
la = 0.5(lb1 + lb2)
where la = clear horizontal distance between supporting members
lb1 = Breadth of supporting member at end 1 but ≤ 1.8 m
lb2 = Breadth of supporting member at end 2 but ≤ 1.8 m
Basics about Stair Slabs
Loading:
The dead load is based on the slope length of the stair flight. The average
thickness of the stair slab is used to calculate the dead load:
h = 0.5 × rise × going / √(rise2 + going2) + waist + finishes
Finishes are included as they are generally assumed to have a density equal to that of
concrete.
The live load is based on the plan area of the stairs and is to be taken as the same
to the floor which the stairs give access, but ≥ (60 psf) 3 kN/m2 and ≤ (100psf)
5
kN/m2.
If two stair flights, at right angles, share a landing, the landing loads may be
assumed to be divided equally between the spans. As part of the landing may be
considered as part of the stair flight, the loading on the landing must be taken into
account in the shear check.
Design: Flights with significant end restraint, such as those that are continuous with their
supporting slabs or beams may be designed for mid-span design moment of wl2/10 and
hogging moment at the supports of the same value. Where there is not sufficient end
restraint the stair slab is to be designed for wl2/8.
The maximum shear should be ascertained from a simply-supported model of the
stair slab. When the stair flight (on plan) occupies at least 60% of the effective span, the
permissible span/d ratio may be increased by 15%.
Detailing:
The reinforcement arrangement in stair flights follows a standard pattern.
Deviation from this is not recommended unless a specific need arises.
Longitudinal steel is the main reinforcement and in the transverse direction the
minimum percentage of steel is provided as “distribution steel” to help prevent cracking.
Strength requirements are not always critical for stair slabs. It is therefore
essential that the other limit states are checked:
a. Deflection
b. Cracking
c. Min % As
• The usual form of stairs can be classified into two types: ( 1) Those spanning
horizontally in the transverse direction, and (2) Those spanning longitudinally.
-Stairs of this type may be supported on both sides or
they may be cantilevered from a supporting walls
-Figure shows a stair supported on one side by a wall
and on the other side stringer beam. Each step is
usually designed as having a breadth b and an effective
depth of d = D/2 as shown in the figure;
-Distribution steel in the longitudinal direction is placed
above the main reinforcement.
-Details of a cantilevered stair are shown in figure The
effective depth of the member is taken as the mean
effective depth of the section and the main
reinforcement must be placed in the top of the stairs
and anchored into the support.
A light mesh of reinforcement is placed in the bottom
face to resist shrinkage cracking.
Stair Slab Spanning Longitudinally
• The stair slab may span into landings which
span at right angles to the stairs as in Figure a
or it may span between supporting beams as in
figure b
Design of Stair slab
• The dead load is calculated along the slope length of the stairs but the live load I,
based on the plan area. Loads common to two spans which intersect at right
angles and surround an open well may be assumed to be divided equally between
the spans. The effetive spa n (I) is measured horizontally between the centres of
the supports and the thlckness of the waist (h) is taken as the slab thickness.
• Span-effective depth ratios may be increased by fifteen per cent provided that the
stair flight t occupies at least 60 per cent of the span.
• Stair slabs which are continuous and constructed monolithically with their
• supporting slabs or beams can be designed for a bending moment of say F1/
10.where F is the total ultimate load. But in many instances the stairs are precast
or constructed after the main structure, pockets with dowels being left in the
supporting beams to receive the stairs , and with no appreciable end restraint the
design may be done by Fl/8
Design Example