Half turn stair These stairs are common in

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 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. 15 m to 1 m 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 12 cm.

NOW WE ARE GOING TO SEE 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 jurg. Conzett 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 Mc. Rae, 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 Long champ 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 16 th 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 16 th 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 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 = √(Span 2 + Height 2) When the flight is built monolithically into members spanning at right angles to its span, the effective span is given by: la = 0. 5(lb 1 + lb 2) where la = clear horizontal distance between supporting members lb 1 = Breadth of supporting member at end 1 but ≤ 1. 8 m lb 2 = 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 / √(rise 2 + going 2) + 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 k. N/m 2 and ≤ (100 psf) 5 k. N/m 2. 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 wl 2/10 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 wl 2/8. 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 F 1/ 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