# Staircase

The staircase is an architectural construction made up of a regular succession of steps, the degrees, giving access a stage, to pass from a level to another while going up and going down.

A staircase can be out of stone, wood, metal, concrete, glass.

Its structure is intégréee with the wall which supports it, that is to say an assembly independent of the remainder of the Carcass work heavy castings and the assembly is a monopiece work. The staircase is of a very variable complexity of design: concrete straw mattress, kind of crawling flagstone comprising the steps and posed into uneven, of the simple stacking of the steps out of metal which can give the staircase in system to screw with core, to the stone winding staircase on vault sarrasine and the balanced wood or cut stone staircase with central day.

The staircase can be with right or circular or mixed rise: right or to Italian, helicoid or with screw or out of snail or radiant, balanced or with the Frenchwoman or revolving districts.

The professional who manufactures and poses the staircases, when they are in Bois is the more specialized Charpentier than the Menuisier.

## Calculation

In 1675, François Blondel considers the question of the calculation of the staircase in its Cours of architecture taught to the royal Academy of architecture . It measures the not (within the meaning of distance crossed by the foot at the time of a normal walk on a horizontal level) and notes that “with each time one rises of a inch, the value of the horizontal part is reduced by two inches and that the sum doubled height of walk and its bosom must remain constant and be two feet”.
In other words: $M = 2:00 +g$, where $M$ is the module (or the step) and is worth 2 feet (64,8 cm), $h$ the height of walk, and $g$ its bosom (distance between two consecutive edges of step measured on the line of tread).

The guiding idea is that the effort made by the person who goes up is constant, in spite of the variations height assembled indeed compared to horizontal displacement according to the place where one is located in the staircase, stronger rise in the elbows, (this person is positioned with the hand on the slope).

Nowadays , the current steps has 17 cm of height and 28 cm of bosom: the usual step is of 63 cm (the place, and consequently the importance, attached to the staircase are less than at the 17th century), the slope of these steps is of 30° approximately. This standard value is to be regarded as bases calculation, all is question of the effect to give to the staircase (escarpé, or on the contrary pleasant).

## Current angles of slope

The angle of the talus of the staircases is distributed as follows:

• a: crawls (of 0 with 24°)

• a: crawls soft (of 0 with 6°)
• b: crawls normal (of 6 with 10°)
• C: strong slope (of 10 with 24°)
• b: staircase running (of 24 with 45°), the maximum value is of 40° in the public places and 45° in the dwelling. The current price (and thus most comfortable) is around 30°.
• C: staircase of machine (of 45 with 75°)
• D: scale (of 75 with 90°)

## Terminology

; Stair-well: Part in which the staircase is (without the staircase being necessarily leant with its walls called walls of string wall). ; String wall, wall of string wall: wall on which the staircase rests. ; Flown: Portion of staircase lain between two platforms and which includes/understands the steps. The steps are right (in parallel) in the right flight, the steps are radiant in the flight of stairs to screw (with the Frenchwoman), the steps oblique or are balanced or dancing in the revolving districts. ; Stage: Platform spared on the floor reaching the landing doors, the main bearing . The intermediate platform is called rest or stage of rest and does not give access to buildings. ; Day: Vertical space left by the flights, empties central in the stair-well. ; Smooth (or handrail): It belongs to the Garde-corps and it accompanies the staircase over all its length. ; Escaped: Height of passage, catch vertically between the edge of step and the lower part of the floor or of flown to the top (mini: 1,90  m; generally: 2,10  m). ; Go: Degree, horizontal part on which one poses the foot. Walk is defined dimensionally by its emmarchement, its bosom and its height. Formally a walk can be: right or square (if it is rectangular); balanced or dancing if the two ends have different widths; oblique so without being balanced it is not perpendicular to the silt. The walk of bottom is the walk starting , that the top is the walk of arrival or landing walk . ; Parts of walk:
Walk : Horizontal surface on which one poses the foot.
Edge of step : left projecting walk on the naked one of the contremarche, the height of the guard body or the handrail is calculated starting from the nose.
Collet : small side of a balanced walk.
Contremarche : Vertical part between two steps. The contremarche is making safe, however it is not systematic (the scales of miller do not have any, for example).
; Straw mattress: In the case of the concrete staircases, it is the inclined flagstone integrating the steps of a flight. ; Silt: Sill, beam which makes it possible to hold the stairs.
For the stone staircases, the silt is not a sill, it has an esthetic function and is autonomous in its structure just like a Arc-boutant can the being.

## Regulation in the public places

### Width of passage

• the French regulation of safety of the establishments receiving from the public (ERP) defines the concept of unit of passage (UP):
1 unit of passage is equivalent to a width of passage of 0,60  Mr.

Exceptions:

• Only one unit of passage is worth 0,90  Mr.
• Two UP are worth 1,40  Mr.
• One finds the value of 0,60  m starting from 3  UP: 1,80  m and so on.

### Keep body

General rules for the private individuals
• Guard crawling body:
Un guard crawling body is keeps it body which follows the flight of stairs. This one must always be envisaged a height of 0,90  m (900  mm) minimum compared to the edge of step.
• Guard of bearing standard:
Un guard bearing standard is intended for the parts horizontal of a staircase. This one must always be envisaged with a height minimum of 1m (1020  mm generally). One finds obligatorily a plinth, generally located at 50  mm of the ground and which goes up until 450  minimum mm, followed number of smooth wished to obtain 1020. The maximum spacing of those must be of 180  Misters

General rules for the industrial facilities
Le case of the industrial facilities holds a little different standards. In the case of access to the machines (generally in industrial sites) an European standard envisages a height minimum of 1,10  m with a plinth on a height of 10  cm with the bottom of the railing. The railing must have a resistance in sufficient horizontal pressure to retain a person.

### Stages

• the stage is the platform which receives the flights of stairs going up and going down and gives access on the floor by the landing doors.
• right Staircases or turnings:
Une flown of steps cannot exceed 25 steps. If that is the case, of the platforms known as rest must be registered between two flights in the staircase. The flights can be unequal.
• helicoid Staircases:
Il should not have there other platforms only those serving the stages.

## Escalator and scale

The Escalator or escalator (mark) is a conveyer with the mobile steps and the scale a skeleton.

## Special staircases

There exist special staircases, like:

• the Japanese Staircase or Staircase with Japanese step or Staircase with shifted steps.

## Famous staircases

### Staircase with double helix

The staircase of the Château of Chambord is built on the basis of drawing of Léonard de Vinci with the characteristic to be made up of two staircases in one. The two propellers are overlapping one in the other without communication, even visual. A person can thus go down and another to go up without never crossing. The archicturaux elements of this staircase are inspired by the staircase of the Château of Blois

### Monumental staircase of Michel-Angel

Michel-Angel, architect, designs the staircase of the Bibliothèque laurentienne which makes it possible to connect it to the convent of the church San Lorenzo of Florence.

### Staircase of the Palate of the Cannes festivals

The staircase of the Palais of the festivals is famous for the “rise of the steps” of the stars of the cinema at the end of spring, at the time of the opening of the international festival of the film to Cannes.

### Infinite staircase

Imagined by the mathematician Penrose. It is about a Optical illusion in the category of the impossible objects.

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