STAIRS

Type Of StairsWoodBrickStoneSteelConcreteCombination of the materials

Characteristic Of StairsNon-combustible materialsComfortableSafety follow the rules Stairway protected by a fire-resisting enclosure.Limitations as to riser height, tread lengths and handrail requirement usually based upon use the building

Single Straight Flight Stairway

Simple in design and construction, can be unpopular because of the plan space it occupies.The flight behaves as a simply supported slab planning from landing and landing.The effective span or total horizontal going usually taken as being from landing edge to edge by providing a down stand edge beam to each landing.Edge beam are not provided the effective span would be taken as overall of the landing.Resulting in a considerably bending moment and hence more reinforcement.

Inclined Slab Stair With Half-Space Landing

Usually plan format for reinforcement concrete stair giving a more compact paln layout and better circulation than the single straight flight stairs.The haft space(180°)turn landing is usually introduced at the mid-point of the rise giving equal flight spans.Reducing the effective span and hence the bending moment considerably.Design the landing span crosswise into a load bearing wall.Tension lap required at the top and button of each flight to overcome the tension included by the tendency of the internal angles of the junction.

Staring Beam Stairs

Alternative design for the stairs described above.Edge beam is used to span from landing to landing to resist the banding moment.Result in a thinner waist dimension and an overall saving in the concrete volume require.The staring beams can be either up stand or down stand in format and to both sides.

Cranked Slab Stairs

Very often used as a special feature since the haft space landing has no visible support. Bending, buckling and tension stress are included with this form of design creating the need for reinforcement to both faces of the landing.Slab or waist of the flight, indeed the amount or reinforcement require can sometimes create site problem with regard to placing and compacting the concrete.Typical details of a cranked slab stairs, which is also known as continues stairs, scissor stairs or jack-knife stairs.

Cantilever Stairs (Spine Wall Stairs)

Central vertical wall from which the flight and haft space landing are cantilever.The wall provides a degree of fire resistance between the flight and are therefore used mainly for escape stairs.Since both flight and landings are cantilever the reinforcement is placed in the top of the flight slab.Upper structure of the landing to counteract the induced negative bending moments.

Spiral Stairs

Used mainly as accommodation stairs in the foyers of prestige buildings such as theatres and blanks.Can be expensive to construct, being normally at least seven times the cost of conventional stairs.The plan shape is generally based on a circle although it is possible to design.Can be formed around a central large-diameter circular column in a similar manner.Tension and compressive stresses are included in this form of stairs way which will require reinforcement to both faces of the slab.Formwork for spiral stairs consists of a central vertical core or barrel to form the open stairs well to which the so fit and riser boards are set out and fixed.

Precast concrete stairØ  Better quality control of the finished product.

Ø   Saving in site space, since formwork storage and fabrication space are no longer necessary.

Ø  Stairway enclosing shaft can be utilized as a space for hoisting or lifting materials during the major construction period.

Ø  Can usually be positioned and fixed by semi-skilled operatives. 

Precast Concrete Straight Flight Stairs.

Ø   Spanning between landing can have a simple bearing or, by leaving projecting reinforcement to be grouted into preformed slots in the landings.

Ø  Straight flight precast concrete stairs with a simple bearing require only bottom reinforcement to the slab and extra reinforcement to strengthen the bearing or nib.

Ø   The bearing location is a rebate cast in the in-situ floor slab or landing, which is filled with a compressible material to form a flexible joint.

CRANKED SLAB PRECAST CONCRETE STAIR

Ø   Usually formed as an open well stairway.Ø   The bearing for the pre-cast landings to the in-situ floor or

to the structural frame is usually in the form of a simple bearing

Ø   The infill between the two adjacent flight , in an open well plan arrangement at floor and intermediate landing levels.

Ø   It must be remembered that when pre-cast concrete stair flight are hoisted into position, different stresses may be included from those which will be encountered in the fixed position.

Ø    To overcome this usual ,provide definite lifting points in the form of the projecting lugs or by utilizing any holes cast in to received the balustrade.

 

Precast Concrete Open Riser Stairs.

   Are a form of stairs which can be both economic and attractive consisting of a central spine beam in the form.

Ø    The foot of the lowest spine beam is located and floor levels.

Ø    Anchor bolts or cement in sockets are cast into the spine beam to provide the fixing for the cantilever.

Ø    The support for the balustrade and handrail are located in hole formed at the ends of the treads and secured with a nut and washer on the underside of the tread.

Precast Concrete Spiral Stairs.

Ø  Work are based upon the stone stairs found in many historic buildings such as Norman castle and cathedrals.

Ø  Holes are formed at the extreme ends of the treads, to receive the handrail supports in such a manner that the standard passes through a tread and is fixed to the underside of the tread immediately below.

Ø  A hollow spacer or distance piece is usually incorporated between the two consecutive treads.

Steel Escape Stairs .

Ø  These have already been considered in the context of means of escape in case of fire and a typical general arrangement is illustrated.

Ø   The treads for this type of stair are bolted to the strings and can be of a variety of types ranging from perforated cast iron to patterned steel.

Ø   Handrail balustrades or standards can be of steel square or tubular sections bolted to the upper surface of a channel string or to the side of a channel or steel plate string.

Steel Spiral Stairs .

Ø  These may be allowed as an internal or external means of escape stairs if they are to accommodate no more than 50 persons.

Ø  Spiral stairs give a very compact arrangement and can be the solution in situations where plan area is limited.

Ø  Two basic forms are encountered, namely those with treads which project from the central pole or tube and those which have riser legs.

OTHER STAIR

CONCLUSION.Have so many type of stairs, for example wood,

brick, stone, steel, Concrete and Combination of the material. This type will be design with follow the place where the stair erected. The main function of stairs is for give easily to user for up and down in the building. Good characteristic that usually have in stairs is Non-combustible materials, comfortable, safety follow the rules, stairway protected by a fire penetration and limitations as to riser height, tread lengths and handrail requirement usually based upon use the building.