BUILDING CONSTRUCTION

STAIRS AND STAIRCASES Stairs : “It’s a series of steps suitably arranged for the purpose of connecting different floors of the building.” General specification about stairs Should be locate at centre of building geometry Should be near to the entrance Sufficient amount of stairs incase of huge geometry Location such that ease to reach and at lesser time from any part of the building Material used in stairs must be fire resistive and non corrosive Staircases : “ enclosure of the building in which stair is located”

Technical terms of stairs their specifications:

Technical terms of stairs: Step: a single unit composed of Rise and Tread Tread: Upper flat portion of step upon which the foot is placed for ascending or descending Riser: vertical portion of step providing support to the tread Rise: the vertical distance between two successive tread facing Going: horizontal distance between two successive riser faces Baluster: vertical member of wood or metal, supporting the hand rail Balustrade: combine frame work of railing and baluster , used to provide protection to the user Hand rail: molded member of wood or metal, used to providing assistance and safeguard to person while going over stair Flight: a series of steps without an intermediate platform Landing: flat platform at the top and bottom of the flight , used to change direction and for taking rest

Technical terms of stairs: Nosing: protecting edge of tread Pitch or slope: An angle which the line of nosing made with floor String: these are the sloping members which support the steps Scotia: A molding provided under the nosing to improve the elevation of the step, and provide strength to nosing Waist: thickness of structural slab in case of stair made up of R.C.C Newel post: These are principal posts supporting a hand rail, placed at the ends of flights to connect the ends of strings and hand rail. Head room: minimum clear vertical distance between the tread and over head structure i.e. ceiling etc. Run: total length of stair in a horizontal plane, including landings Header: horizontal structural member supporting stair strings or landings.

Figure: Flight and Head room of stair Technical terms of stairs their specifications: Figure: Flight and Head room of stair

Technical terms of stairs their specifications: Figure:

Technical terms of stairs their specifications: Figure: Flight should be divide if its width more than 1.8 m

Requirement of good stairs: Location: Sufficient light and ventilation should be available Should be Easy to access Should be located centrally on building geometry Material: Good quality (Strength, Fire resistance) and should be constructed with good workmanship Width of Stair: Should be sufficient width and at least 1m in residential building and more than one meter in case of public building Length of flight: Not more than 12 steps and not less than 3 steps in single flight Pitch of stair: Should not more inclined Head room: should not less than 2 to 2.3m Step Dimension: Going or tread : should not less than 25cm Rise: should not more than 15cm The width of landing should not be less than the width of stair.

Types of Steps in stair: Flier: Ordinary rectangular step Bullnose : Situated at the bottom of flight and having one or both end of step rounded Round ended: same as bullnose but the top view is semicircular Splayed step: Provided at the beginning step with tapered face Commode Step: Curved riser and tread Dancing step: Horizontally inclined step Winders: Tapering step, usually provided when less space availability, Winders should be avoid in public building

Types of Steps in stair:

Classification of Stairs Straight stair: Having one single flight or numbers of straight flights Turning stair: Turning stair further classified as Quarter turn stair: Newel Quarter turn Geometrical quarter Half turn stair: Dog-legged or Newel Half turn Open newel half turn Geometrical half turn Three quarter turn stair Bifurcated stair Spiral stair Helical Stair

Types of Stair : Straight Stair Straight Stair: Plan Straight between two floors Continuous in one direction Single or may be more than one Used for Small houses where narrow space is available.

Types of Stair : Newel Quarter Turn Stair It is used when the direction of flight is changed at right angles to the left or right. Plan Sectional Elevation Newel Quarter Turn Stair Newel post at the beginning and at the End of each flight The quarter turn may be of winders or space landing

Types of Stair : Geometrical Quarter Turn Stair Commonly provided at the backside of the building for providing entry at various floors. Plan Geometrical Quarter Turn Stair Strings as well as hand rail is continuous No newel post at the Landing Having circular shape in plan.

Types of Stair : Dog-Legged Stair Quarter space landing It is used when length of staircase is restricted and width is such that only two flight is accommodated Dog-Legged Stair Quarter space landing: plan Consists of two Straight flight of steps with abrupt turn between them The direction of the flight is turned by 180’ There is no space between two flights.

Types of Stair : Open Newel Half Turn Stair Plan Open Newel Half Turn Stair: plan This type of stairs are used at places where sufficient space is available to accommodate a third flight having three to four steps. Same as Dog-legged but its having space between two flights.

Types of Stair : Geometrical Half Turn Stair Geometrical Half Turn Stair: plan Continuous hand rail without any breakup May have half space landing or without landing

Types of Stair : Bifurcated Stair Bifurcated Stair: plan Common in public building at their entrances hall. Wide flight at the beginning and narrow flight when it turns in both the direction

Types of Stair : Spiral Stair Top view circular with single centre of curvature Generally made up of R.C.C or Steel This type of stairs are used, where space available is to small and the traffic is less. Also used as a emergency stairs and provided at the backside of the building. Circular Stair: plan

Types of Stair : Helical Stair This stair looks very fine. The structural design and construction is very complicated. It is made of RCC ,steel and wood. Helical Stairs: plan

Fabricated Stair : Timber: Used in residential buildings and at small shops Light weight Used when fire resistance criterion not important Built on place or at shop Timber used for stair should be free from termite, well treated Metal Mild steel or cast iron used Used for factory, godowns, workshops Not used for residential and public building They creates noise Not good appearance Pre-Cast concrete: Ready made cast available in market

Elevators or Lifts: “It is the Appliances designed to transport persons or materials between floors in vertical direction by means of guided vertically movable platform” Two basic system :1) Counter weight suspension 2) Electrically motors Types of Lifts: Passenger lift: For moving human being Goods lift: For material transport Having loading and unloading facilities Hydraulic Elevator or Lift For Low rise buildings Electric lift For tall buildings

Design Criterion/Consideration for Lift Numbers of lift block, its size, position in building geometry Particulars of lift block enclosure Lift door Number of floors or vertical distance for lift Height between floor levels Total headroom Numbers of entrance Numbers of passengers to be handled And of course the weight carrying capacity

Suitability of Types of Vertical Appliances GTU- June-2010 Dog-legged stair: When need to sudden change of direction while vertical movement of human Being Elevators or Lift: More than four storey for moving people and materials Ramps: when larger numbers of people or vehicle are to be moved from floor to floor e.g. Garage, railway station, stadium etc. Escalators: Where traffic is heaviest and convenient for passengers when large numbers of persons to move from floor to floor, Generally provided at shopping mall, public building etc for the architectural point of view used to guide people towards main exits. Also speed should be changed based on current of motors. Inclination angle is 30 degrees.

Ex :- Plan of stair of building in which the vertical distance between the floors is 3.74 m. The stair hall measures 5.00*2.40 m . Ans :- 1) take rise 17 cm and tread be 27 cm. 2) Let us keep width of each flight = 1.15 m 3) Width of landing = width of stair = 1.15 m 4) Height of each flight = 3.74/2 = 1.87 m 5) No. of risers required = 1.87/17 = 11 in each flight 6) No. treads in each flight = 11-1 = 10 7) Space occupied in treads = 10*27 = 2.70 8) Space left for passage = 5.0 – 1.50 – 2.70 = 1.15 m ok

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