Building Construction Lecture Notes PDF

AJMAN UNIVERSITY College of Architecture, Art, and Design Building Construction ARC 233 Stairs & Elevators Related CLO’s: CLO 4,...

AJMAN UNIVERSITY College of Architecture, Art, and Design Building Construction ARC 233 Stairs & Elevators Related CLO’s: CLO 4, CLO 6 Raghad Mourad Stairs provide means for 1- moving from one level to another and are 2- therefore important links in the overall Staircases & Elevators circulation scheme of a building. Whether punctuating a two-story volume or rising through a narrow shaft, a stairway takes up a significant amount of space. The landings of a stairway should be logically integrated with the structural system to avoid overly complicated framing conditions. Safety and ease of travel are, in the end, the most important considerations in the design and placement of stairs. Multistory buildings require elevators to move people, equipment, and freight from one floor to another. For accessibility to multistory public and commercial facilities by persons with disabilities, federal regulations mandate their installation, An alternative to elevators is the escalator, which can move a large number of people efficiently and comfortably between a limited number of floors. Functional requirements: Some of the major functional requirements of the staircase are: Stability :Staircases are required to carry the loads of people and objects without excessive deflection protection from fire Approved in the Building Regulations requires fire escape protected stairways and landings to be constructed with ‘materials of limited combustibility’. suitable dimensions; The dimensions adopted for stairways affects their ease and safety in use. appearance. Stairs are a complex item of building structure and very careful attention is essential to such details as: junctions between skirting board and wall strings; profiles and junctions of handrails, strings, newels and balusters. The detailing of finishes for treads, risers and nosing (particularly with concrete stair).  Stair Terminology 1. Stair Terminology Stairs A-The dimensions of risers and treads in a stairway should be addeG proportioned to STAIR DESIGN accommodate our body movement. The pitch if steep, 1 can make ascent physically tiring as well as psychologically forbidding, 2 and can make descent unsafe. If the pitch of a stairway is shallow, its treads should be deep enough to fit our stride. B-Building codes regulate the minimum and maximum : dimensions of risers and treads: The riser and tread dimensions can be proportioned according to either of the following formulas: Tread (inches) + 2x riser (inches) = 24 to 25 Riser (inches) x tread (inches) 72 to 75 C-Exterior stairs are generally not as steep as interior stairs, especially where dangerous conditions such as snow and ice exist. D-For safety, all risers in a flight of stairs should be the same rise and all treads should have the same run. 1-The actual riser and tread dimensions for a set of stairs are determined by dividing STAIR DESIGN the total rise or floor-to-floor height by the desired riser height. 2- The result is rounded off to arrive at a whole number of risers. 3 The total rise is then redivided by this whole number to arrive at the actual riser height. 4 This riser height must be checked against the maximum riser height allowed by the building code. 5 If necessary, the number risers can be increased by one and the actual riser height recalculated. 6 Once the actual riser height is fixed, the tread run can be determined by using the riser:tread proportioning formula. Since in any flight of stairs, there is always one less tread than the number of risers, the total number of treads and the total Maximum riser height; minimum run can be easily determined. tread depth for accessible stairs and emergency egress  Stair Requirements Stairway design is strictly regulated by the building code, especially when a stairway is an essential part of an emergency egress system why?. because an accessible stairway should also serve as a means of egress during an emergency, stairway width The occupant load, which is based on the use group and the floor area served, determines the required width of an exit stairway. (1120) minimum width: Handrails may project a maximum of(115) into the required width:  Stair Requirements Landings Landings should be as least as wide as the stairway they serve and have a minimum length equal to the stair width, measured in the direction of travel Door should swing in the direction of egress. Door swing must not reduce the landing to less than one half of its required width. When fully open, the door must not intrude into required width by more than (180). Handrails Handrails are required on both sides of the stair. The building code allows exceptions for stairs in individual dwelling units. (665 to 965) height above the leading edge of the stair treads or nosing. Handrails should be continuous without interruption by a newel post or other obstruction. The ends should return smoothly to a wall or walking surface, or continue to the handrail of An adjacent stair flight. Guardrails 1 Guardrails are required to protect the Stair Requirements open or glazed sides of stairways, ramps, porches, and unenclosed floor and roof openings. 2Guardrails should be at least (1070) high: guardrails in dwellings may be (915) high. 3Guardrails protecting the open or glazed side of a stairway may have the same height as the stair handrails. A (100) sphere must not be able to pass through any opening in the railing from the floor up to (665): from (665 to 1070), the pattern may allow a sphere up to 8 diameter to pass. 4- Guardrails should be able to withstand a concentrated load applied to their top rails in both vertical and horizontal directions. Treads, Risers, and Nosing A minimum of three risers per flight is recommended to prevent tripping and may be required by the building Guardrails: Guardrails shall be installed on all open sides of stairways, porches, balconies, or raised floor surfaces more than 30 inches above floor or grade below. Minimum height of the guardrail shall be 36 inches. Handrails that form a guard at the open side of a stair shall be 34 – 38” in height, measured from the nosing. Balusters or ornamental closures must be of a design, which will not allow a 4-inch sphere to pass through. Balusters or ornamental closures on stairs must be of a design, which will not allow a 4-3/8-inch sphere to pass through. Horizontal rails or other patterns with a ladder effect are not permitted. Stairs: 7-3/4” Rise (Max), 10” Run (Min), ¾” Nosing (Max). Handrails: A handrail is required on at least one side of each stairway with four or more risers. (34 min. to 38 max.) Shall be continuous for the full length of the stairway. Ends shall be returned or terminated in newel posts or safety terminals. Minimum clearance of 1-1/2 inches between wall and handrail is required. Circular cross section with diameter of 1-1/4 to 2 inches for handrail is required. Noncircular cross section with perimeter between 4 inches and 6-1/4 inches and maximum cross section of 2-1/4 inches is permitted. Edges of handrails should have a minimum radius of 1/8 inch. ADA Accessibility Guidelines Handrails Accessible stairs should also serve as (1) a means of egress during an emergency, (2)or 1-Handrails should be free of lead to an accessible area of refuge where sharp or abrasive elements people who are unable to use stairs may remain temporarily in safety to await assistance during 2-should have a circular an emergency evacuation cross section with an outside diameter of (32) minimum and (51) maximum; other shapes are allowable if they provide equivalent graspability and have a maximum cross-sectional dimension of (57). (38) minimum clearance between handrail and wall Ramps provide smooth transitions between the floor levels of a building. Ramps To have comfortable low slopes, they require relatively long runs. They are typically used to1- accommodate a change in level along an accessible route 2- or to provide access for wheeled equipment. Short, straight ramps act as beams and may be constructed as wood, steel, or concrete floor systems. Long or curvilinear ramps are usually of steel or reinforced concrete. STAIRS Types of stairs (shapes): 1- Straight-Run Stair 2- Quarter-Turn Stair Stair Terminology 4- Winding Stair 5- Circular Stair 6- Spiral Stair Types of stairs (MATERIALS): 1- Concrete stair A concrete stair is designed as an inclined, one-way reinforced slab with steps formed on its upper surface. If the stair is constructed after the floor beam or wall supports, it acts as a simple beam. If it is cast with the beam or slab supports, it is designed as a continuous beam. Concrete stairs require careful analysis of load, span, and support conditions; consult a structural engineer for final design requirements. (38) minimum @ concrete walls; (100) minimum@ masonry walls Stair slab thickness; rule of thumb: span/26 Span is equal to the horizontal distance between the slab supports  Concrete stair 1- 2- 3- STEEL STAIRS Steel stairs are similar in form to wood stairs. Steel channel sections serve as carriages and stringers. Stair treads span the distance between the stringers. Treads may consist of concrete-filled steel pans, or flat plates with a textured top surface. prefabricated steel stairs are available. Steel channel may rest on 1- a bearing plate on masonry, 2- or be hung on threaded rods from the floor structure above. areas. Elevators travel vertically to carry passengers, equipment, and freight from one level of a building to another. The two most common types are 1- electric elevators 2-and hydraulic elevators.. Electric elevators consist of a car that is mounted on guide rails, supported by hoisting cables, and driven by electric hoisting machinery in a penthouse. Geared traction elevators are capable of speeds up to (1.75 m/s) and are suitable for medium-rise buildings. Gearless traction elevators are available with speeds up to (6 m/s) and typically serve high-rise buildings. Top floor Hoisting cable is one of the wire cables or ropes used for raising and lowering an elevator car. Hoistway is the vertical enclosed space for the travel of one or more elevators. Traveling cable is one of the electric cables connecting an elevator car to a fixed electrical outlet in the hoistway. Sheaves Moving sidewalks are power-driven, continuously moving surfaces, similar to a conveyor belt, used for carrying pedestrians horizontally or along low inclines. https://www.youtube.com/watch?v=1jfNIBtfWDY