Summary SheetSession Number :Date :Subject Expert :112.03.2007Dr. M.C. NatarajaDr. M.C. NatarajaProfessorDepartment of Civil Engineering,Sri Jayachamarajendra College of Engineering,Mysore – 570 006.Phone:0821-2343521, 9880447742E-mail: email@example.com
Learning Outcomes:• After this students will be able to do the detailing ofAfter this students will be able to do the detailing ofstaircases through drawing and bar bendingstaircases through drawing and bar bendingschedule.schedule.DETAILING OF STEEL INSTAIR CASES
Contents• Definition and parts of Stair cases• Types of stair cases• Requirements• Detailing principles• Problems• Art of Drawing• Bar bending scheduleDetailing of steel in Staircases
STAIR CASEDefinitionStair cases are used for the purpose ofgiving access to different floors of astructure.
Parts of stair a caseParts of stair a caseGTNRWθLeL1L2FLIGHTFIG.1 PARTS OF STAIR CASEFig. 2 DOG LEGGED STAIR CASE
Parts of stairsParts of stairsFlight and landing.StepsRise-RGoing-G=T-NTread-TNosing -NGTNRWθ
Types of stair casesTypes of stair casesBased on shape• Straight stairs• Dog legged stairs• Open well or open newel stairs• Geometrical stairs such as spiral, circular, etc.• Free standing stair cases
Open Well or Newel stair casesOpen Well or Newel stair casesI- FLIGHTII- FLIGHTIII- FLIGHTLANDINGWITH INTERMEDIATE FLIGHT WITHOUT INTERMEDIATE FLIGHTOPENWELL OPENWELL
OTHER STAIRCASESOTHER STAIRCASESSPIRAL ANDGEOMETRICSTAIRCASESRISER AND TREAD STAIRCASE
Based on type of spanBased on type of span• Horizontally spanning or transverselyspanning SC• Longitudinally spanning SC.For details refer IS:456-2000 and SP-34.CLASSIFICATION
Guide lines for fixing the dimensionsGuide lines for fixing the dimensionsRise (R) : 150mm to 180mmTread (T) : 220 mm to 250 mm- for residential buildings.Rise (R) : 120 to 150 mmTread (T) : 250 mm to 300 mm – for public buildings[T + 2R] : Between 500 mm to 650 mmThe width of the stair• 0.8 m to 1 m for residential building and• 1.8 m to 2 m for public building.
Guide lines for fixing the dimensionsGuide lines for fixing the dimensions Contd…Contd…• The width of the landing is equal to the width of stairs.• The number of steps in each flight should not be greaterthan 12• The pitch of the stair should not be more than 38 degrees.• The head room measured vertically above any step orbelow the mid landing shall not be less than 2.1 m.
Design of stairsDesign of stairsDesign for maximum bending moment and check formaximum shear force.The depth is to be fixed from deflection criteria.Stair case slab is designed as a conventional slab.All rules regarding the detailing are similar to that of slab.Enough development and anchorage lengths for steelshould be provided.
Transversally spanning stair caseTransversally spanning stair caseSTEPSSTRINGERBEAMS STRINGERBEAM0.5 Ast0.1Le-0.15LeLeAstD1D2STIRRUPMAIN STEELDIST. STEELRefer SP-34 for more details
MAIN Ast0.5AstDSDBbWL6φmLe0.1-0.15LeφmDSSTAIR CASE SUPPORTED ON SIDEBEAMS-DETAILSSTIRRUP DETAILS ANDHOOKTRANSVERSLY SPANNING
LeLANDINGWAIST SLABCase (a)EFFECTIVE SPAN FORLONGITUDINALLYSPANNING STAIRCASESWALLWAIST SLAB SUPPORTED AT THEENDS OF LANDINGS
EFFECTIVE SPAN FORLONGITUDINALLYSPANNING STAIRCASESX X Y YLeCase (c)Case (b)LeLe=G +[ X +Y], X ≤1m AND Y ≤1mLe=c/c of beamsGOING=G
Longitudinally spanning SCLongitudinally spanning SCDetailingDetailing• Steel at bottom longitudinally-tension• Anchorage and development steel• Distribution steel• Row of chairs• Nominal foundation for ground flight
ExerciseExerciseA dog legged stair case is to be detailed with thefollowing particulars:Clear dimension of stair case room=4.48 m x 2.1 mThe floor to floor height is 3.2 mWidth of each tread =250 mmWidth of each rise = 160 mmThickness of waist slab = 150 mmWidth of flight =1mAll round wall = 230 mm
ExerciseExercise contd.,contd.,Both flights are supported at the ends oflanding on 230 mm wall.(Landing and flight spans in the same direction)The first flight starts from the plinth levelMain steel for each flight = #12@120Distribution steel for each flight = #8@ 200Use M20 concrete and Fe 415 steel.Draw to a suitable scaleThe plan of stair caseSectional elevation of the Ground flightSectional elevation of the First flightBar bending schedule
SolutionSolutionDimensioning:R=160 mm, T= 250 mmFloor to floor height = 3200mmNo of rises = 3200/R = 20. Each flight has 10 rises.No of treads per flight=10-1 =9Width of landing along flight= (4480-9x250)/2 = 1115mm.Going of flight=9x250 =2250mmDevelopment length = 47φ= 47 x 12 = 564 mm
ExerciseExercisePlan of stair casePLAN1115 mm 1115 mm2250 mmLe = 4710 mmGap=0.1m 2100Clear dimension of stair case room=4.48 m x 2.1 m
ROW OF CHAIRS500 mm500 mmGLWallFOUNDATIONGROUND FLIGHTMAIN STEEL# 12 @ 120DIST. STEEL# 8 @ 200150Ld =564REINFORCEMENTFROM BMLd =564FLOOR LEVELLANDING FIRST FLIGHTR=160T= 250LAP LDETAILINGLanding and flight spans longitudinally[A][C][D,E]-AnchoragesteelMain steel [B]
Y=0.3 l or LdLANDINGBEAM500500GLFOOTINGGROUND FLIGHTFIRST FLIGHTMAIN STEEL # 12 @ 120DIST. STEEL# 8 @ 150LANDINGBEAM150XlYY150INTERMEDIATELANDINGROW OFCHAIRSX = 0.15 l or LdMAIN STEELDS150PLANLeDETAILINGFlight spans longitudinally on landing beams
LdLdTExtra steel ifneededConcrete spallingdue to tension insteelWrongokDetails at the junction of flight and landingDetails at the junction of flight and landing
STRAIGHT STAIR CASESTRAIGHT STAIR CASERefer SP-34 and learn the details
Member MarkNo. ofbarsDia.inmmLengthinm/pieceTotallengthin mBar details Remarks#12 #8SCGFlA 9 12 measure X18spacings,main barB 9 12 measure X2 Main barC Count 8 960 Y1Dist. BarL=1000-2ECBar bending scheduleFor exercise problem
Stair-GroundFloorD 9 12 measure X3AnchoragebarsE 9 12 measure X4AnchoragebarsTotal length in m/diameter - -Calculations are based onactual measurement ondrawing sheet.Weight in kg/m -- --Total weight in kg/diameter --- ---Bar bending schedule-Contd.,
Estimation of quantity of concreteVolume of concrete = L x B x DL= length along the central line in m-measuredB=Breadth in mD=Thickness of slab in mPlus concrete in footingWeight of concrete, kg = Volume x density
ConclusionStudents have learnt the following:• Types of staircases.• Effective span concept.• Requirements of staircase.• Detailing of steel.• Importance of development length and anchorages.• Drawing to scale and bar bending schedule.