Sheet1ReferenceCalculationOutputDesign of Staircases:There were two staircases in the building to design. Design of mainstaircase is detailed here.Typical paln of the staircase is attached here with in figure 9-1.Choice of layout:Floor to floor height=3500mmNo. of rises=22Height of rise =350022=159mm60%Hence span/depth enhancement is possible.I.S.E. manualAssume span/depth ratio of 31 for continous oneway spanning staircase.Table3Span/depth=31*1.15=35.65Effective depth=4050/35.65=114mmAssume cover 25mm (mild exposure conditions and 2hr fire resistance)and using 12mm bars, choose h=150mm andWaist thicknessd=150-25-6=119mm=150mmHence waist thickness was selected as 150mm.Project: DahampayaFeatureDesign of staircaseDECDESIGN UNITDesignedDateEPC DIVISIONCheckedDateCENTRAL ENGINEERING CONSULTANCY BUREAU (CECB)Job CodeD-676Page01 of 13Loading:Consider 1m wide stripFactor for slope=(R2+G2)0.5/G=(1592+2502)0.5 /250=1.18Waist=(0.15).(24).(1.18).1=4.25kN/mSteps=(0.5).(0.159).(0.25).(24)=0.477kN/mTop finishes=(0.5).1=0.5kN/mSoffit plaster=(0.25).1.(1.18)=0.295kN/mTotal dead load=5.52kN/mImposed load=4.0kN/m2Design load=14.1kN/mDesign load=(1.4).(5.52)+(1.6).(4)=14.1kN/mFor landing area:Self weight of slab=(0.15).24=3.6kN/mSoffit plaster=(0.25).1.0=0.25kN/mTop finishes=0.5Top finishes=(0.5).1.0=0.5kN/mTotal dead load=4.35kN/mImposed load=4.0kN/m2Landing loadDesign load=(1.4).(4.35)+(1.6).(4)=12.5kN/m=12.5kN/mProject: DahampayaFeatureDesign of staircaseDECDESIGN UNITDesignedDateEPC DIVISIONCheckedDateCENTRAL ENGINEERING CONSULTANCY BUREAU (CECB)Job CodeD-676Page02 of 13Design for bendingSpecimen calculation for second flight:The staircase can be idealised as follows:W1=12.5kN/mW2=14.1kN/mRA=(12.5*0.9*0.45)+(14.1*2.5*2.15)+(12.5*0.65*3.725)4.05=27.4kNRB=(12.5*0.65*0.325)+(14.1*2.5*1.9)+(12.5*0.9*3.6)4.05=27.2kN0.65