DESIGN OF STAIR CASE

DESIGN OF  STAIR CASE

Vertical distance between two floors= 3.2 m

Assuming two flights

Height  Of each  flights= 3.2/2 = 1.6m

Clear Width Of each Step=1500mm

Rise  Of  each Step =150mm

Thread Of each Step=230mm

No  of  rise/flight=12

Going of each flight=12×230 = 2760mm

Width of Support=230mm

Grade of Concrete=M₂₀

Grade of Steel =Fe₄₁₅

SPAN OF STAIR CASE:

Clear Span=6m

Effective Span=6000+230 =6230mm

                        

DESIGN OF FLIGHT:

Bearing of the flight  = 150mm

Effective horizontal Span=6.075m

THICKNESS OF SLAB:

Considering 50mm Per m of Span

1.6×50=300mm

2.Dead load=230×25×1×1 = 5750N/m²

3.Finish=50×24=1200 N/m² = 6950N/m²           

Corresponding load/eq.moment  of span

(R²+T²)/T)×L

Load/M                       =8297.41N/M

Waist slab&ceiling finish =8.300N/M

Dead load of slab                    =1/2×230×150×19=0.32KN/M

Live Load                               =4KN/M

Total Load                              =12.62KN/M

Factored Load                        =12.62×1.5=18.93KN/M

Factored load for 1.5M           =18.93×1.6=30.288KN/M

MOMENT AND REACTION:

RA=50.19KN & RB=50.30KN

Moment @3.0M

50.3×3.0-(8.5×0.5×0.32)+(12.52×1×1.10)+(30.26×0.720)

M  =95.68KNM

Mu=M_u  limit

95.68⁶  =0.138×20×1000×d²

d  =186.18mm<200mm

TO GET AST:

Ast         = 50×(1-1√1-(4.6/20)×(95.68×10⁶/1000×200²))/(415/20))

              =1.12%

Ast         =1.12/100×1000×200 = 2240mm

No .of 16mm dia bars = 2240/(3.14(16)²/4) = 11 bars

DISTRIBUTION BARS

(0.12/100)×1000×200 =240mm²

Spacing of 6mm dia bars =(3.14(6)²/4)240×1000=120mmc/c

Provide 6 mm dia @ 120mmc/c as distribution steel

DESIGN OF LANDING:

Reaction from flight = R_b×1.5-(8,5×0.5)×0.5+(12.52×1) ×0.5

                                   =68KNM

M_{u  =}  M_u limit

68×10⁶ = 0.138×20×1000×d²

d  =  157 < 200mm

Ast  =  50×(1-1√1-(4.6/20)×(68×10⁶/1000×200²))/(415/20))

        =0.8%

Ast =0.8/100×1000×200=1600mm²

Spacing of 12 mm dia bars =(3.14(12)²/4)1600×1000= 70mm

Provide 12 mm dia @ 70mmc/c   on  landing

About Author:

I am Thomas Britto here to share my experiences in the civil engineering field to all my readers.Today many students are struggling to buy books at high prices. So I decided to start a blog and share my experience and knowledge with all my readers.

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