The following picture is about stairs in a house with 14 stairs with a height of 250 cm. What is the height of each footing from 14 steps?
Answers
Answered by
2
Answer: the height of each footing is 17 6/7 cm.
Step-by-step explanation:
There are stairs with 14 stairs with a height of 250 cm. The height of each footing from 14 footings is 17 6/7 cm.
DISCUSSION:
To find the height of each footing, we must divide the high number of all known steps with a lot of footing.
Known :
• 14 stairs
• Total height = 250 cm
Was asked
Height of each footing.
Settlement:
14 steps x Height of each footing = 250 cm
// we move 14 to the right hand side, the symbol changes to the opposite of times, which is for //
High every footing = 250 cm / 14 footing
Height of each footing = (238 + 12) cm / 14 footing
Height of each footing = 17 12/14 cm
Height of each footing = 17 6/7 cm
So, the height of each footing is 17 6/7 cm.
Answered by
1
It is a dog-legged staircase
Floor to floor height =3.2m=3.2m
Height/flight =(3.2/2)=1.6m=(3.2/2)=1.6m
Assume Riser =160mm=160mm
Tread =250mm=250mm
No. of riser in one flight =(1600/160)=10=(1600/160)=10Nos.
No. of tread in one flight =R−1=10−1=9=R−1=10−1=9

Trial depth=eff.spanS/D ratio×M.F.S/Dratio=20,M.F.=1.4dreqd=505020×1.4=180.35=eff.spanS/D ratio×M.F.S/Dratio=20,M.F.=1.4dreqd=505020×1.4=180.35
Assume D = 250 mm
d= D-clear cover −ɸ/2=250−25−20/2d=215mm.−ɸ/2=250−25−20/2d=215mm.
Load calculation on step portion
a) D.L. of waist slab =D×25×R2+T2−−−−−−−√T=0.3×25×1602+2502−−−−−−−−−√250=8.9kN/m2=D×25×R2+T2T=0.3×25×1602+2502250=8.9kN/m2
b) D.L. of step =R/2×25=0.16/2×25=1.875kN/m2=R/2×25=0.16/2×25=1.875kN/m2
c) F.F.=1.25kN/m2F.F.=1.25kN/m2
d) L.L.=3kN/m2L.L.=3kN/m2
Total =8.9+1.875+1.25+3=15.025kN/m2=8.9+1.875+1.25+3=15.025kN/m2
Factored Load =1.5×15.025=22.53kN/m2=1.5×15.025=22.53kN/m2
Load calculation on landing portion:
a) D.L. of slab =D×25=0.25×25=6.25kN/m2.=D×25=0.25×25=6.25kN/m2.
b) F.F.=1.25kN/m2F.F.=1.25kN/m2
c) L.L.=3kN/m2L.L.=3kN/m2
Total =6.25+1.25+3=10.5kN/m2=6.25+1.25+3=10.5kN/m2
Factored Load =10.5×1.5=15.75kN/m2=10.5×1.5=15.75kN/m2
First Flight:

Calculations:
∑M@C=0VA×3.525−47.87×(1.06+1.4)−22.05×(0.7)=0VA=37.78kN∑Fy=0VA+VC=47.87+22.05VC=32.14kNB.MMAX=37.78×1.67−22.53×1.6722=31.67kNmB.M>@B=32.14×1.4−22.05×0.7=29.56kNm.∑M@C=0VA×3.525−47.87×(1.06+1.4)−22.05×(0.7)=0VA=37.78kN∑Fy=0VA+VC=47.87+22.05VC=32.14kNB.MMAX=37.78×1.67−22.53×1.6722=31.67kNmB.M>@B=32.14×1.4−22.05×0.7=29.56kNm.
Floor to floor height =3.2m=3.2m
Height/flight =(3.2/2)=1.6m=(3.2/2)=1.6m
Assume Riser =160mm=160mm
Tread =250mm=250mm
No. of riser in one flight =(1600/160)=10=(1600/160)=10Nos.
No. of tread in one flight =R−1=10−1=9=R−1=10−1=9

Trial depth=eff.spanS/D ratio×M.F.S/Dratio=20,M.F.=1.4dreqd=505020×1.4=180.35=eff.spanS/D ratio×M.F.S/Dratio=20,M.F.=1.4dreqd=505020×1.4=180.35
Assume D = 250 mm
d= D-clear cover −ɸ/2=250−25−20/2d=215mm.−ɸ/2=250−25−20/2d=215mm.
Load calculation on step portion
a) D.L. of waist slab =D×25×R2+T2−−−−−−−√T=0.3×25×1602+2502−−−−−−−−−√250=8.9kN/m2=D×25×R2+T2T=0.3×25×1602+2502250=8.9kN/m2
b) D.L. of step =R/2×25=0.16/2×25=1.875kN/m2=R/2×25=0.16/2×25=1.875kN/m2
c) F.F.=1.25kN/m2F.F.=1.25kN/m2
d) L.L.=3kN/m2L.L.=3kN/m2
Total =8.9+1.875+1.25+3=15.025kN/m2=8.9+1.875+1.25+3=15.025kN/m2
Factored Load =1.5×15.025=22.53kN/m2=1.5×15.025=22.53kN/m2
Load calculation on landing portion:
a) D.L. of slab =D×25=0.25×25=6.25kN/m2.=D×25=0.25×25=6.25kN/m2.
b) F.F.=1.25kN/m2F.F.=1.25kN/m2
c) L.L.=3kN/m2L.L.=3kN/m2
Total =6.25+1.25+3=10.5kN/m2=6.25+1.25+3=10.5kN/m2
Factored Load =10.5×1.5=15.75kN/m2=10.5×1.5=15.75kN/m2
First Flight:

Calculations:
∑M@C=0VA×3.525−47.87×(1.06+1.4)−22.05×(0.7)=0VA=37.78kN∑Fy=0VA+VC=47.87+22.05VC=32.14kNB.MMAX=37.78×1.67−22.53×1.6722=31.67kNmB.M>@B=32.14×1.4−22.05×0.7=29.56kNm.∑M@C=0VA×3.525−47.87×(1.06+1.4)−22.05×(0.7)=0VA=37.78kN∑Fy=0VA+VC=47.87+22.05VC=32.14kNB.MMAX=37.78×1.67−22.53×1.6722=31.67kNmB.M>@B=32.14×1.4−22.05×0.7=29.56kNm.
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