Problem425 pts Proposed design fc 25 MPa Pr 2000 kN M400 kNm

Problem4(25 pts) Proposed design: f,c= 25 MPa Pr= 2000 kN M400 kN/m , 400 MPa 450 mmx 450 mm section 8 # 25 bars, 4 in each face parallel to the axis of bending » 3500 m l . · #10 ties @ every 450 mm L.J 20 mm clear cover to the stirrup Pr=2000 kN The reinforced concrete column shown above is located in the middle of a 2 bay- 3 storey frame at the first floor level with interior exposure. During the design it was noted that the load combination (MrPr) on the interaction diagram from the Handbook was somewhere in between f,/fy- 0.5 and f,/fy-1.0 radial lines. a-) Check the slenderness of this column.

Solution

a-) check for slenderness

l/b = 3500/450 = 7.78

so this is a shoet column

b-) these chrcks are performed in column

1:- ECCENTRICITY :- Eccentricity should be less then 0.05 X b that is 0.05 X 450 = 22.5

its L/500+B/30 = 3500/500 + 450/30 = 7+15 = 22

so its less then 22.5 hense safe

2:- AREA OF REINFORCEMENT :- ITS must between 0.8 to 6 % of concrete area

here 8 bars of 25 mm dia

area of reinforcement = pai/4 D² = 3925 mm²

area of concrete = 450 x 450 = 202500 mm²

reinforcement % = 1.9% hence safe

3:- spacing :- spacing should be equals or more of least lateral dimention that is 450 mm

here spacing is 450 mm hence safe