Spread Footing Design

MINDANAO STATE UNIVERSITY- ILIGAN INSTITUTE OF TECHNOLOGY  (MSU-IIT) COLLEGE OF ENGINEERING ENGINEERING DEPARTMENT OF CIVIL ENGINEERING Name: Jhan Jkem B. Fontanilla Fontanilla Year&Course: BSCE -V legend : Input Value Subject: CE162 Computed Value Conclusion

ESIGN OF SPREAD FOOTIN Colu Column mn Shap Shape: e: Footing

:

Given

:

(cir (circl cle e / squa square re / rect rectan angl gle) e) squa square re Square (a) = 600 mm Square / Rectangle : rectangle (least dimension) B = 2.4 = 27.5 Mpa f'c = 414 MPa fy  qallowable = 285 kPa PDL

=

1580

PLL

= = = = =

1200 kN 30 mm 20 mm 23.6 KN/m^3 7 %

ΦbL ΦbS Unit weight of concrete assume footing weight %

kN

Dependable ultimate soil bearing: 435.91 435.91 kPa

=  Assume Footing weight, W f 

7 %Qu 4252 kN

= =

Required footing area: 10.437 m2

= For Rectangular footing: L = Af/B:

L use  Af(new)

= =

4.35 m 4.4 m

=

10.56 m2

=

412.05 kPa

net soil pressure

Footing depth as controlled by beam shear: = a

0.874 Mpa

= 600.0 mm In the longdirection d 677.85 mm mm

d

In the short directi 321.089 mm mm

Footing depth as controlled by punching shear: =

1.748

Mpa

Computed d  d 502.27 beam shear contols!

Check for bending

the long directio L'=(L - a) / 2 = 1.900 m Mu=q(L')^2 / 2 = 743.745 KN KN-m/m trial d = 680.00 mm

in the short direction L'=(B - a) / 2 = 0.900 m Mu=q(L')^2 / 2 = 166.879 KN KN-m/m trial d = 655 mm

Design a singly reinforced rectangular beam: b = 1000 mm

Ru

= = ρ = No. Of Rebars =

=

0.0032

=

0.0213

Long Direction 1.78716 0.004496 3057.148 11.0

ok! mm  /m 2

Check validity of the footing weight o 7% Total depth: h=d+100 = 780.00 mm mm Actual footing weight: Wf =1 .4BHh 272.14 KN   As Assumed umed foo footing ting weigh eight, t, Wf = % 297 97.6 .64 4 KN SHORT REBARS DISTRIBUTION : At central strip : = No. Of Rebars = At central strip : No. Of Rebars =

1 2 3 4 5 6

Short Direction Ru = 0.4322 p = 0.00105 As = pbd 2074.18 2074   .18 mm^2/m mm^2/m No. Of Rebars = 30.0

fairly close to actual no need eed to revis evise! e!

0.00 0 30

combination of Footing column footing square square square rectangle circle square circle rectangle rectangle sq square rectangle re rectangle P

dl 

P

LL

=

1580 1580 KN

=

1200 1200 KN

D

=

600

15 11 15

mmbar

mmbar -30

mmbar mmbar

 

680.00 mm

 

100.00 100.00 mm 0

-30

mm bar  

2.4 2.4 m  4.4  4.4 m

on