Isolated Footing Design Guide (EN 1992-1-1:2015) | Structural Engineering Reference | Eurocode 2

ISOLATED FOOTING DESIGN ES EN 1992-1-1:2015 j j j j j j




1Foundation Design (Isolated Footing) j j j j




An internal column transferring the loads given in table 1 is considered for isolated footing design. The
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material to be used for are C25/30 and S400. If the column size is 600mm by 600 mm. and the soil has
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presumptive bearing capacity of 280 Kpa(Allowable), determine the size and reinforcement j j j j j j j j j j j




necessary for the isolated footing to safely transfer the load. j j j j j j j j j j




ETABS OUTPUT j j




Fx j Fy j Fz j Mx j My j Mz j




Story Joint
Base 33Label Load Case/Combo
Comb1-Ultimate
j
j j
j
j j j
j




Base 33 Comb2-Service
j j j
-7.3925 -2.4641 3587.939 3.9611 -11.7307 -3.0603 j j j j j j




Table 1: Joint Reaction from ETABS to an internal column 1.1
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Material data j j




For C25/30 : 𝑓𝑐𝑘= 25 𝑀𝑝𝑎
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For S400: 𝑓𝑦𝑘= 400 𝑀𝑝𝑎
j j j j




Concrete design strength j j j



-5.1324 -1.8362 2564.1252 2.9776 -8.1731 -2.1384 j j j j j j




fcd = αccfck
j j j [ES EN 1992 −1 −1: 2015, Eqn. 3.15 ] j j j j j j j j




γc

Where: the recommended value of αcc is 0.85.
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fcd = 0.85 ∗25 1.5
j j j j j = 14.17 𝑀𝑝𝑎 j j




Steel design strength j j j




fyd = 𝑓𝑦𝑘j j j [ES EN 1992 −1 −1: 2015, Figure 3.8 ] j j j j j j j j




𝛾𝑠
fyd =400 1.115 = 347.83 Mpa
j j j jj j j




1.2 Footing proportioning j j




Factor of safety (F.S) j j j j




F . Ultimate load  358 .  11 .  .3 96  .1 399
j
j j j
j




S 7 . 939
2564 73  .8 173
125  .2 978
j




Service load j
j j j




all  280 Kpa
ult  .1 * 280 Kpa  391.81 Kpa j




399
Eccentricity at service load j j j j




Isolated footing j j Page |1 j j j j j j Af j

, ISOLATED FOOTING DESIGN ES EN 1992-1-1:2015 j j j j j j




e  M y  .8 173  
.3 x 3
j



j j
x
P 256 . 188 10 j




4 125
e  M x  .2 978  .1 x  3 j



y j j



P 2564 . 125 161 10 j




Now, the stress at the four corners of the footing can be determined from:
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  P 1(  6e x 6 e y )
A B B




Figure 1 Stress distribution on isolated footing with eccentric loading.
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Any plan dimension of footing, B and L, must satisfy two things:
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a)The maximum stress must be less than or equal to the allowable bearing
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capacity. j




b)The minimum stress must be greater than zero.
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Condition a) j j




Since the eccentricity is relatively equal in both axis’s, a square footing is ideal.
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 P 6 6e y
 1(  e x  )  all
j




max
A B B

2564.1252 6 * .3 x 3 6 * . 16 x 3 )  
1 
j j j




B2 188B 10 1 1B 10 all
(
2564.125 26 . x 3 )
  all
j j


1
2 B2 094
B 10
(


Isolated footing j j Page |2 j j j j j j Af j