Thanks a lot for your reply and for the attached document, interesting.
For the preliminary calculation for allowable tension stress ( using 4 *SQRT* fc ) is 1.8 mPa, this 1.8 should be compared to what to check if okay or not?
Also for Check lateral stability, what check need to do??
Base on ACI code, If I did a precast one beam 60 cm x 60 cm x 1200 cm.
the compressive strength used during design is design be 50 mpa. if I use hardener during precast, and I got 30 mpa compressive strength after 24 hours.
Can I lift the beam up if the strength of concrete reach 30 mpa after...
Thanks for the reply,
I am aware about this, what I am looking a clear sentence telling the f'c used during design is the compressive strength on cylinder.
is it mentioned anywhere in the ACI code?
in ACI code, in calculation, we used f'c as the compressive strength on cylinders after 28 days.
Where this covered in the ACI code.
Which part telling the the compressive strength is related to Cylinder.
Thanks Lexpatrie, the reason why I am asking is that in the example which you provided above, we should use 0.85 x ∅ x f'c x A1 x sqrt(A2 / A1)2 instead of ∅ x 0.85 x f'c A1.
but in one of the example which I saw, The allowable bearing on the base of the column used was ∅ x 0.85 x f'c A1
Thanks for the reply.
I am not able to identify when to use the value of ∅ x 0.85 x f'c A1 and when to use 0.85 x ∅ x f'c x A1 x sqrt(A2 / A1)2.
What does mean "When the contact-supporting surface on the footing is wider on all sides than the loaded area"
The maximum bearing load on the bottom of the column (ACI Code Table 22.8.3.2) = ∅ x 0.85 x f'c A1.where A1 is the area of the contact surface between the column and the footing.
When the contact-supporting surface on the footing is wider on all sides than the loaded area, the maximum bearing...
@Celt83, you really help me in this regards and make things much clear.
Last thing is that you assumed that 𝛅c = 1", which calculation required to get this value?
Thanks Celt83 and BAretired for being very supportive and very helpful, your post is very clear and thanks too for the guys which support me in this thread.
However, I was trying to get the deflection thinking in such way I would get the deformation of foundation.
You both already have me hint...
@BAretired thanks a lot, yes with Macaulay's method I can solve the 2 unknown constants, but I need to consider that the displacement below the 2 columns are zeros.
Is it correct to consider the deflection underneath the two columns are zero?
Thanks a lot Celt83 for all your replies, lets consider it first as one uni-axial moment.
by using EI dy4/dx4 + ky = q, I will get 6 unknown values to be identified.
to solve them, I need to have 6 equations. is that correct?
I need to get the deflection function D(x)
from M(x), I get the deflection function D(x) by doing ∬ M(x)
In the deflection functions D(x), I got 6 unknowns values (Const1, Const2, Const3, Const4, Const4, Const6) and I need to know those values
to solve those 6 unknowns values, I need 6...
Thanks Celt83, yes I am dealing with Biaxial bending moment.
I already have the Shear and bending moment diagram V(x) and M(x).
If I consider the 2 columns as pins I think I can solve the remaining 4 equations, but can I consider the columns as pins? cause for sure there will be settlement over...
Thanks gentlemen for your reply,
I changed the constants as you were right, it was confusing using the same numbers.
I got the pressure by using P / A + P * Ye / Ix * y + P * Xe / Iy * x and then using the Chart Ten to calculate K in case there is tension beneath the foundation.
The way I did...
I am trying to get the deflection D(x) under a combined foundation.
I manage to get the function bending moment M(x) by dividing the area in 3 places.
- Equation 1: from Edge of foundation to First Column C1
- Equation 2: From Column C1 to Column C2
- Equation 3: From Column C2 to the edge...