In order to calculate the provided reinforcement the user has to select the element that will be calculated and access the RC Foundation Design command from the Design menu/Provided reinforcement for RC elements.
In the case of the foundations the program will provide additional calculation regarding ground under foundation: tensions, settlement, etc.
The first window that will appear will allow us to select the load cases that will be used for calculating the reinforcement.
The display has changed and on screen we have some new windows where we can see the geometry of the element.
In this window the user will provide the starting point of the
dimensioning process by indicating the dimensions of the foundation. Some of these dimensions can be fixed so that the program will not change them during calculation.
Before calculating the provided reinforcement we have to adjust four sets of calculation parameters:
- RC Element/Soil
- Analysis menu/Geotechnical options...
- Analysis menu/Calculation options...
- Analysis menu/Reinforcement pattern...
In the first set mentioned, Soil, the user will provide information regarding the soil under the foundation: layers, levels of the foundation relative to zero level, admissible stress for ground and water level.
The second set named Geotechnical options allows the user to choose what kind of verification to perform: settlement, rotation, sliding, allowable eccentricity.
The calculation option set contain four tabs:
- General - Concrete
- Longitudinal reinforcement - Transversal reinforcement
In the windows below we can see the parameters for our example:
After the personalization of the calculation options we can save these sets in order to reuse them in other projects. We can do this by pressing the Save As... button.
The final set of options to be adjusted is the Reinforcement pattern.
Because the program will propose a real solution for reinforcement, we will have to provide some rules that the program will follow when it will draw the reinforcement.
Here are the parameters for reinforcement patterns used for calculating the provided reinforcement.
Same as before, the user can save the reinforcement pattern options for later use with other projects by pressing the Save as button.
Next step is to indicate the options sets to be used for calculation.
For this select the Options set... from the Analysis menu.
For calculation the reinforcement select the Calculation command from the Analysis menu and press the Calculate button in the window that just opened.
When the calculation is finished we can switch to the Foundation-Results tab and see the graphic results.
In the next tab, Foundation-Reinforcement, we can see the reinforcement bars provided by the program. We can even change the reinforcement and recalculate the element.
In the last tab called Foundation-note we can see a full calculation note for the current calculated element. This calculation note can also be generated by selecting the Calculation note command from the Results menu. This calculation note can be save as a *.rtf file and can be attached to the project documentation.
Here it is the calculation note provided for our foundation:
1 Spread footing: Foundation3 Number: 1
1.1 Basic data
1.1.1 Assumptions
Geotechnic calculations according to : EN 1997-1:2008
Concrete calculations according to : EN 1992-1-1:2004 AC:2008
Shape selection : without limits
1.1.2 Geometry:
A = 1,90 (m) a = 0,60 (m)
Cover deviations: Cdev = 1,0(cm), Cdur = 0,0(cm) 1.1.3 Materials
Concrete : C20/25; Characteristic strength = 20,00 MPa Unit weight = 2501,36 (kG/m3)
Bi-linear stress distribution [3.1.7(2)]
Longitudinal reinforcement : type B500C Characteristic strength
= 500,00 MPa
Ductility class: C
Horizontal branch of the stress-strain diagram
Transversal reinforcement : type B500C Characteristic strength
= 500,00 MPa 1.1.4 Loads:
Foundation loads:
Case Nature Group N Fx Fy Mx My
(kN) (kN) (kN) (kN*m) (kN*m)
DL1 dead load 3 505,05 -0,20 6,16 -7,05 -0,32
DL2 dead load 3 110,64 -0,04 2,12 -2,44 -0,07
DL3 dead load 3 177,63 -0,07 4,18 -4,83 -0,11
LL1 live load 3 132,97 -0,05 2,81 -3,23 -0,08
SN1 snow 3 23,28 -0,00 0,03 -0,02 -0,01
SEI_X7 seismic 3 -24,76 6,26 0,62 -1,55 11,62
SEI_Y8 seismic 3 40,26 -0,73 2,61 -6,14 -1,19
SEI_Z8 seismic 3 -83,67 0,26 -1,53 1,82 0,30
SPE_NEW10 seismic 3 -37,78 6,12 0,95 -2,85 11,35
SPE_NEW11 seismic 3 -61,94 6,55 -0,62 0,84 12,07
SPE_NEW12 seismic 3 -11,74 6,40 0,30 -0,25 11,89
SPE_NEW13 seismic 3 12,42 5,96 1,86 -3,94 11,17
SPE_NEW14 seismic 3 7,73 1,22 2,34 -6,06 2,38
SPE_NEW15 seismic 3 -72,79 2,68 -2,88 6,22 4,77
SPE_NEW16 seismic 3 -22,59 2,53 -1,96 5,13 4,59
SPE_NEW17 seismic 3 57,94 1,07 3,25 -7,15 2,20
SPE_NEW18 seismic 3 -79,02 1,91 -0,56 -0,49 3,43
SPE_NEW19 seismic 3 -103,18 2,35 -2,12 3,20 4,14
SPE_NEW20 seismic 3 64,16 1,84 0,93 -0,44 3,55
SPE_NEW21 seismic 3 88,32 1,40 2,50 -4,13 2,83
Backfill loads:
Case Nature Q1
(kN/m2)
1.1.5 Combination list
1/ ULS A1 : 1.35DL1+1.35DL2+1.35DL3+1.50LL1+0.75SN1 2/ ULS A1 : 1.35DL1+1.35DL2+1.35DL3+1.50LL1
3/ ULS A1 : 1.35DL1+1.35DL2+1.35DL3
4/ ULS A1 : 1.00DL1+1.00DL2+1.00DL3+1.50LL1+0.75SN1 5/ ULS A1 : 1.00DL1+1.00DL2+1.00DL3+1.50LL1
6/ ULS A1 : 1.00DL1+1.00DL2+1.00DL3
7/ ULS A1 : 1.35DL1+1.35DL2+1.35DL3+1.05LL1+1.50SN1 8/ ULS A1 : 1.35DL1+1.35DL2+1.35DL3+1.50SN1
9/ ULS A1 : 1.00DL1+1.00DL2+1.00DL3+1.05LL1+1.50SN1 10/ ULS A1 : 1.00DL1+1.00DL2+1.00DL3+1.50SN1
11/ ULS A2 : 1.00DL1+1.00DL2+1.00DL3+1.30LL1+0.91SN1 12/ ULS A2 : 1.00DL1+1.00DL2+1.00DL3+1.30LL1
13/ ULS A2 : 1.00DL1+1.00DL2+1.00DL3
14/ ULS A2 : 1.00DL1+1.00DL2+1.00DL3+0.91LL1+1.30SN1 15/ ULS A2 : 1.00DL1+1.00DL2+1.00DL3+1.30SN1
16/ SLS : 1.00DL1+1.00DL2+1.00DL3+1.00LL1 17/ SLS : 1.00DL1+1.00DL2+1.00DL3
18/ SLS : 1.00DL1+1.00DL2+1.00DL3+1.00SN1
19/ SLS : 1.00DL1+1.00DL2+1.00DL3+1.00LL1+1.00SN1 20/* ULS : 1.35DL1+1.35DL2+1.35DL3+1.50LL1+0.75SN1 21/* ULS : 1.35DL1+1.35DL2+1.35DL3+1.50LL1
22/* ULS : 1.35DL1+1.35DL2+1.35DL3
23/* ULS : 1.00DL1+1.00DL2+1.00DL3+1.50LL1+0.75SN1 24/* ULS : 1.00DL1+1.00DL2+1.00DL3+1.50LL1
25/* ULS : 1.00DL1+1.00DL2+1.00DL3
26/* ULS : 1.35DL1+1.35DL2+1.35DL3+1.05LL1+1.50SN1 27/* ULS : 1.35DL1+1.35DL2+1.35DL3+1.50SN1 28/* ULS : 1.00DL1+1.00DL2+1.00DL3+1.05LL1+1.50SN1 29/* ULS : 1.00DL1+1.00DL2+1.00DL3+1.50SN1 30/* SLS : 1.00DL1+1.00DL2+1.00DL3+1.00LL1+0.50SN1 31/* SLS : 1.00DL1+1.00DL2+1.00DL3+1.00LL1
32/* SLS : 1.00DL1+1.00DL2+1.00DL3
33/* SLS : 1.00DL1+1.00DL2+1.00DL3+0.70LL1+1.00SN1 34/* SLS : 1.00DL1+1.00DL2+1.00DL3+1.00SN1
35/* SLS : 1.00DL1+1.00DL2+1.00DL3+0.50LL1
36/* SLS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1+0.20SN1 37/* SLS : 1.00DL1+1.00DL2+1.00DL3+0.20SN1
38/* SLS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1
39/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1+1.00SEI_X7 40/* ALS : 1.00DL1+1.00DL2+1.00DL3+1.00SEI_X7 41/* ALS : 1.00DL1+1.00DL2+1.00DL3
42/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1+1.00SEI_Y8 43/* ALS : 1.00DL1+1.00DL2+1.00DL3+1.00SEI_Y8 44/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1+1.00SEI_Z8 45/* ALS : 1.00DL1+1.00DL2+1.00DL3+1.00SEI_Z8
46/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1+1.00SPE_NEW10 47/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1+1.00SPE_NEW11 48/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1+1.00SPE_NEW12 49/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1+1.00SPE_NEW13 50/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1+1.00SPE_NEW14 51/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1+1.00SPE_NEW15 52/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1+1.00SPE_NEW16 53/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1+1.00SPE_NEW17 54/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1+1.00SPE_NEW18 55/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1+1.00SPE_NEW19 56/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1+1.00SPE_NEW20 57/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1+1.00SPE_NEW21 58/* ALS : 1.00DL1+1.00DL2+1.00DL3+1.00SPE_NEW10
59/* ALS : 1.00DL1+1.00DL2+1.00DL3+1.00SPE_NEW11 60/* ALS : 1.00DL1+1.00DL2+1.00DL3+1.00SPE_NEW12 61/* ALS : 1.00DL1+1.00DL2+1.00DL3+1.00SPE_NEW13 62/* ALS : 1.00DL1+1.00DL2+1.00DL3+1.00SPE_NEW14 63/* ALS : 1.00DL1+1.00DL2+1.00DL3+1.00SPE_NEW15 64/* ALS : 1.00DL1+1.00DL2+1.00DL3+1.00SPE_NEW16 65/* ALS : 1.00DL1+1.00DL2+1.00DL3+1.00SPE_NEW17 66/* ALS : 1.00DL1+1.00DL2+1.00DL3+1.00SPE_NEW18 67/* ALS : 1.00DL1+1.00DL2+1.00DL3+1.00SPE_NEW19 68/* ALS : 1.00DL1+1.00DL2+1.00DL3+1.00SPE_NEW20 69/* ALS : 1.00DL1+1.00DL2+1.00DL3+1.00SPE_NEW21 70/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1-1.00SEI_X7 71/* ALS : 1.00DL1+1.00DL2+1.00DL3-1.00SEI_X7 72/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1-1.00SEI_Y8 73/* ALS : 1.00DL1+1.00DL2+1.00DL3-1.00SEI_Y8 74/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1-1.00SEI_Z8 75/* ALS : 1.00DL1+1.00DL2+1.00DL3-1.00SEI_Z8
76/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1-1.00SPE_NEW10 77/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1-1.00SPE_NEW11 78/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1-1.00SPE_NEW12 79/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1-1.00SPE_NEW13 80/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1-1.00SPE_NEW14 81/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1-1.00SPE_NEW15 82/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1-1.00SPE_NEW16 83/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1-1.00SPE_NEW17 84/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1-1.00SPE_NEW18 85/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1-1.00SPE_NEW19 86/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1-1.00SPE_NEW20 87/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1-1.00SPE_NEW21 88/* ALS : 1.00DL1+1.00DL2+1.00DL3-1.00SPE_NEW10
89/* ALS : 1.00DL1+1.00DL2+1.00DL3-1.00SPE_NEW11 90/* ALS : 1.00DL1+1.00DL2+1.00DL3-1.00SPE_NEW12 91/* ALS : 1.00DL1+1.00DL2+1.00DL3-1.00SPE_NEW13 92/* ALS : 1.00DL1+1.00DL2+1.00DL3-1.00SPE_NEW14 93/* ALS : 1.00DL1+1.00DL2+1.00DL3-1.00SPE_NEW15 94/* ALS : 1.00DL1+1.00DL2+1.00DL3-1.00SPE_NEW16 95/* ALS : 1.00DL1+1.00DL2+1.00DL3-1.00SPE_NEW17 96/* ALS : 1.00DL1+1.00DL2+1.00DL3-1.00SPE_NEW18 97/* ALS : 1.00DL1+1.00DL2+1.00DL3-1.00SPE_NEW19 98/* ALS : 1.00DL1+1.00DL2+1.00DL3-1.00SPE_NEW20 99/* ALS : 1.00DL1+1.00DL2+1.00DL3-1.00SPE_NEW21 100/* ALS : 1.00DL1+1.00DL2+1.00DL3+0.30LL1
1.2 Geotechnical design
1.2.1 Assumptions
Cohesion reduction coefficient: 0,00
Smooth precast foundation 6.5.3(10)
Sliding with soil pressure considered: for X and Y directions
Design approach: 1 A1 + M1 + R1
' = 1,25
Minimum reference level: Nf = -0,50 (m) Clay
• Soil level: 0.00 (m)
• Unit weight:2243.38 (kG/m3)
• Unit weight of solid: 2753.23 (kG/m3)
• Internal friction angle: 25.0 (Deg)
• Cohesion: 0.06 (MPa)
1.2.3 Limit states
Stress calculations
Soil type under foundation: not layered Design combination ULS A1 : 1.35DL1+1.35DL2+1.35DL3+1.50LL1+0.75SN1
Load factors: 1.35 * Foundation weight 1.35 * Soil weight Calculation results: On the foundation level
Weight of foundation and soil over it: Gr = 112,89 (kN) Design load:
Foundation depth: Dmin = 1,00 (m)
Allowable stress calculation method: Semi-empirical - stress limit qu = 0.50 (MPa)
ple* = 0,48 (MPa) De = Dmin - d = 1,00 (m) kp = 0,91
q'0 = 0,02 (MPa)
qu = kp * (ple*) + q'0 = 0,45 (MPa)
Stress in soil: qref = 0.43 (MPa) Safety factor: qlim / qref = 1.061 > 1
Uplift
Uplift in ULS
Design combination ULS A1 : 1.35DL1+1.35DL2+1.35DL3+1.50LL1
Load factors: 1.00 * Foundation weight 1.00 * Soil weight
Contact area: s = 0,02
slim = 0,33 Sliding
Design combination ULS A1 : 1.35DL1+1.35DL2+1.35DL3+1.50LL1
Load factors: 1.00 * Foundation weight 1.00 * Soil weight Weight of foundation and soil over it: Gr = 83,62 (kN) Design load:
Nr = 1354,06 (kN) Mx = -45,21 (kN*m) My = -1,29 (kN*m) Equivalent foundation dimensions: A_ = 1,90 (m)B_ = 1,90 (m)
Sliding area: 3,61 (m2)
Foundation/soil friction coefficient: tan(d = 0,30
Cohesion: cu = 0.06 (MPa) Value of force preventing foundation sliding:
- On the foundation level: Rd = 405,38 (kN) Stabilility for sliding: 55.73 > 1 Average settlement
Soil type under foundation: not layered Design combination SLS : 1.00DL1+1.00DL2+1.00DL3+1.00LL1+1.00SN1
Load factors: 1.00 * Foundation weight 1.00 * Soil weight Weight of foundation and soil over it: Gr = 83,62 (kN) Average stress caused by design load: q = 0,29 (MPa) Thickness of the actively settling soil: z = 4,75 (m) Stress on the level z:
- Additional: zd = 0,02 (MPa)
- Caused by soil weight: z = 0,13 (MPa) Settlement:
- Original s' = 0,5 (cm)
- Secondary s'' = 0,0 (cm)
- TOTAL S = 0,5 (cm) < Sadm = 5,0 (cm)
Safety factor: 10.25 > 1 Settlement difference
Design combination SLS : 1.00DL1+1.00DL2+1.00DL3+1.00LL1+1.00SN1
Load factors: 1.00 * Foundation weight 1.00 * Soil weight
Settlement difference: S = 0,0 (cm) < Sadm = 5,0 (cm) Safety factor: 1626 > 1
Rotation
About OX axis
Design combination ULS A1 : 1.35DL1+1.35DL2+1.35DL3+1.50LL1
Load factors: 1.00 * Foundation weight 1.00 * Soil weight Weight of foundation and soil over it: Gr = 83,62 (kN) Design load:
Nr = 1354,06 (kN) Mx = -45,21 (kN*m) My = -1,29 (kN*m) Stability moment: Mstab = 1286,36 (kN*m)
Rotation moment: Mrenv = 45,21 (kN*m) Stability for rotation: 28.46 > 1
About OY axis
Design combination: ULS A1 : 1.35DL1+1.35DL2+1.35DL3+1.50LL1
Load factors: 1.00 * Foundation weight 1.00 * Soil weight Weight of foundation and soil over it: Gr = 83,62 (kN) Design load:
Nr = 1354,06 (kN) Mx = -45,21 (kN*m) My = -1,29 (kN*m) Stability moment: Mstab = 1286,36 (kN*m)
Rotation moment: Mrenv = 1,29 (kN*m) Stability for rotation: 997.8 > 1
1.3 RC design
1.3.1 Assumptions
Exposure : X0
Structure class : S1
1.3.2 Analysis of punching and shear Punching
Design combination ULS : 1.35DL1+1.35DL2+1.35DL3+1.50LL1+0.75SN1 Load factors: 1.35 * Foundation weight
1.35 * Soil weight Design load:
Nr = 1400,79 (kN) Mx = -45,25 (kN*m) My = -1,30 (kN*m) Length of critical circumference: 4,47 (m)
Punching force: 756,25 (kN) Section effective height heff = 0,33 (m)
Reinforcement ratio: = 0.22 %
Shear stress: 0,67 (MPa)
Admissible shear stress: 0,74 (MPa)
Safety factor: 1.104 > 1
Longitudinal reinforcement A = 7,20 (cm2) A min. = 7,20 (cm2) A = 2 * (Asx + Asy)
2 Material survey:
Concrete volume = 1,66 (m3)
Formwork = 4,48 (m2)
Steel B500C
Total weight = 80,34 (kG)
Density = 48,40 (kG/m3)
Average diameter = 12,2 (mm)
Survey according to diameters:
Diameter Length Number:
(m)
10 2,00 18
12 2,13 13
16 2,07 5
16 2,70 2
16 2,76 2