Geotechnical Verification – Eurocode & NTC
This dialog box contains the following options:
The Geotechnical Verifications dialog box
Sliding verification
Design friction angle: you are allowed to define design friction angle value (δ) as ϕ’crit (according to 10.1(6)NFP94-261) or ϕ’crit multiplied by a factor.
Eccentricity verification
The ability of a spread foundation to carry forces reduces dramatically when those forces are applied eccentrically from the center of the foundation. To prevent contact with the ground being lost at the footing’s edges, it is customary to keep the value of the compressed footing area (effective area) over a minimum value.
Note: Special precautions shall be taken where the eccentricity of loading exceeds 1/3 of the width of a rectangular footing […]. [EN 1997-1 §6.5.4(1)]
The effective area of spread foundation
In this section you can define the percentage value to be considered for the minimum footing area in compression:
Compressed eccentricity verification
Activate: check this option to activate the compressed surface verification for each limit state. The compressed surface is calculated geometrically, as a polygon area. For Rectangular contact pressure distribution, the area of the polygon is (1-2|ex|/A)* (1-2|ey|/B). As a result, only for Rectangular pressure distribution, the eccentricity verification for France localization according to NF P94-261, will be the same thing with the compressed surface verification if the default limits are kept (7%=1/15, 67%=2/3, 50%=1/2). For Linear and Uniform contact pressure distribution there will be no corresponding formula for eccentricity verification so it will only be verified if the compressed area is bigger than the limit.
ULS (FUN/ACC/SEI): enter a percentage for the footing area in compression for ultimate limit states (fundamental, accidental, seismic).
SLS (QPR/FRQ): enter a percentage for the footing area in compression for serviceability limit states (quasi-permanent, frequent).
SLS (CHR): enter a percentage for the footing area in compression for serviceability limit state (characteristic).
Simplified eccentricity verification
Activate: check this option to activate the load eccentricity verification considering the Elipse of the Central core formula.
Consider during preliminary sizing: check this option to ensure the passing of eccentricity verification during preliminary sizing
Overturning EQU verification
Activate: check this option to verify the footing's stability for overturning.
Safety factor: enter the value of the factor of safety against overturning.
Settlement SLS verification
Activate: check this option to generate a settlement analysis for the serviceability limit state (SLS) using one of the available methods.
Method: select one of the available methods from the drop-down: Elasticity, Vertical Strains, Pressuremeter.
Allowable settlement: enter a value for the maximum allowable settlement.
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