GGU-FOOTING: Enter system parameters (Example 1)

The appropriate partial safety factors have already been entered into the "Edit/System parameters" menu item. The quantities described below can be entered or edited. Use the default values for the example.

• "Partial FOS (bearing capacity/permanent actions/changeable actions):"/"Bearing capacity FOS [-]:"
  Safety factor according to DIN 4017

• "Groundwater table [m]:"
  Measured from ground level in m

• "Footing base [m]:"
  Measured from ground level in m

• "Slope inclination [°]:"
  Positive values only (= falling slope)

The older version of DIN 4017 did not envisage taking slope inclination into consideration. If you are not investigating slopes in accordance with DIN 4017:2006 (the appropriate check box is deactivated, see below), you should therefore examine the approach for your problem used in "Theoretical principles" as a matter of urgency.
Input of slope inclination here does not represent a substitute for slope stability analysis according to DIN 4084!!!. The program assumes that the slope is stable.

• "Berm width [m]:"
  Measured in m beside the footing

The current issue of DIN 4017 does not envisage consideration of berms. You should therefore examine the "Theoretical principles" for an approach to your problem.

• "Slope to DIN 4017:2006"
  Previous versions of DIN 4017 did not provide for consideration of slopes. We therefore installed or own model for taking slopes into consideration.

• "Preloading [kN/m²]:"
  For settlement analyses, a preloading in kN/m² can be subtracted from the current footing pressure. Settlement analysis will then be performed with the reduced values. The overburden stress is also reduced by this amount when calculating the limiting depth.

• "Surcharge (bearing capacity) [kN/m²]:"
  The bearing capacity surcharge defines a stress on the ground, which generates a stress on the failure body in addition to the embedment depth.

• "Surcharge (limiting depth) [kN/m²]:"
  According to DIN 4019, settlement analysis can be terminated at a depth (limiting depth) in which the stress from soil self-weight and ground surcharges is greater than 20 % of the stresses caused by the footing. You can enter the ground surcharge for this limiting depth calculation, here. Input is only of importance if you calculate the limiting depth as a function of the surcharge stress (see also Section “Select the limiting depth (Example 1)”).

• "H/V [-]:"
  Ratio of the horizontal force H to the vertical force V
  In the bearing capacity equation in DIN 4017, a horizontal force can be taken into consideration. In GGU-FOOTING this force can be defined as a ratio to the vertical force.

• "Calculate using depth coefficients"
  In the bearing capacity equations in DIN 4017, the effects of the shear strength of the soil above the footing base are neglected. According to Section "Theoretical principles: Analysis of bearing capacity failure", this influence can be considered by applying the depth coefficients d_c and d_d. Four different procedures are available, which can be selected via the dropdown menu. The depth coefficient equations can be found in the above-mentioned Section.

• "Friction angle for bearing capacity failure"
  Three of the four depth coefficient equations use a friction angle:
  Check box deactivated ⇒ mean friction angle at footing base will be adopted.
  Check box activated ⇒ friction angle for bearing capacity analysis will be adopted.

• "Depth coefficients for slopes too"
  If the slope inclination ≠ 0, the parameters d_c and d_d are set to "1.0" if the check box is deactivated. If the check box is activated, the influence of the shear strength of the soil above the footing base is also taken into consideration in a slope.

• "Verify bearing capacity for short side only"
  The program verifies the bearing capacity safety for the short and the long sides of the footing. In rare, exceptional cases (see the included file "DIN 4017 new Example 6 a flexible.gdg") it may be expedient to verify the short side only. You should then activate this check box.

• "Limit soil pressure" group box
  For predefined footing types, the program calculates the allowable soil pressure as a function of the footing width. If footing pressures are determined, which are too high for your taste, in particular for large footing widths, possibly due to excessively high settlement or for simple safety reasons (the structural engineer always computes with the allowable values provided by you), you can limit the allowable footing pressure to a defined level. Activate the "Apply" check box and enter the required maximum value.

• "5° condition" group box
  According to DIN 4017 the soil properties can be averaged out for stratified ground. The condition for this is that the averaged friction angle demonstrates a maximum deviation of 5° to the true friction angles. The program checks this condition. If it is not adhered to, a warning signal is given after the analysis. Alternatively, you can have the program reduce all friction angles in stages, which lie above the average value. The size of the reduction is specified with "Decrement [°]". Small decrement values mean long computation times with high precision. A reduction only takes place if the "Check and correct" check box is activated.

• "Ratio changeable/total loads [-]:" group box
  The failure stress is first divided by the bearing capacity partial safety factor. This gives the bearing capacity stress. A further reduction by the partial safety factors for actions is necessary for calculation of an allowable footing pressure or acceptable bearing pressure. In load case 1, e.g., a partial safety factor of gam(G) = 1.35 for permanent loads and one of gam(Q) = 1.50 for changeable loads is demanded. From a ratio of 0.40, for example, a total partial factor results from:

Ratio · 1.50 + (1.0 - ratio) · 1.35 = 1.410

• "Punching analysis" group box
  Punching analysis can be activated here. DIN 4017:2006 describes a new punching analysis method. To use this new analysis method the "Punching analysis using new method (recommended)" check box in the 'File/New' dialog box is activated by default when the program starts. The punching analysis equations given in DIN 4017:2006 differentiate between flexible and rigid footings. Accordingly, you will activate or deactivate the "Flexible footing" check box.