If the allowable bearing pressure must be determined based on various parameters such as footing depth below grade, footing width and footing length, App Settings, Project Settings and Workspace Settings allow user input of allowable bearing pressure values along with these parameters in a tabular format.
Depending on the selected input units, the table is populated with some default values. To override these values simply copy and paste the values from Excel or edit them manually. The allowable bearing pressure value is selected from this table depending on the footing depth below grade, footing width and length configurations if the option to use the tabular input is selected. If there are no default tables, rows may be created using the "+" button and then data added for each row. Alternately, create a single row and then copy and paste values from Excel by clicking on the one row that was created to add multiple rows.
The selection of allowable bearing pressure from the table is made as follows:
Based on the actual footing depth, the closest footing depth below grade from the table is selected. If the actual footing depth below grade is less than the smallest footing depth below grade entry in the table, the smallest footing depth below grade is selected. Then footing width and length dimensions in the table are used to find the closest actual footing width and length dimensions. If there isn't one that matches exactly, the rows with widths and lengths immediately less than and immediately greater than the actual footing dimensions are considered resulting in at most 4 rows that will be looked at in obtaining the allowable bearing pressure. The row with the lowest bearing pressure will be used as the net allowable bearing pressure. If there are no matching values for footing length and width, the footing depth below grade value in the table that closely matches the actual footing depth below grade value will be used to obtain the allowable bearing pressure. The value from the table is also populated in "Allowable Net Bearing Pressure" input available on the Footing Geometry page.
The footing width refers to the Z dimension of the footing and the footing length refers to the X dimension of the footing.
If the allowable bearing pressure cannot be determined from the table for any reason, the net allowable bearing pressure value listed on the Allowables page of Settings is used.
A value manually entered in "Allowable Net Bearing Pressure" on the Footing Geometry page will override all other values that may have been obtained from the Allowables page or the Bearing Pressure table if the checkbox to override the allowable bearing pressure on the Footing Geometry page is checked.
The allowable increase for short term loads specified on the Allowables page of workspace settings will be applied to the allowable bearing pressure value calculated as mentioned above.