Flexure Capacity
The continuous footing flexure capacity is calculated in the same manner as the spread footing. The flexure capacity of the footing is checked from face of column to face of adjacent column or edge of slab.
The required flexure capacity for a section perpendicular to the footing's major axis is recovered from the Finite Element analysis on the beam elements.
- For columns remote from the footing ends: The column strips are calculated as 3 w/4 + 9d/4on either side of the column center line.
- For columns at the ends of the footing another check needs to be considered: 3 w/4 + c
The effective width is taken as the sum of the minimum values of the equations above for either side of the column.
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- Moment arm: L' = w1 - w & w2 - w
- Total Force on section:
- Moment Capacity:
The process is repeated for all columns and all the regions between columns.
The continuous footing's provided flexure capacity is calculated using the same method outlined in "Flexure Capacity" for Spread footings.
The same method is used for areas between adjacent column effective width areas. In both the column effective width areas and the areas in between, if there is any part of the critical area in tension, the program checks to see if the load on the uplift portion of the footing using the footing slab self weight and surcharge controls the value of Mu.