Guide to Design of Footings for Trees
This includes where footings are designed for tree drying effects and where footings are designed for the effects of tree removal or for anticipated tree removal or death.
The main sections in AS2870-2011 are Appendix H and the informative commentary Appendix CH. Guide to Design of Footings for Trees.
To design for tree effects the following Parameters are required for input into CORD:
Ys mm (ys)
Hs mm
Click include tree effects
Click design for tree removal/drying (only applies after you click include for trees)
Yt mm (yt) design tree effect (potential surface movement due to the tree/s)
The input Yt is based on Ytmax . Both Yt and Ytmax are not calculated in CORD and require a separate program incorporating the borelog of the subsurface soils to evaluate Ys and Ytmax. The Ytmax is evaluated based on the Depth of design suction change (Hs), maximum extra suction change and the maximum design drying depth (Ht) for single or tree group (refer to Figure H1 in Appendix H). Once Ytmax is evaluated the value Yt is calculated based on the following parameters – design height of tree/s, distance of tree to the building, and influence distance of the tree/s. Refer to Section H2 Definitions in Appendix H. Section H4 describes the Design Procedure.
CORD 8.0 applies all the Code requirements in the analysis of the footings for tree effects once the inputs described above are entered.