Superimposed dead load for vegetation, shrubs, small trees, etc.? 2

[bugbus]

I am looking at a buried structure with landscaping and vegetation on top. The plants will sit in concrete planters with a well controlled depth of fill, so the weight of the soil is well accounted for.

But the weight of the vegetation doesn't seem to be addressed anywhere in particular, so I'm wondering if anyone has experience?

This would include various plants, shrubs, grass, and small trees (up to about 3-4 metres high). So far, this has been considered as a 0.5 kPa superimposed dead load with load factor of 2.0. Does that seem appropriate?

I should also mention that the landscaping will be routinely tended to, and the trees can only grow so high before they would start clashing with other parts of the structure, so there is no risk of these growing uncontrollably.

 

[HTURKAK]

I am not familiar with your local applicable code ..but in order to give an ides , i copy and pasted the relevant clause (cl.2.1(3)P-cl.2.1(3)P) of EC- 1991-1-1

(earth loads (e.g. for roof gardens) the self-weight will vary with time
‘due to variations in moisture content and variation in depth, that may be caused by uncontrolled
accumulation during the design life of the structure’ and these should be considered in the design..)

- EC assumes roof gardens soil loads are permanent loads

- the soil wt should be soaked unit wt...

IMO, 0.5 kPa superimposed dead load for only shrubs, trees ( except soil, roof LL etc) is reasonable..

 

[Tomfh]

For small trees 3-4m it won’t be much. Say you have 150mm diameter trunks, average 3m high at 1m cts, that’ll be close to your 0.5kPa.

Are you adding a regular live load onto the soil too, in additional the vegetation SDL?

 

[To Madeira]

Table A-4 and A-5 in the attached document have some information on weight of trees and shrubs.

 

[bugbus]

Thanks all, very helpful

Yes, live loading is considered in addition to the vegetation

 

[GeorgeTheCivilEngineer]

I'd have thought the live load would suffice - where there is a shrub, there isn't a person.

 

[dik]

To Madeira... excellent reference, thanks.

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-Dik