Embedded Pole Constrained/Non-Constrained? 1

[RDR89]

Hi all, I have an embedded pole calculation that I am doing per IBC 1807. My question is do you consider asphalt and crushed stone as rigid constraint at the ground surface? There will be 3" of hot mix asphalt on top of 8" of crushed surfacing top course (all this on top of the compacted subgrade). I know that concrete pavement would be considered rigid but I am not sure about this mix. Any insight is appreciated!

 

[RDR89]

Sorry to jump on this thread again but I didn't want to open a new thread. In what situations do you consider the top 12" of backfill "effective" or not. I've seen it done both ways and, if I read the IBC presumptive load bearing table correctly, it doesn't provide explicit guidance... just that for non-constrained conditions, you only look at resistance in the top third of the embedment depth. I can understand that in practice, one may be unsure of the quality of fill in the top 12" of embedment or need to account for erosion etc. so the top 12" is disregarded for analysis. I guess my question is, at what depth do you start considering resistance based on the presumptive load bearing values given for backfill?

 

[Lomarandil]

RDR89, I'd say the decision to disregard some top depth of fill is more situational and related to the adjacent topography/uses/conditions than anything. If I disregarded the top 12", I'd then consider the top 1/3 of the remaining embedment depth for IBC.

 

[WesternJeb]

1. I have not heard of any engineers I know disregarding the top of fill.
2. We have to expect others to do their jobs correctly, that is a rabbit hole with no end if we start trying to compensate for others to not do their job properly. This includes properly compacting the top of fill.
3. There are so many safety factors involved in our design that items such as this will buff.

 

[Celt83]

It can really depend on what the site conditions are going to be for the pole if this thing is located in a grassy or planting area highly likely the soil gets disturbed throughout the useful life or maybe it is in a brand new parking lot where maybe you do have good compaction, or maybe an old parking lot where the ground looks like a wave pool so maybe not the best soil conditions in that upper stratum, etc. If you are lucky enough to have a Geotech also always worth asking them for a recommendation.