bell tip piles for crane runway

[charliealphabravo]

I am reviewing the design for a proposed steel crane runway (pair of 5 tons) supported by concrete bell tip piles (piers actually). The runway consists of moment frames in the transverse direction (50' span) and x-bracing in the longitudinal direction (24' spacing).

The drawings currently do not show grade beams between the pile caps. I have not seen this before. I also haven't received the calcs yet but can anyone comment on whether this is common practice and if the piles (18"D) and caps can be expected/designed to accept the lateral loads within the usual drift limitations (h/400 I think). The geotech recommendations are also silent on grade beams.

Any literature recommendations for pile foundation design would also be appreciated.

Thanks guys.

 

[msquared48]

I, too, would be concerned, due to the moment frame connection, with lateral spreading of the piers without the presence of grade beams.

The geotech needs gto chime in on this concept, and in writing...

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[charliealphabravo]

The moment frame is shown as pinned at the base/cap connections...but as you say this model assumes that no spreading occurs whereas in actuality the spread depends on the stiffness of the frame.

 

[msquared48]

And the horizontal reaction from the frame will cause the spreading.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[Eldorado]

Granted I don't know the magnitude of your lateral loads, but unless you are drilling into stone right at grade, this doesn't sound like a reasonable design. I might suggest getting L-pile parameters from the geotech and seeing how your lateral loads are resisted, but I think it's just going to confirm that the soils will not adequately resist the loads. My gut tells me the lateral loads in line with your x-bracing will be the most problematic.