How to find the shear force of a concrete pile(Shanghai Bldg Collapse)
How to find the shear force of a concrete pile(Shanghai Bldg Collapse)
(OP)
Hi all,
I'm trying to model the Lotus Riverside Apartment building collapse in Shanghai, China using Slope/W. It appears that the building used 2' circle open-ended lightly reinforced concrete piles. Is there any quick way to calculate the shear force of these piles so I can best represent them in SLOPE/W. Plus, any additional information pertaining to the collapse would be greatly appreciated.
I'm trying to model the Lotus Riverside Apartment building collapse in Shanghai, China using Slope/W. It appears that the building used 2' circle open-ended lightly reinforced concrete piles. Is there any quick way to calculate the shear force of these piles so I can best represent them in SLOPE/W. Plus, any additional information pertaining to the collapse would be greatly appreciated.





RE: How to find the shear force of a concrete pile(Shanghai Bldg Collapse)
RE: How to find the shear force of a concrete pile(Shanghai Bldg Collapse)
RE: How to find the shear force of a concrete pile(Shanghai Bldg Collapse)
RE: How to find the shear force of a concrete pile(Shanghai Bldg Collapse)
Try looking up "spun pile" on the internet.
RE: How to find the shear force of a concrete pile(Shanghai Bldg Collapse)
After seeing the site, it seems strange since the adjacent structures had no apparent distress and the problem could be related to the conditions/loads applied later that could include soil, drainage and moisture.
With some familiarity with the massive projects going on concurrently, I would think it is a "cookie cutter" design of similar or identical buildings with the same materials from the same plants within a one year or so period (24x7 construction).
Only an observation.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: How to find the shear force of a concrete pile(Shanghai Bldg Collapse)
RE: How to find the shear force of a concrete pile(Shanghai Bldg Collapse)
Also, consider the possibility that there was no slope failure; instead, the piles on the side toward the excavation may have buckled and the building simply fell over. The combination of the excavation and the softening of the soil from heavy rain may have drastically reduced the lateral confinement that those lightly reinforced piles were relying on to resist buckling. Sometimes you need to think like a structural engineer.
DRG
RE: How to find the shear force of a concrete pile(Shanghai Bldg Collapse)
RE: How to find the shear force of a concrete pile(Shanghai Bldg Collapse)
RE: How to find the shear force of a concrete pile(Shanghai Bldg Collapse)
I strongly believe that if they supported the garage excavation slope, it might have prevented this collapse. The support would of kept the confining pressures around the foundation, allowing the pile to keep the building upright. There is a picture of the adjacent apartment building with the garage excavation in front, however there appears to be some kind of reinforced wall, perhaps a concrete retaining wall. This adjacent building still remains standing. (By the way, the assistant to the lead investigator specifically mentioned that there was no structure created to support the slope.) What do you all think about this?
RE: How to find the shear force of a concrete pile(Shanghai Bldg Collapse)
The slope for the garage exc wouldn't actually need to slide if they simply got it too close to the piles and the soil was soft enough. I saw some "cartoons" of how it happened (NOT photos or engineering drawings) showing the exc going almost right up to the building and being pretty steep.
Regardless, yes, what you describe is an entirely reasonable mechanism, with the main question being whether there was lateral movement of the building before the piles began to fail, or whether the ones closest to the exc just failed due to axial load alone. Buckling, rather than slope instability, has been my leading hypothesis for the initial failure since soon after it happened. However, without some form of stability analysis and viewing it from pictures only, I didn't want to totally write off lateral movement driven by the stockpile on the side away from the exc. We'll never know for sure, since whatever evidence that survived removal of the structure may have been inconclusive, and it probably got quickly s___-canned anyway. I think I read that people are doing hard time in prison.
Having seen some construction sites in China (from a safe distance!), they seem to be a bit more casual about worker safety than we are here.
RE: How to find the shear force of a concrete pile(Shanghai Bldg Collapse)
RE: How to find the shear force of a concrete pile(Shanghai Bldg Collapse)
jwripple,
On the "soil strength and slope stability" book by Duncan, in page 258, there are in details several authors which have been working on evaluating the shear forces and moments in the piles for slope stabilization. Among them: Poulos (1995), Yamagami (2000) and Reese and Van Impe (2001).
Reese and Van Impe use p-y analisys in order to obtain the driving force acting on the pile. It doesn't seem a quick way nor friendly either.
Also, in your SLOPE/W model, it seems you are missing the shear force (i don't see the arrow/symbol). SLOPE/W models the shear force acting on the pile against the sliding surface.
What about the bending moment?, did you finally take it into account for your slope stability analisys?, I really don;t understand where do I need to included it, other than using in order to determine the number of bars for the final pile section.
FixedEarth, you provided an approach of computing lateral restraint force under clay. Do you know an approach for c-phi soil?, any references?