Miami Beach, Champlain Towers South apartment building collapse, Part 11 54

[SFCharlie]

A continuation of our discussion of this failure. Best to read the other threads first to avoid rehashing things already discussed.
Miami Beach, Champlain Towers South apartment building collapse
Miami Beach, Champlain Towers South apartment building collapse, Part 02
Miami Beach, Champlain Towers South apartment building collapse, Part 03
Miami Beach, Champlain Towers South apartment building collapse, Part 04
Miami Beach, Champlain Towers South apartment building collapse, Part 05
Miami Beach, Champlain Towers South apartment building collapse, Part 06
Miami Beach, Champlain Towers South apartment building collapse, Part 07
Miami Beach, Champlain Towers South apartment building collapse, Part 08
Miami Beach, Champlain Towers South apartment building collapse, Part 09
Miami Beach, Champlain Towers South apartment building collapse, Part 10


SF Charlie
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[SFCharlie]

PLEASE STOP POSTING IN THIS PART 11 PLEASE
Please allow me to move the discussion to Miami Beach, Champlain Towers South apartment building collapse, Part 12, Thank-you.
Someone Please close this post to new postings, or message me how to do this, Thanks.

SF Charlie
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[Vance Wiley]

It has been mentioned earlier that some contractors placed slab pours to the level of the bottom of the upper reinforcing and stopped there to lay the upper reinforcing on the concrete and avoid the use of high chairs. This would require a delay for the slab to set for foot traffic and to support the reinforcing.
The proper casting of a concrete member - beam, column, slab, footing, or wall is monolithic - one casting with reconsolidation between the layers of placement - or through a properly prepared cold joint.
Had I caught a contractor leaving an as placed joint surface in concrete he would have been sandblasting the entire surface to remove the interface surface sufficient to expose aggregates solidly embedded in the prior pour. That is a bit expensive.
On one project the contractor did not place the temperature reinforcing in a topping slab which was placed over precast tees. The flanges of the tees had been intentionally roughened just like DOT girders and were correctly prepared for a topping slab placement. The contractor should have called for an inspection. The remaining pile of reinforcing was the clue. He was directed to place the reinforcing, clean the slab, and coat the surface with epoxy. The reinforcing was temperature reinforcing - not the principal reinforcing providing strength for floor support, as the reinforcing of slabs at CTS was.
Cold joints were a problem at FIU. What is with the Florida contractors?
The concrete is/was likely mixed in a batching plant and trucked to the site. It might have been pumped or perhaps hoisted in buckets to the elevation being placed if there were a crane on the site. The handling of concrete, even in the 1980s, was clearly defined in the codes and industry practice. Batch times, number of turns of the drum on the truck, slump, added water - all are supposed to be controlled. Mixes are and were designed and load tags provided with reference to specific approved mixes, and the concrete sampled for slump and compressive strength. And it remains a problem today.
Reinforced concrete is the most structurally important product in most structures that is actually created on the job. Under less than factory controlled conditions - like rain, temperature, and other factors. But on the job it becomes just hard work, with a deadline only an hour away if you want to finish it correctly.
Thanks,

 

[Jacob Henry]

what a disaster,

https://mwi.solutions/technologies/wms-wcs-and-oms-software/

 

[SFCharlie]

We are over on part 12. If this is just an ad, it might be removed.
Please let us know why you thought to post this link over on part 12 to help us understand why you suggested it, Thanks


SF Charlie
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