Shoring, reshoring, backshoring, preshoring

[didureadtheplans]

Any know anything about the subject listed.

Background:
I have a structure, 5 stories tall.
ground slab was poured
shoring for 2nd floor installed
2nd floor poured
shoring for 3rd floor installed (shoring from 2nd to ground still in place).
shoring for 4th floor installed (shoring from G to 2nd removed)
4th floor poured.

therefore when the 4th floor was poured shoring was in place from the 2nd to 3rd and from the 3rd to 4th.

the question is:

prior to the 4th floor pour was the 2nd and 3rd floor considered to have deflected and carried there own weights? or since shores were only removed from under the 2nd floor was it only considered to have deflected and carried it's own weight plus the weight of the 3rd floor and the weight of the fresh concrete on the 4th floor.

the floors were not reshored.

 

[BAretired]

I think shores were removed too early although you have not given the time elapsed between events. In my practice, it was customary to maintain re-shores for a minimum of three floors in addition to the floor being poured. The time between pours was usually one week.

That meant that at least three floors were carrying the newly placed concrete. They had cured for 3, 2 and one week respectively. If the contractor managed faster time than a floor a week, he was required to maintain more re-shores.

BA

 

[hokie66]

The time between floor pours would be important, but to answer your question, floors 2 and 3 would be contributing in carrying the load of the fresh concrete on floor 4. How much contribution floor 3 makes is dependent on its maturity.

 

[didureadtheplans]

Prior to the 4th floor pour, the shores beneath the 2nd floor had been removed for approx. 14 days.

When the 4th floor slab was poured the 2nd floor slab was approx. 3 months old and the 3rd floor slab was approx. 2 months old.

the agruement is were the 2nd and 3rd floors over loaded the the time of the ground to 1st floor removal? and would the 3rd floor actually carry load since the shores were never dropped prior to the 4th floor pour (would it been allowed to deflect and carry its own weight prior to the 4th floor pour)?

 

[BAretired]

When shoring was removed under the second floor, the second and third floor had cured for 76 and 46 days respectively. It may be assumed that each of these floors was carrying its own weight after shore removal.

When the fourth floor was poured, the second and third floor had cured for 90 and 60 days respectively and would tend to carry the fourth floor in proportion to their stiffness.


BA