【Haichuan Civil Engineering Issues】Do you know about pouring concrete in multi-story buildings using the 2-top-1/3-top-1 method?
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This is a common occurrence on construction sites: in order to facilitate material turnover and save costs, the contractors or labor companies may, despite all rules and regulations, secretly allow the carpenters to remove elements such as the floor beams and horizontal supports that they consider unimportant, before the upper layer of concrete has been poured. Usually, when supervision teams discover this, they immediately intervene, demanding a report on the removal of these elements or requiring that everything be restored to its original state. Yet this often doesn’t help, and it ends up causing tension among all parties involved in the project
Since the upper layer of concrete has not been poured, the full-scale scaffolding on the lower layer must remain completely immobile; it’s not possible to move it even when the strength of the lower layer’s concrete reaches 100%. This is what people refer to as using two layers of support for one layer, or even three layers of support for one layer. This is because the sum of the upper-layer concrete, rebar, temporary materials, construction loads, vibrations, and other such forces is far greater than the XX/㎡ design load that the lower floor is intended to bear. Therefore, everyone must remember not to rush in future construction activities due to schedule pressures or material turnover; one should not remove any of the members of the full-scale support structure on the lower level before the concrete for that level has been poured