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Structure failure (collapse of sky line plaza)

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In 1973 one of skyline plaza collapsed. 14 workers died, and 34 were injured as a result of the tragic failure of the structure. The construction of the building was not completed at the time of the collapse, and the building was not due to open until six months. The primary reason behind the failure of the sky is the wrong practices in the field. There was no flaw in the design, and the structural collapse would be easily avoided if the contractors, engineers, and supervisors follow project specifications, guidelines, and correct construction practices.
Figure 1
The investigations showed that the shoring or falsework that supporting the 23rd floor was removed. At the time of removal, the concrete of columns and floors didn’t attain the designed strength. At the same time, more concrete placed for the 24th floor, which overload the columns. The columns couldn’t bear the weight of the 24th floor. The placing of concrete for the 24th-floor prompts the failure and buckling of columns. The heavyweight of the failed floor imposed a huge load on the next floor. The building was not designed to withstand such huge loads, which prompt a consequence failure of building floors.

Figure 2

Concrete possesses a low strength at the time of placing. Therefore, the formwork used to mold the concrete to the required shape, and falsework or shoring will support the concrete until it gains sufficient strength. Concrete hardens and gains strength through hydration reaction. Rate of hydration depends on various factors such as climate, type of cement, admixture, pozzolans. Concrete will harden and gain strength faster in hot weather.
On the other hand, concrete will harden slowly if low heat hydration cement used. The designer will determine the compressive strength of concrete, which is sufficient to withstand the expected loads such as dead load and live load. During the construction stage, the structure will be subjected to dead load and construction loads. Before removing formwork and falsework, we should ensure that the concrete gains strength at least twice the imposed loads. The verification can be done by testing cubes or cylinders of concrete sampled from the same mix. If the concrete gains the required strength, the formwork can be removed.

The collapse of skyline buildings would easily be prevented. Engineer. In my opinion, the potential reasons for structure failure are:

· Lack of experienced engineers, supervisors.

· the pressure exerted to complete the work on time, and this resulted in wrong practices such as the removal of formwork rapidly and before the concrete gain strength.

· Negligence by engineers by not carrying out the inspections before removing the formwork. Engineers should stop any activities if he feels it jeopardizing the safety of workers and structure.

· Incorrect work practices: the main reason that causes the collapse of this structure is incorrect work practices and specifically the removal of shoring at an early stage without checking the strength of concrete and considering the loads imposed on the structure. 





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