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Construction Tech Review | Thursday, May 23, 2019
FREMONT, CA: Recently, Health and Safety Executive (HSE) analyzed the risk factor from the incidents during demolition work and refurbishment and selected several case studies for the cause. While some of them involved human casualties, others incurred huge expenses that significantly exceeded any savings from shortcuts indicating the structural loopholes.
Below are a few case studies and the best practices to minimize risk factors.
Lack of Enough Pre-Demolition Information
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While demolishing a high-rise building comprising of large precast panels, the client didn’t provide sufficient information. The demolition was being done with the help of high reach demolition machine. However, the poor design and poor interconnection among the precast panels led to the premature collapse of the floors across multiple bays.
The lack of proper assessment and information led to this incident. Fortunately, there were no injuries, but the project was delayed because of the inquiries over the mishap.
Poor Design and Execution of Basement Extension
A new basement was dug out by tunneling underneath a community building. The excavation was carried across the full perimeter of the building. Acrows were underpinned for support, but the sides were not strengthened. The contractor assumed the underlying material to be solid rock, but it was loose shale. As a result, emergency efforts to save the building were made, which made the matter worse. Ultimately the problem led the contractor out of business.
All construction and excavation underneath or close to a building structure must be done after analyzing the surroundings and risk factors involved.
Support from Non-Loadbearing Elements
Structural works were stopped on a masonry building citing its stability. Some of the non-structural window frames were removed. Some of these were supporting to a gable wall. The wall collapsed, killing several people and causing other parts of the building to collapse as well.
Older buildings usually need internal or external support or scaffolding while refurbishing them.
Overloaded Existing Structure
Some of the bricks were cast out of an internal wall for prepared design. He stored the blocks on a suspended timber floor. Due to the additional weight, the floor collapsed injuring several workers.
A temporary work engineer could have advised on how much load was safe and the way to store them to minimize risk.
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