According to structural engineer Rob Clarke, for demolition experts Controlled, "The similarities between the predicted collapse and the actual collapse were impressive."
"We removed the end elevation masonry panels and pre-weakened the side elevation columns to encourage hinge formation. The suspended ground floor slab connection at the top of the basement retaining wall was removed in order to protect the wall from being pulled in as the slab drops.
"An earth bund was formed against the inside face of the wall to balance the earth pressures. We estimated the hidden design parameters, such as reinforcement amounts and details, joint stiffness, etc. This information was added to the 3D model to give a fairly close representation of the actual pre-weakened structure.
"It took two days to build the model and then another two days to run the program. Extreme Loading by ASI calculated the freefall trajectory of each structural element and the interface forces between adjacent elements, both connected and separated, something which Finite Element Analysis is just not capable of," he said.