PSI - Issue 84

Ahmed Amir Khalil et al. / Procedia Structural Integrity 84 (2026) 1031–1038

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The AEM capabilities to follow the structural behavior under extreme loads and large deformations up to the failure and element separation, Meguro et al. (2000, 2001, 2002), Tagel-Din et al. (2004), are also employed to evaluate the collapse sequence of the structure to see possible premature failures in some areas and to estimate the debris spread and height of the collapsed building on the ground. Figure 7 presents a side-by-side comparison of the collapse sequence predicted by the AEM simulation and the actual observed case. 4.2. Reinforced concrete stack The ELS simulation of the RC stack, when applying the blast up to 65% of the circumference, shows a significant vertical drop. Initially the structure moves horizontally as planned, then after 2.5 sec. starts to move with a relevant vertical component for about 60 m. The stack hits the ground with a deviation of about 30 degrees from the desired fall direction, see Figure 8. To reduce the damage in the lower portion of the outer RC shell and consequently reduce the vertical drop, the blast area is decreased to 55% of the stack circumference, and five steel props (H beam 40 cm x 40 cm) are installed to strengthen the construction opening in the backside (opposite to the fall direction). The AEM simulation with the demolition scenario modifications proposed, shows a reduced vertical drop with a deviation angle from the desired direction of about 7 degrees. Figure 9 shows a side-by-side comparison of the two stack simulations with initial and refined demolition plan. The scenario optimization provides better results in terms of collapse sequence reducing the risk of uncontrolled structural failure.

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Fig.8 (a) vertical displacement of the RC stack roof, (b) plan view of the collapsed shape and deviation angle

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Fig.9 Side view of the collapse sequence, (a) initial demolition scenario 65% blast, (b) optimized demolition scenario 55% blast and steel props added