Under what condition is torsional irregularity identified?

Torsional irregularity is identified when the maximum storey drift exceeds 1.2 times the average of the storey drifts. This condition indicates an uneven distribution of lateral forces within the structure, which can lead to torsional effects during seismic events or heavy wind loads.

In structural design, particularly for buildings, ensuring a regular distribution of mass and stiffness is crucial to minimize torsional effects. When the maximum storey drift is significantly higher than the average, it implies that certain parts of the building are experiencing disproportionately large movements compared to others, which could compromise the structure's integrity and performance during dynamic events.

This understanding is vital in the assessment and design of buildings to ensure they can adequately resist torsion and maintain structural stability, thus safeguarding against potential failure modes associated with torsional responses.