Which factor is critical in calculating the stability of a tall structure under lateral wind loads?

The height to width ratio is a critical factor in assessing the stability of a tall structure under lateral wind loads because it helps to determine how susceptible a structure is to bending or overturning due to wind forces. A taller, more slender structure is generally more prone to lateral movement compared to a structure that is shorter and wider. The ratio provides insight into the overall geometry of the building: as the height increases relative to the width, the center of mass may shift higher, increasing the impact of wind loads. This relationship guides engineers in designing appropriate bracing systems or other stabilization methods to mitigate potential lateral movements and ensure the structure's safety and performance during high wind events.

The other factors, while important in various contexts of structural design, do not directly address the specific interaction of the geometry with lateral wind loads in the same way. The floor area ratio relates to zoning regulations and building density rather than stability. Concrete density influences material strength and weight but does not inherently determine how a structure reacts geometrically to lateral loads. Material strength is crucial for ensuring that components can withstand stresses, but without optimal height to width considerations, even strong materials may not satisfactorily prevent instability in high winds.