Interstory drift

Definition

Interstory drift refers to the relative lateral displacement between two adjacent floors of a building during seismic activity or lateral loading. This phenomenon is crucial to understand because excessive interstory drift can lead to structural damage, compromised safety, and failure of non-structural components within a building. It is particularly significant in the design and evaluation of buildings with respect to their performance during earthquakes, especially when considering supplemental damping devices that can help mitigate such movements.

5 Must Know Facts For Your Next Test

1. Interstory drift is typically quantified as a ratio of the lateral displacement to the height of the story being considered, expressed as a percentage.
2. Building codes often limit the allowable interstory drift to ensure that structures remain functional and safe during and after seismic events.
3. Supplemental damping devices are designed to absorb and dissipate energy from seismic forces, reducing interstory drift and improving a building's overall performance.
4. Excessive interstory drift can lead to severe damage to non-structural elements such as walls, ceilings, and partition systems, which may collapse or create hazards.
5. Monitoring interstory drift is essential for evaluating the effectiveness of retrofitting measures in older structures that may not have been designed with modern standards in mind.

Review Questions

• How does interstory drift affect the overall stability of a building during an earthquake?
  • Interstory drift significantly impacts a building's stability during an earthquake by causing relative lateral movement between floors. When one floor shifts more than another, it can create torsional forces that may compromise structural integrity and lead to failure. Understanding this concept is vital for engineers when designing structures that can withstand seismic forces without suffering excessive drift that could endanger occupants or cause damage.
• Discuss how supplemental damping devices can be used to manage interstory drift in seismic design.
  • Supplemental damping devices play a critical role in managing interstory drift by absorbing seismic energy and reducing the lateral displacements between floors. These devices, such as tuned mass dampers or viscous dampers, are strategically placed within a structure to counteract forces that would typically cause significant drift. By integrating these damping systems into the design, engineers can enhance the building's performance during earthquakes, ensuring safety and minimizing damage.
• Evaluate the importance of controlling interstory drift in the context of modern building codes and engineering practices.
  • Controlling interstory drift is crucial in modern engineering practices due to its direct correlation with life safety and structural integrity during seismic events. Building codes are increasingly stringent regarding allowable drift limits, which reflects the understanding that excessive drift not only damages structural elements but also non-structural components that can pose safety risks. As engineers design new structures or retrofit older ones, ensuring compliance with these codes while effectively managing interstory drift has become a fundamental aspect of achieving resilience against earthquakes.

Related terms

Seismic response: The reaction of a structure to seismic forces, including both lateral movements and vertical accelerations that occur during an earthquake.

Lateral stiffness: The resistance of a building structure to lateral forces, which directly influences how much interstory drift occurs under seismic loads.

Damping systems: Devices or methods used to reduce the amplitude of vibrations in a structure, thereby decreasing interstory drift and improving overall stability during seismic events.