The Critical Role of Non-Structural Components in Earthquake Resilience

Introduction

While structural integrity is crucial during an earthquake, non-structural components often account for the majority of damage and associated costs in seismic events. This page explores the importance of securing non-structural elements, the economic implications of their failure, and strategies to enhance resilience, supported by examples from past earthquakes.

Understanding Non-Structural Components

Non-structural components include all the parts of a building that are not part of the structural system. This includes:

  • Architectural elements: Ceilings, partitions, and exterior cladding.

  • Mechanical, electrical, and plumbing systems: HVAC systems, electrical conduits, water heaters, and plumbing.

  • Contents and furnishings: Office equipment, furniture, appliances, and shelving units.

Economic Impact and Downtime

During an earthquake, damage to non-structural components can lead to significant economic losses and operational disruptions. Key impacts include:

  • Repair and Replacement Costs: Often exceeding the costs to repair structural damage due to the widespread nature of non-structural failures.

  • Business Interruption: Damage to operational systems like power and water, or machinery can halt production lines, disrupt services, and lead to loss of revenue.

  • Recovery Time: Extensive damage to interior spaces can lead to longer recovery times as repairs and replacements of systems and contents are carried out.

Historical Examples of Non-Structural Damage

  1. 1994 Northridge Earthquake:

    • Extensive damage to non-structural components such as fallen ceiling tiles and broken fixtures significantly contributed to the $44 billion in total damages.

    • Hospitals and commercial buildings experienced major disruptions due to damaged contents and systems.

  2. 2011 Christchurch Earthquake:

    • The earthquake highlighted the vulnerability of non-structural elements in office buildings, where the collapse of partitions and ceilings caused major obstacles to reoccupation.

    • Economic losses were exacerbated by the downtime needed to restore office spaces and retail environments.

  3. 2010 Chile Earthquake:

    • Despite relatively strong building structures, the failure of non-structural elements like façade panels and internal fittings led to prolonged business interruptions.

Mitigation Strategies

Securing non-structural components is a cost-effective way to enhance overall building resilience. Effective strategies include:

  • Flexible Mounting of Equipment: Using vibration isolators and flexible mounts to secure HVAC units and other heavy equipment.

  • Anchoring and Bracing: Installing anchors for shelves, cabinets, and machinery to prevent tipping and sliding.

  • Strengthening Ceilings and Partitions: Reinforcing suspended ceilings and lightweight partition walls to prevent collapse.