Resilience

Resilience is often colloquially described as ‘the ability to bounce back’ after a disaster or mishap.

In the face of the diverse range of hazards it is exposed to, a resilient community or society will have developed abilities to:

• Successfully mitigate against prospective hazards

• Prepare for disaster event scenarios

• Resist the effects of disaster events

• Respond to these effects

• Recover from such effects in a timely and efficient manner

Societal resilience is achieved through the preservation and restoration of essential functions provided by the built environment and societal organisation.

Effective preparatory risk management is essential for identifying potential hazards and threats. It can facilitate development of appropriate abilities before an extreme event, which aid an adequate response to events and help with successful recovery from them. It also allows for adaption to evolving requirements and the effects of a changing environment.

It is important to note that recovery may possibly involve some degree of short-term functional impairment. This depends upon the severity of the shock or mishap experienced. It can also be influenced by any economic (or other) constraint which might apply.

The resilient society

A resilient community or society aspires to have the ability to do several things. Firstly, it must be able to effectively mitigate against a prospective disaster. Mitigation means taking measures which avoid, reduce, resist and aid recovery from extreme short-term events or incidents. These include:

• Seismic events

• Flooding

• Tsunami

• Extreme weather events

• Drought

• Landslides

• Volcanic events

• Disease outbreaks

• Transport disasters

• Explosions

Secondly, a resilient community or society must be able to adapt to longer-term changes in use, environment or other circumstances. Examples of this would be societal changes or the effects of climate change. Successful adaption means that:

• Potential hazards and threats are identified and evaluated. This should be done by using effective preparatory risk management and vulnerability assessment procedures

• Appropriate preparatory activities are undertaken. These are used to mitigate, prepare for, resist, respond to and recover from an extreme event or incident. They should allow for adaption to longer-term evolution in requirements, a changing environment, potential hazards, threats and identified vulnerabilities

• Appropriate societal, economic and environmental resources are available to implement the preparatory activities and response actions

Structural engineers are vital to the development of resilient societies. Their role is to consider and address the issues associated with structural resilience and structural adaptation.

The role of structural resilience

Structural resilience is the ability to rapidly resume the use of buildings and structures following a shock incident or event. To successfully do this, it is essential to embrace all the associated aspects of:

• Avoidance, diminution or removal of identified threats or hazards

• Preparation for disaster event scenarios

• Resistance to the effects of disaster events

• Recovery following such an event

Structural resilience needs to encompass:

• The ability to rapidly recover functionality following a short-term shock or extreme event

• All the aspects of preparation for and recovery following such a shock event, as listed above

• Appropriate design for life safety and environmental protection, eg by addressing disproportionate collapse requirements

• Appropriate damage limitation design to reduce the need for repairs or reconstruction after a shock or extreme event. This effectively reduces the life-cycle environmental impact of the building or constructed asset and improves life-cycle sustainability

• Recognition of the spectrum of severity of potential events in the context of causing disruption to the intended social function of the structure. The time and effort involved in recovering from such events should also be considered

• Recognition of the spectrum of severity of potential extreme events in the context of posing significant life-safety risks and resulting in associated damage. The extended time and effort involved in recovering from such events should also be considered. This might include possible partial or total demolition and reconstruction

• Design to facilitate both maintenance and recovery works

The role of structural adaptation

Structural adaptation is the ability to meet gradually changing circumstances or the evolution of performance requirements. It needs to encompass the ability of a system or structure to sustainably accommodate such changing circumstances.

Longer-term adaptions might include changing demands placed upon a structure. They might relate to ongoing environmental changes and evolving societal and functional needs and performance requirements.

Key focus areas for structural engineers include:

• Human safety and environmental protection

• Damage limitation design to facilitate the rapid resumption of use of structures after a disaster

• Climate emergency

• Urbanisation, including the development of megacities

• Responding to humanitarian crises and natural hazards

• International development

• Efficient and effective resource use

• Mitigating the effects of terrorism