Resilience (engineering and construction)
In the fields of engineering and construction, resilience is the ability to absorb or avoid damage without suffering complete failure and is an objective of design, maintenance and restoration for buildings and infrastructure, as well as communities. A more comprehensive definition is that it is the ability to respond, absorb, and adapt to, as well as recover in a disruptive event. A resilient structure/system/community is expected to be able to resist to an extreme event with minimal damages and functionality disruptions during the event; after the event, it should be able to rapidly recovery its functionality similar to or even better than the pre-event level.
The concept of resilience originated from engineering and then gradually applied to other fields. It is related to that of vulnerability. Both terms are specific to the event perturbation, meaning that a system/infrastructure/community may be more vulnerable or less resilient to one event than another one. However, they are not the same. One obvious difference is that vulnerability focuses on the evaluation of system susceptibility in the pre-event phase; resilience emphasizes the dynamic features in the pre-event, during-event, and post-event phases.
Resilience is a multi-facet property, covering four dimensions: technical, organization, social and economic. Therefore, using one metric may not be representative to describe and quantify resilience. In engineering, resilience is characterized by four Rs: robustness, redundancy, resourcefulness, and rapidity. Current research studies have developed various ways to quantify resilience from multiple aspects, such as functionality- and socioeconomic- related aspects.
The built environment need resilience to existing and emerging threats such as severe wind storms or earthquakes and creating robustness and redundancy in building design. New implications of changing conditions on the efficiency of different approaches to design and planning can be addressed in the following term.
Engineering resilience has inspired other fields and influenced the way how they interpret resilience, e.g. supply chain resilience.
Etymology
According to the dictionary, resilience means "the ability to recover from difficulties or disturbance." The root of the term resilience is found in the Latin term 'resilio' which means to go back to a state or to spring back. In the 1640s the root term provided a resilience in the field of the mechanics of materials as "the ability of a material to absorb energy when it is elastically deformed and to release that energy upon unloading". By 1824, the term had developed to encompass the meaning of ‘elasticity’.19th century
was the first to introduce the concept of resilience in 1818 in England. The term was used to describe a property in the strength of timber, as beams were bent and deformed to support heavy load. Tredgold found the timber durable and did not burn readily, despite being planted in bad soil conditions and exposed climates. Resilience was then refined by Mallett in 1856 in relation to the capacity of specific materials to withstand specific disturbances. These definitions can be used in engineering resilience due to the application of a single material that has a stable equilibrium regime rather than the complex adaptive stability of larger systems.20th century
In the 1970s, researchers studied resilience in relation to child psychology and the exposure to certain risks. Resilience was used to describe people who have “the ability to recover from adversity.” One of the many researchers was Professor Sir Michael Rutter, who was concerned with a combination of risk experiences and their relative outcomes.In his paper Resilience and Stability of Ecological systems, C.S. Holling first explored the topic of resilience through its application to the field of ecology. Ecological resilience was defined as a "measure of the persistence of systems and of their ability to absorb change and disturbance and still maintain the same relationships between state variables." Holling found that such a framework can be applied to other forms of resilience. The application to ecosystems was later used to draw into other manners of human, cultural and social applications. The random events described by Holling are not only climatic, but instability to neutral systems can occur through the impact of fires, the changes in forest community or the process of fishing. Stability, on the other hand, is the ability of a system to return to an equilibrium state after a temporary disturbance. Multiple state systems rather than objects should b studied as the world is a heterogeneous space with various biological, physical and chemical characteristics. Unlike material and engineering resilience, Ecological and social resilience focus on the redundancy and persistence of multi-equilibrium states to maintain existence of function.
Engineering resilience
Engineering resilience refers to the functionality of a system in relation to hazard mitigation. Within this framework, resilience is calculated based on the time it takes a system to return to a single state equilibrium. Researchers at the MCEER have identified four properties of resilience: Robustness, resourcefulness, redundancy and rapidity.- Robustness: the ability of systems to withstand a certain level of stress without suffering loss of function.
- Resourcefulness: the ability to identify problems and resources when threats may disrupt the system.
- Redundancy: the ability to have various paths in a system by which forces can be transferred to enable continued function
- Rapidity: the ability to meet priorities and goals in time to prevent losses and future disruptions.
Social-ecological resilience
Applications
International Building Code
The international building code provides minimum requirements for buildings using performative based standards. The most recent International Building Code was released in 2018 by the International Code Council, focusing on standards that protect public health, safety and welfare, without restricting use of certain building methods. The code addresses several categories, which are updated every three years to incorporate new technologies and changes. Building codes are fundamental to the resilience of communities and their buildings, as “Resilience in the built environment starts with strong, regularly adopted and properly administered building codes” Benefits occur due to the adoption of codes as the National Institute of Building Sciences found that the adoption of the International Building Code provides an $11 benefit for every $1 invested.The International Code Council is focused on assuming the community's buildings support the resilience of communities ahead of disasters. The process presented by the ICC includes understanding the risks, identifying strategies for the risks, and implementing those strategies. Risks vary based on communities, geographies and other factors. The American Institute of Architects created a list of shocks and stresses that are related to certain community characteristics. Shocks are natural forms of hazards, while stresses are more chronic events that can develop over a longer period of time. It is important to understand the application of resilient design on both shocks and stresses as buildings can play a part in contributing to their resolution. Even though the IBC is a model code, it is adopted by various state and governments to regulate specific building areas. Most of the approaches to minimizing risks are organized around building use and occupancy. In addition, the safety of a structure is determined by material usage, frames, and structure requirements can provide a high level of protection for occupants. Specific requirements and strategies are provided for each shock or stress such as with tsunamis, fires and earthquakes.