۱- Introduction

۲- Conceptual definitions

۳- Bibliometric details

۴- Progressive collapse and structural robustness in international codes

۵- Quantification of structural robustness

۶- Progressive collapse risk

۷- Experimental testing

۸- Numerical modelling

۹- Conclusions and needs

References

Abstract

Extreme events (i.e. terrorist attacks, vehicle impacts, explosions, etc.) often cause local damage to building structures and pose a serious threat when one or more vertical load-bearing components fail, leading to the progressive collapse of the entire structure or a large part of it. Since the beginning of the 21st century there has been growing interest in the risks associated with extreme events, especially after the attacks on the Alfred P. Murrah Federal Building in Oklahoma in 1995 and on the World Trade Center in New York in 2001. The accent is now on achieving resilient buildings that can remain operational after such an event, especially when they form part of critical infrastructures, are occupied by a large number of people, or are open to the public. This paper presents an ambitious review that describes all the main advances that have taken place since the beginning of the 21st century in the field of progressive collapse and robustness of buildings. Widely diverse aspects are dealt with, including: (1) a collection of conceptual definitions, (2) bibliometric details, (3) the present situation and evolution of codes and design recommendations, (4) quantification of robustness, (5) assessing the risk of progressive collapse, (6) experimental tests, (7) numerical modelling, and (8) research needs. Considering the comprehensive range of these aspects, this paper could be of great use to professionals and researchers who intend to enter the field of the progressive collapse of building structures and also to other experts who require an extensive and up-to-date view of this topic.

Introduction

All types of public and private buildings may be subjected to extreme events, caused, for example, by hurricanes, tsunamis, earthquakes, explosions, vehicle impacts, fires and human errors, or even terrorist attacks. Such events usually cause local damage to the structure of buildings, which can lead to a complete collapse. This is where the term progressive collapse comes in, understood as the process by which local damage sets in motion a chain of failures, leading to the collapse of the entire building or a large part of it. A progressive building collapse is always accompanied by serious personal and material losses [1]. In recent years the press has spotlighted a number of notorious progressive collapses; the most important for the numbers of victims, extent of the damage or social impact at the time include the classics Ronan Point (London, 1968) and Capitán Arenas (Barcelona, 1972), the U.S. Marine Barracks (Beirut, 1983), the Argentine Israelite Mutual Association (Buenos Aires, 1994), the A.P. Murrah Federal Building (Oklahoma, 1995), the Sampoong Department Store (Seoul, 1995), the buildings of the World Trade Center (New York, 2001), and the Achimota Melcom Shopping Centre (Acra, 2012). From the attention given to these and many other collapses, the idea has become generally accepted that there is a need for robust buildings that can sustain local damage without suffering disproportionate collapse. This performance objective may be further expanded in the case of buildings that form part of critical infrastructures (e.g. hospitals, power stations, passenger terminals), are occupied by a large number of people or are open to the public (e.g. schools, sports and commercial centres). In those situations, there is even the need for resilient buildings, which can be defined as buildings that are able to absorb and recover from an extreme event, maintaining operation and functionality, according to what is generally defined as physical resilience at the larger scale of urban infrastructure systems. Therefore, the resilience of a building includes not only the structural property of robustness, which contributes to the capacity of absorbing an extreme event, but also a recovery capacity that allows the pre-event performance level to be quickly restored or even improved.