Improving the resilience of buildings in extreme events: The challenge of corner columns
Funded by: BBVA Foundation
Present-day society has an ever-growing need for resilient buildings able to stand up to extreme events, for example, terrorist attacks, vehicle impact, explosions and fires, which often cause damage to columns and can lead to progressive collapse through a chain of failures. Since progressive collapse is usually accompanied by serious damage and human casualties, in recent years intense work has been done on improving the resilience of critical buildings such as hospitals, schools and other multi-storey public buildings that are normally occupied by large numbers of people. The most advanced of the present codes quantify a building’s resilience by considering, in isolation, the consequences of a series of critical column failures. Both the scientific community and the codes have focused on studying the consequences of internal column failures and have given little attention to failures in corner columns in spite of the fact that the loss of these columns involves a serious risk of progressive collapse. The aim of this project is thus to study how to approach the possible failure of a corner column and avoid it spreading to the rest of the building.
This challenge will be met by a novel method based on:
1) Causing the failure of a corner column in an actual building that will be specially built for this project.
2) Calibrating a numerical model based on the results of the previous experiment, followed by a wide-ranging parametric study.
The project’s biggest impact will be on the recommendations made for new building designs and for strengthening techniques for existing buildings, including the possible failure of both internal and corner columns. In this way it is hoped to cover one of the present gaps in the codes and in different scientific fields.
Progressive collapse and robustness of precast concrete building structures – PREBUST
Funded by: Spanish Ministry of Science, Innovation and Universities
Extreme events (i.e. terrorist attacks, vehicle impacts, explosions, etc.) often cause local damage to building structures, and this can be most serious when one or more columns fail, leading to the 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 derived from 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 now is on achieving resilient buildings that can remain operational after such an event, especially when they form part of critical infrastructures, have a large number of occupants, or are public buildings.
Precast concrete components are being increasingly used to build public and administrative buildings, and large infrastructures. The special features of these constructions, especially as regards the joints between the elements, make them particularly vulnerable to extreme events. Although great advances have been made in research on the progressive collapse of cast-in-place concrete and steel-composite structures, almost no work has been done to date on the progressive collapse of precast concrete structures.
The aim of this project is to improve the robustness of precast concrete structures in order to reduce the risk of progressive collapse, with the following specific goals:
1) Identify any alternative load paths that could appear after the failure of one or more columns.
2) Examine the application and reliability of the current standards and recommendations.
3) Consider the design and construction strategies required to obtain robust buildings.
4) Define simplified design and calculation methods.
To achieve these aims, we will use an ambitious method involving both numerical and experimental studies. The experimental part will involve tests on a full-scale building with a precast concrete structure, considering different column failure scenarios, while the numerical part will be based on the use of advanced models, validated by the experimental results, to form the basis for a subsequent broad parametric study.
The project is an answer to the Horizon 2020 Challenge “Secure Societies”, and is expected to have a great impact on, for example:
1) Making tools available to engineers and architects, standard makers, software developers and construction companies for the design and construction of resilient precast concrete structures.
2) Put Spain at the forefront of research on progressive collapse and extreme events.
3) Improve the safety levels of buildings.
4) Encourage Spanish companies to venture abroad to countries where the present codes and recommendations require buildings resistant to progressive collapse.
Endure – Fuse-based segmentation design: Avoiding failure propagation in building structures
Funded by: European Research Council (ERC Consolidator Grant 2020)
Extreme events often cause local-initial damage to the critical elements of building structures, followed by a cascade of further failures in the rest of the building; a phenomenon known as “progressive collapse”. Current design philosophies are based on giving buildings extensive continuity, so that when a critical element fails its load can be re-distributed among the rest of the structure. However, in certain situations (e.g. initial failure of several columns) this extensive continuity introduces undesirable effects and actually increases the risk of progressive collapse.
Segmenting a building into individual units connected only by means of fuses would avoid a failure in one zone propagating to others. While such fuses would provide continuity for normal loads or small local-initial failure, they would “isolate” the different parts of the building when otherwise the forces generated by the initial failure would pull down the rest of the structure. Although fuse segmentation is probably the only alternative that can fill the gaps in the present design philosophies, so far, no studies have been carried out on the possibility of applying it to buildings.
Endure’s overall aim is to develop a novel fuse-based segmentation design approach to limit or arrest the propagation of failures in building structures subjected to extreme events.
The project will be multidisciplinary and highly ambitious, and will achieve its overall aim by:
1) Developing a performance-based approach for the design of fuse-segmented buildings;
2) Designing, manufacturing and testing fuses for segmenting buildings; and
3) Implementing fuses in segmented realistic building prototypes and testing and validating the new fuse-based approach in these structures.
Endure will open up a new research area and design approach, and also deliver novel construction procedures. The project will lead to safer buildings, especially in the case of extreme events with severe consequences for building integrity.