Arresting failure propagation in buildings through collapse isolation.

Several catastrophic building collapses1-5 occur because of the propagation of local-initial failures6,7. Current design methods attempt to completely prevent collapse after initial failures by improving connectivity between building components. These measures ensure that the loads supported by the failed components are redistributed to the rest of the structural system8,9. However, increased connectivity can contribute to collapsing elements pulling down parts of a building that would otherwise be unaffected10. This risk is particularly important when large initial failures occur, as tends to be the case in the most disastrous collapses6. Here we present an original design approach to arrest collapse propagation after major initial failures. When a collapse initiates, the approach ensures that specific elements fail before the failure of the most critical components for global stability. The structural system thus separates into different parts and isolates collapse when its propagation would otherwise be inevitable. The effectiveness of the approach is proved through unique experimental tests on a purposely built full-scale building. We also demonstrate that large initial failures would lead to total collapse of the test building if increased connectivity was implemented as recommended by present guidelines. Our proposed approach enables incorporating a last line of defence for more resilient buildings.

Falls from height during the floor slab formwork of buildings: current situation in Spain.

PROBLEM: One of the phases with the highest risk of falls from a height in the construction of a building is during the floor slab formwork stage. This paper analyzes this particular risk, as well as the most frequently used fall-protection systems. METHOD: A survey was carried out to define the current situation in Spain with regard to falls from a height during floor slab formwork and the fall-protection systems used to prevent such a risk. RESULTS: The results of the survey clarified the current situation in Spain with regard to this risk, and made it clear that there is considerable risk of falling from a height during the floor slab formwork stage. DISCUSSION: All the safety systems analyzed presented a series of weak points that should be studied in detail before they can be used on building sites. IMPACT ON INDUSTRY: The risk of falling associated with floor slab formwork and the most frequently used protection systems are analyzed. As no research had been carried out to date on this type of risk, we consider the research presented in this article to be a pioneer in the field.