SHDS · Seismic-resistant Highly Deformable Structures

Seismic-resistant Highly Deformable Structures

The earthquakes that have recently struck Europe, L’Aquila (2009), Lorca (2011) and Amatrice (2016) have shown that even for a moderate seismic hazard level the seismic action can cause huge personal and economic losses. Traditional force-based seismic resistant strategies rely on providing sufficient lateral strength and ductility for a structure to resist an earthquake. The strength of the structures depends on the hazard level at the site (ground accelerations) which can be significant, hence leading to the design of highly uneconomical structures. Existing codes, however, do allow reducing such large lateral forces in favour of more cost-effective structures, provided that the resulting structures can endure a certain amount of damage before collapse. This traditional design philosophy is straightforward, easy to use for practicing engineers, and can be effective at avoiding potential loss of life. However, force-based methods do not allow engineers to decide the way in which a structure can adapt to seismic actions and can lead to undesirable failures. Alternatively, the most advanced philosophies in seismic design target not only the prevention of casualties but also aim to design structures that can ”resist earthquakes of different severity within specified limiting levels of damage” (Performance Based Design -PBD). That would enable the development of optimal structures, maximise use of resources, minimise costs, yet yielding acceptable levels of safety, hence resulting in safer, more resilient and sustainable structures. Such a novel design methodology would also empower designers to experiment with new design solutions, innovative materials and structural components so as to achieve the desired performance levels. This action focuses on a very specific structural component: coupling beams in coupled wall systems. In this system two or more structural walls are linked through beams in regular pattern over the height of the structure. Coupling beams improve the seismic performance of each individual wall and provide a very stable source of energy dissipation. However, the overall behaviour of the system depends heavily on the deformation capacity of the coupling beams. In general, coupling beams are deep elements and their structural performance under seismic action is highly shear-dominated, with very limited deformation capacity. The main objective of SHDS is to develop innovative solutions for the construction of coupling beams with unparalleled deformation capacity so as to improve the performance of more traditional design solutions and guarantee higher level of safety and resilience. The coupling beams being developed in this action work as “fuses” and are the first elements to attract considerable damage during an earthquake, in turn protecting the majority of the remaining structural and non-structural components. Much of the deformation capacity of such innovative structural elements is made possible through the use of a newly developed Highly Deformable Concrete (HDC). HDC is a new material developed within the EU-funded project Anagennisi led by the University of Sheffield. Anagennisi aimed at finding ways of using all components of post-consumer tyres in high value concrete applications. One of the research lines in this project focused on replacing the mineral aggregates in concrete with rubber particles so as to increase the deformation capacity of traditionally brittle concrete. However, high deformability can only be achieved with high rubber content, which in turn can drastically reduce its compressive strength (up to 90%), thus making it unfit for structural use. The innovative HDC uses externally applied advanced composite jackets to enhance the compressive strength to structural grade while keeping the desired large axial deformation capacity of rubberised concrete. A mere 1.6mm thick Aramid jacket wrapped around rubberised concrete columns can lead to extraordinary strength and deformabi

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз