What happens if a big earthquake hits Spain? It is probable that a lot of buildings built before 1974 (the year in which the seismic regulation PDS-74 was passed, obligating all architects to prepare buildings against earthquakes) and even some buildings built after this year, will collapse. That is, they would not survive the earthquake or they would suffer such damage that they would have to be completely demolished. A study by Professor Amadeo Benavent Climent, of the Department of Structural Mechanics and Hydraulic Engineering of the University of Granada, has designed a new “damage model ” to determine the earthquake resistance of these buildings, i.e. the energy that they could absorb and dissipate without collapsing.
This new “damage model ” designed by the researcher at the University of Granada improves the model of Park and Ang, which are two world authorities in this field, whose model was applied first to reinforced-concrete and then to steel structures. The main novelty of this model is that the proximity to the break in the structural component does not necessarily depend on the maximum deformation and the total energy dissipated, as in the model of Parks and Ang, but rather how this energy is consumed.
The results of this research have been published recently in the journal Earthquake Engineering and Structural Dynamics, one of the most important publications in the field of earthquake engineering. The great interest of the model designed by Benvent Climent lies in the fact that it can be applied to steel energy dissipaters, which are special devices also known as “seismic fuses”. These are devices installed in concrete or steel structures to avoid major damage of pillars and beams in the case of an earthquake. This new system would enable the reinforcement of the structure of buildings constructed before 1974, where the design did not take seismicity into account, and of those built between 1974 and 1994, for which seismic regulations did not require ductility.
The key is ductility
The UGR Professor states that the energy that a building absorb and dissipate depends largely on its ductility–that is, on the ability of its components to deform in a plastic way before breaking. According to Mr Benavent, “The first regulation obligating the use ductile solutions in construction was in 1994. When we speak of solutions, we refer not only to ductile materials, but also to the ductility of their arrangement”.
The use of energy dissipaters is very widespread in Japan, the United States, and some European countries. However, these devices are not very widely used in Spain. Mr Benavent points out that since it is not a very expensive system and it is highly efficient to protect buildings against earthquakes, the future of architectural structures will inevitably adopt them. This is why this system developed at the UGR is so important.
Reference: Amadeo Benavent Climent. Department of Mecchanics of Structures and Hydraulic Engineering of the University of Granada. Telephone Number: 958 246 109 – 958 249 960. E-mail Address: benavent@ugr.es
