The advent of high-performance computers in architecture and construction has made it possible to perform calculations that, in the past, would have been practically impossible. This is the case for the calculation and design of structures for earthquake-prone areas. The application of these powerful computers to the performance of these calculations speeds up the process, makes it more accurate and facilitates the exploration of alternatives. But how are structures in buildings and bridges calculated to withstand the effects of earthquakes?
The first step in designing an earthquake-resistant structure is to decide what level of energy it should be able to withstand. In other words, the design must represent a balance between two extremes: that of the exorbitant expenditure required to withstand infinite seismic action, and the inadequacy of its strength, or its certain destruction, under the effect of small earth tremors. Logically, the design criteria will not be the same for a hospital as for a robotic warehouse.
Therefore, we arrive at the concept of performance design, a design that is established according to the desired behaviour of the structure in an earthquake. For example, a highly flexible structure will remain standing during an earthquake, but the non-structural elements will be severely damaged; as a result, the building will be unusable even though it has not collapsed. It may not be overly important that a house loses certain functionalities, as long as it does not collapse on the residents; however, functionalities are critical in a hospital, which must remain operational after an earthquake, when its services are most needed.
Precisely, the high computational power of computers allows us to model buildings in three dimensions and to simulate their movements during an earthquake with high accuracy. With such models we are able to identify the most vulnerable points, the most deformable points and the potential level of collapse of the building. As a result, structural engineering can strategically decide which parts of the structure to reinforce, or where to allow controlled deformations, in order for the building to meet the functional requirements in different seismic scenarios.
Structural engineering teams therefore optimise economic resources, which they invest in key areas to improve the habitability and safety of buildings in the event of earthquakes. In doing so, they not only protect structures, but also prioritise their ability to serve people at critical times.
By Jorge Laguna, head of the structures section of Amusement Logic’s Architecture Dept.
