Elena Oliver Saiz: "Less than 25% of constructions in Venezuela comply with seismic standards"

London / BarcelonaElena Oliver Saiz is a lecturer at the Universitat Politècnica de Catalunya and a specialist in seismic engineering. A PhD from the University of Granada, she has researched nonlinear simulation, finite elements, and energy dissipation, with complementary stays at Berkeley. She has worked as a project manager on large international projects and currently focuses her research on the seismic behavior of tall buildings with energy dissipation systems.

In this interview, she provides a technical perspective on how, from architecture and construction techniques, the worst consequences of earthquakes, such as the one in Venezuela, can be foreseen.

To what extent are Venezuelan buildings and infrastructure prepared to withstand earthquakes of magnitude greater than 7 on the Richter scale?

— In the regulatory field, a more detailed study of the accelerations recorded in each case would be necessary to determine if they correspond to what is provided for in the regulations according to the situation, although they can possibly be related to the higher levels foreseen by recent Venezuelan regulations for some of the affected areas. However, the biggest problem has to do with the lack of effective application and the existence of informal self-built construction. To this should be added the construction that may have been undersized because it was built prior to the most recent regulations.

What characteristics of Caracas' urban planning and real estate stock make the city particularly vulnerable to a major earthquake?

— The biggest problem is informal self-built buildings, where the quality of construction is very poor. Furthermore, their vulnerability can be aggravated by rugged topography or the nature of the terrain.

What measures should Venezuelan authorities prioritize to reduce damage and loss of life in future major earthquakes?

— A structural reinforcement program could be implemented that prioritizes critical infrastructures, such as hospitals and schools, but also requires certain measures to be taken for residential buildings. Furthermore, it would be essential to improve the appropriate technical review mechanisms that mandate the effective application of existing regulations.

What are the main differences between Venezuela's seismic regulations and those of countries like Japan or Chile?

— Among these countries there are critical differences related to normative development over time, but also to their effective application. Chile was a pioneer in South America in implementing its first code in 1935. On the other hand, Venezuela was also among the first to adopt its first regulation in 1939, and had a key turning point after the 1967 Caracas earthquake, which acted as a catalyst for a thorough revision of the regulations. For its part, Japan is distinguished by its technical avant-garde, as it allows for much more refined approaches that go far beyond the force-based approach more common in other regulations. However, the level of compliance and effective application is the greatest divergence: while in Chile it is estimated that regulations are applied in more than 75% of buildings, in Venezuela the compliance with regulations is calculated at less than 25% of constructions. As a consequence, the increase in informal construction in Venezuela has generated a large number of housing units that fall outside regulatory control.

What types of buildings or infrastructures are most at risk of collapse in an earthquake of this magnitude?

— Besides informal self-built neighborhoods, practically without structural capacity to withstand these types of events, among the rest of the more or less formal built environment there are usually design problems that are well known in the field of seismic engineering. Among these problems, the existence of ground floors with less resistance than the upper floors stands out, the presence of short columns (usually due to the annexation of a wall that has not been considered as a structural element, but which restricts its lateral deformation capacity) or the strong beam and weak column condition. All these design errors cause poor structural behavior, as they can lead to brittle failure.

Is it possible to reinforce old buildings to meet modern seismic standards, or is it often more viable to replace them?

— Completely and, often, it is much more economically viable to reinforce them. Modern techniques, such as the use of metal heat sinks or jacketing with fiber-reinforced polymers, allow for improved strength and ductility. These advanced techniques are already highly developed and can be implemented relatively simply.

But is it done habitually?

— One of the main problems is that seismic-resistant regulations have evolved rapidly in many countries, at a much faster rate than the renovation of the existing building stock. For example, in the European Union, 80% of the built stock predates the nineties and 40% predates the sixties, periods in which seismic regulations were non-existent or very rudimentary. This has caused many buildings to be clearly undersized with respect to current standards. In our country, although buildings must undergo periodic mandatory technical inspections, these sometimes focus on the visible state of the structure under gravitational actions, without directly addressing the need for an update for seismic loads following current criteria.