Daniel Medina

Daniel Medina

Future Researcher

Is the E.030 Standard Enough?

12 minute read

Published:

Introduction

On the morning of November 1, 1755, during All Saints' Day, a catastrophic event shook Lisbon. It was one of the most devastating earthquakes in modern history, classified as an XI intensity on the Mercalli scale (extreme earthquake). This disaster was not isolated; it was accompanied by a tsunami and a fire. Reports from the time indicate that the earthquake lasted between three and six minutes, causing cracks up to five meters wide in the city's center. Survivors who fled to the docks saw the water recede, revealing the seabed. Forty minutes later, three giant waves, ranging from 6 to 20 meters high, swept through the port and the city center, advancing up the Tagus River. In areas unaffected by the tsunami, fires erupted, devastating the city for five days, mostly ignited by candles lit in churches in honor of the deceased.

Epicenter and tsunami arrival time, Lisbon earthquake 1755.

Fig. 1 Epicenter and tsunami arrival time, Lisbon earthquake 1755. Source: "Wikipedia".

Of the 275,000 inhabitants of Lisbon, around 90,000 people died. In Morocco, another 10,000 people lost their lives, and in Ayamonte, Spain, more than 1,000 people perished. The earthquake left victims and damage throughout the Iberian Peninsula. However, this tragic event brought with it a unique opportunity: the chance to rebuild the city from scratch. Thanks to the efforts of the Marquis of Pombal, Sebastião José de Carvalho e Melo, the reconstruction of the Portuguese capital began. Together with engineers and architects, the first seismic-resistant designs were implemented, using city models placed on shaking tables to estimate the seismic response. Today, Lisbon is one of the most beautiful cities, bearing witness to the origin of seismology and seismic-resistant design.

Reference painting of the 1755 Lisbon earthquake.

Fig. 2 Reference painting of the 1755 Lisbon earthquake. Source: "Mega Curioso".

Over time, seismology became a defined scientific discipline. In the 19th and early 20th centuries, the first seismographs were developed, allowing precise measurements of seismic movements. In 1933, the Structural Engineers Association of California (SEAOC) was formed, dedicated to establishing criteria and methodologies for seismic-resistant design. Its goal was to ensure that buildings not only withstand seismic forces but also minimize human and material losses.

Peru is no stranger to this history. Its geographical location on the convergence zone of the Nazca and South American tectonic plates has led to numerous disasters, such as the Lima earthquake in 1746, Cusco in 1950, and Yungay in 1970. This history of disasters led to the creation of the E.030 Seismic-Resistant Design Technical Standard, which compiles all this historical experience and contextualizes it for Peru. But this raises many questions: Are the standards in the code still useful? Is this code sufficient for modern times? How long has the code been in effect? Will it be enough when the expected moment magnitude 8.8 earthquake occurs, as estimated by the IGP? This article seeks to answer these questions, including a final reflection from the author.

Evolution of the E.030 Standard

  • 1977: First Edition: This document established the basis for seismic-resistant design, including the use of equivalent lateral forces to represent seismic actions on structures. It also proposed ductility requirements for structural elements.

  • 1997: First Major Update: Response spectra for different soil types and seismic design levels were introduced. Criteria for performance-based design were established, focusing on the expected behavior of structures under different seismic levels. More specific detailing requirements for structural elements were included to ensure proper behavior during an earthquake.

  • 2003: Review and Improvement: Dynamic analysis methods were introduced, including modal spectral analysis and time-history analysis. Capacity design criteria were reinforced to ensure that structures have an adequate hierarchy of strength and ductility. Requirements for the design and anchorage of non-structural systems and equipment were included, recognizing their importance for seismic safety.

Evolution of seismic zoning map.

Fig. 3 Evolution of seismic zoning map. Source: "NORMA E.030 (2003, 2019)".

  • 2014: New Modification by Supreme Decree N° 002-2014-VIVIENDA: Seismic response spectra were updated based on recent studies and new seismic data. The country’s seismic zoning was revised, adjusting seismic coefficients according to new geotechnical and seismic information. Procedures for the evaluation and rehabilitation of existing structures were included, emphasizing the need for updating and reinforcing old buildings. Performance-based design criteria were strengthened, with clearer and more objective performance levels established for different types of structures.

  • 2016: Significant Update: This version introduced new approaches for seismic-resistant design and construction, improving safety standards. The importance of evaluating the non-linear behavior of structures was emphasized, although it was still primarily based on linear analysis methods.

  • 2019: Recent Modification by Ministerial Resolution N° 043-2019-VIVIENDA: Criteria for the use of advanced technologies such as seismic isolators were incorporated, specifying in which types of buildings these devices should be used. Design requirements for essential buildings, such as hospitals and fire stations, were increased to ensure their operability post-earthquake.

Evolution of International Standards

Globally, the main objective of building codes is to prevent buildings from causing massive loss of life during earthquakes. This "life safety" approach focuses on preventing structural collapse, although it does not necessarily minimize damage or loss of functionality in buildings. Current codes consider the concept of acceptable risk, establishing minimum standards that seek to balance the costs of seismic-resistant construction with the likelihood of unacceptable losses in future earthquakes. Even in high seismic risk areas, severe earthquakes are infrequent, leading to many buildings never experiencing severe seismic shaking during their approximate 50-year lifespan. Therefore, codes are developed considering this acceptable risk, ensuring life safety but allowing significant damage that may render buildings irreparable after a seismic event.

Options for seismic-resistant design

Fig. 4 Options for seismic-resistant design. Source: "(Fema, n.d.)".

For new buildings, codes specify two levels of seismic intensity for design: the maximum considered earthquake (MCE) and the design earthquake. The MCE aims to minimize the probability of structural collapse to prevent massive loss of life, while the design earthquake, with an intensity two-thirds of the MCE, seeks to limit damage that could injure occupants or prevent the functioning of essential services.

Historically, the objectives of the codes focused on different aspects, showing an evolution in this regard:

  • Prevention of Initial Collapse: The first codes focused solely on preventing the collapse of buildings during earthquakes. Engineers of the time did not have the knowledge or technology to achieve better performance.
  • Reduction of Anticipated Damage: As engineers gained confidence in their ability to minimize the risk of collapse, codes began to include criteria to reduce damage to non-structural systems and essential components such as hospitals.
  • Acceptance of Risk and Technological Development: With the evolution of knowledge and technology, codes adapted to include more advanced analysis methods and detailed specifications for the design of structural elements, non-structural systems, and equipment.
  • Shift Toward Recovery-Based Performance: Social dissatisfaction with acceptable levels of damage in current codes and the development of new tools to predict seismic performance have motivated a reconsideration of the life safety objective. In recent years, there has been a movement toward a resilience and functional recovery-based approach, seeking to ensure that buildings and critical infrastructure can be quickly restored after an earthquake, maintaining community viability.

Challenges of the E.030 Standard

  • Linear Analysis Methods: The E.030 standard, like many others worldwide, predominantly uses linear analysis methods for seismic-resistant design, although the actual behavior of structures during an earthquake is non-linear. This can result in an underestimation of seismic demands and an overestimation of the structures’ capacity to resist these events. Although the standard includes factors to estimate inelastic response, the probability of these cases occurring has not been adequately verified due to the lack of large-magnitude earthquakes during the standard’s validity period.

  • Response Spectra: The response spectra included in the standard do not always adequately reflect local seismic characteristics. The lack of adaptation of the spectra to local conditions can lead to suboptimal designs. Other countries already use sets of response spectra that vary depending on return period, zoning, and other factors.

  • Seismic Parameter Updates: The updating of seismic parameters, such as the maximum ground acceleration and seismic zoning factors, is not done with the necessary frequency. The lack of updated data can result in designs that do not reflect the current and future seismic conditions of the country.

  • Misuse of the Standard: Another important factor is that for the presentation of the Structural Project, the Peruvian Engineers Association (CIP) does not limit the participation of the Responsible Professional (PR), allowing any engineer without a specialty to apply the standard when it should require specialization, years of experience, and a fixed amount of research hours for the plan to have the validity to be executed in construction, which is the international standard.

Final Reflection

Throughout history, seismic-resistant design standards have evolved significantly, driven by catastrophic events such as the 1755 Lisbon earthquake and the numerous earthquakes throughout Peru. These standards have progressed from simple prevention of building collapse to the incorporation of advanced performance-based design criteria. However, despite these advances, there are inherent engineering uncertainties that cannot be completely eliminated. As engineers, it is common and necessary to make assumptions and simplifications in our designs. These decisions, though based on the available knowledge and technology, should be clearly communicated and made public. Decision-makers, responsible professionals, and the general community must understand the limitations and assumptions involved in seismic-resistant designs.

On the other hand, current technology provides us with advanced tools that allow us to automate and streamline design and analysis processes, reducing reliance on simplifying assumptions. Methods such as non-linear analysis and performance-based simulations offer a more accurate view of the behavior of structures during an earthquake, surpassing the limitations of traditional methods.

In the academic field, universities should not limit themselves to teaching the use and application of existing standards. Future engineers should be educated in the creation, evaluation, and critique of these normative documents. They must learn to go beyond what is established, exploring innovations and new technologies that can improve current standards. This critical and reflective approach will foster a culture of continuous improvement and adaptation in seismic-resistant engineering.

It is evident that standards seek to establish a minimum benchmark for safety and seismic-resistant design. However, this minimum standard should not limit or box in engineering practice. On the contrary, it should serve as a starting point for incorporating new technologies and innovative approaches that can offer a higher level of safety and resilience. Engineering must be a dynamic discipline, capable of evolving and adapting to the challenges and opportunities presented by the modern world.

Bibliography

  • Benazouz, C., Moussa, L., & Ali, Z. (2012). Ductility and inelastic deformation demands of structures. Structural Engineering and Mechanics, 42(5), 631-644.
  • Castaldo, P. (2014). Integrated seismic design of structure and control systems (pp. 1-220). New York: Springer International Publishing.
  • Castelli, F., Lentini, V., & Grasso, S. (2017). Recent developments for the seismic risk assessment. Bulletin of Earthquake Engineering, 15, 5093-5117.
  • Chandler, A. M., Lam, N. T. K., & Sheikh, M. N. (2002). Response spectrum predictions for potential near-field and far-field earthquakes affecting Hong Kong: soil sites. Soil Dynamics and Earthquake Engineering, 22(6), 419-440.
  • Fema. (n.d.). Earthquake-Resistant Design Concepts An Introduction to Seismic Provisions for New Buildings Second Edition. Retrieved July 7, 2024, from www.ATCouncil.org
  • Haselton, C., Deierleien, G., Bono, S., Ghannoum, W., Hachem, M., Malley, J., … & Cedillos, V. (2016). Guidelines on nonlinear dynamic analysis for performance-based seismic design of steel and concrete moment frames. In 2016 SEAOC Convention.
  • Işık, E. (2021). A comparative study on the structural performance of an RC building based on updated seismic design codes: Case of Turkey. Challenge, 7, 123-134.
  • Mondkar, D. P., & Powell, G. H. (1977). Finite element analysis of non‐linear static and dynamic response. International journal for numerical methods in engineering, 11(3), 499-520.
  • Pan, P., Ye, L., Shi, W., & Cao, H. (2012). Engineering practice of seismic isolation and energy dissipation structures in China. Science China Technological Sciences, 55, 3036-3046.
  • Wasti, S. T., & Ozcebe, G. (Eds.). (2006). Advances in earthquake engineering for urban risk reduction (Vol. 66). Dordrecht, Netherlands: Springer.
  • Zhang, C., Wu, C., Wang, P., Li, D., & Lu, J. (2024). Improved methods for synthesizing near-fault ground motions based on specific response spectrum. Soil Dynamics and Earthquake Engineering, 183, 108790.

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