Fernando Gutiérrez-Urzúa

Bio: Fernando Gutiérrez-Urzúa is an academic researcher from University College London. The author has contributed to research in topics: Masonry & Infill. The author has an hindex of 2, co-authored 6 publications receiving 12 citations.

Innovations in earthquake risk reduction for resilience: recent advances and challenges

Abstract: The Sendai Framework for Disaster Risk Reduction 2015-2030 (SFDRR) highlights the importance of scientific research, supporting the ‘availability and application of science and technology to decision making’ in disaster risk reduction (DRR). Science and technology can play a crucial role in the world’s ability to reduce casualties, physical damage, and interruption to critical infrastructure due to natural hazards and their complex interactions. The SFDRR encourages better access to technological innovations combined with increased DRR investments in developing cost-effective approaches and tackling global challenges. To this aim, it is essential to link multi- and interdisciplinary research and technological innovations with policy and engineering/DRR practice. To share knowledge and promote discussion on recent advances, challenges, and future directions on ‘Innovations in Earthquake Risk Reduction for Resilience’, a group of experts from academia and industry met in London, UK, in July 2019. The workshop focused on both cutting-edge ‘soft’ (e.g., novel modelling methods/frameworks, early warning systems, disaster financing and parametric insurance) and ‘hard’ (e.g., novel structural systems/devices for new structures and retrofitting of existing structures, sensors) risk-reduction strategies for the enhancement of structural and infrastructural earthquake safety and resilience. The workshop highlighted emerging trends and lessons from recent earthquake events and pinpointed critical issues for future research and policy interventions. This paper summarises some of the key aspects identified and discussed during the workshop to inform other researchers worldwide and extend the conversation to a broader audience, with the ultimate aim of driving change in how seismic risk is quantified and mitigated.

Influence of the design objectives on the seismic performance of steel moment resisting frames retrofitted with buckling restrained braces

Abstract: Buckling restrained braces (BRBs) represent an effective strategy for the seismic retrofit of existing steel moment resisting frames (MRFs), as they contribute to increasing the strength and ductility capacity of the structure. However, current design strategies do not provide recommendations on how the performance increase is achieved. Prioritising either the increase of strength or ductility capacity has an impact on the damage evolution and affects the overall performance of the structure. A low increase of strength typically requires larger exploitation of the ductility capacity (i.e., damage) of the existing structure, while a high increase of strength produces a significant increase of stiffness, which is often accompanied by an increase of the seismic demands that may limit the effectiveness of the retrofitting solution. The present study assesses the impact of these decisions on the overall performance of steel MRFs retrofitted with BRBs. For this purpose, two MRFs with several BRB retrofitting configurations are used as case study structures. Finite Element Models are built in OpenSees and assessed through Incremental Dynamic Analyses to account for the record‐to‐record variability. Fragility relationships are derived based on local Engineering Demand Parameters (EDPs) to describe structural and non‐structural damage, as well as path‐dependent damage indicators (i.e., residual drifts and cumulative ductility in BRBs). A comparison of the overall performance of the structures is carried out in terms of risk estimates for a high seismicity location.

The critical infrastructure

Abstract: This article gives an overview of a report issued by the President's Commission on Critical Infrastructure Protection (PCCIP). The primary focus of the commission's activity involved the investigation of the security of national and international information infrastructures.

On-going challenges in physics-based ground motion prediction and insights from the 2010-2011 Canterbury and 2016 Kaikoura, New Zealand earthquakes

Abstract: This paper presents on-going challenges in the present paradigm shift of earthquake-induced ground motion prediction from empirical to physics-based simulation methods. The 2010–2011 Canterbury and 2016 Kaikoura, New Zealand earthquakes are used to illustrate the predictive potential of the different methods. On-going efforts in simulation validation and theoretical developments are then presented, as well as the demands associated with the need for explicit consideration of modelling uncertainties. Finally, discussion is also given to the tools and databases needed for the efficient utilisation of simulated ground motions both in specific engineering projects as well as for near-real-time impact assessment.

A Simulation‐Based Framework for Earthquake Risk‐Informed and People‐Centered Decision Making on Future Urban Planning

Abstract: Numerous approaches to earthquake risk modeling and quantification have already been proposed in the literature and/or are well established in practice. However, most of these procedures are designed to focus on risk in the context of current static exposure and vulnerability, and are therefore limited in their ability to support decisions related to the future, as yet partially unbuilt, urban landscape. We propose an end-to-end risk modeling framework that explicitly addresses this specific challenge. The framework is designed to consider the earthquake (ground-shaking) risks of tomorrow's urban environment, using a simulation-based approach to rigorously capture the uncertainties inherent in future projections of exposure as well as physical and social vulnerability. The framework also advances the state-of-practice in future disaster risk modeling by additionally: (a) providing a harmonized methodology for integrating physical and social impacts of disasters that facilitates flexible characterization of risk metrics beyond physical damage/asset losses; and (b) incorporating a participatory, people-centered approach to risk-informed decision making. The framework is showcased using the physical and social environment of an expanding synthetic city. This example application demonstrates how the framework may be used to make policy decisions related to future urban areas, based on multiple, uncertain risk drivers.

Device uncertainty propagation in low-ductility RC frames retrofitted with BRBs for seismic risk mitigation

Abstract: Correspondence FabioFreddi,Department ofCivil, Environmental&GeomaticEngineering,UniversityCollegeLondon, London,UK. Email: f.freddi@ucl.ac.uk Abstract Passive control systems, such as buckling-restrained braces (BRBs), have emerged as efficient tools for seismic response control of new and existing structures by imparting strength and stiffness to buildings, while providing additional high and stable energy dissipation capacity. Systems equipped with BRBs have been widely investigated in literature; however, only a deterministic description of the BRBs’ properties is typically considered. These properties are provided by the manufacturer and are successively validated by qualification control tests according to code-based tolerance limits. Therefore, the device properties introduced within the structure could differ from their nominal design estimates, potentially leading to an undesired seismic performance. This study proposes a probabilistic assessment framework to evaluate the influence of BRBs’ uncertainty on the seismic response of a retrofitted RC frame. For the case study, a benchmark three-story RC moment-resisting frame is considered where BRBs’ uncertainty is defined compatible to the standardized tolerance limits of devices’ quality control tests. This uncertainty is implemented through a two-level factorial design strategy and Latin hypercube sampling technique. Cloud analysis and probabilistic seismic demand models are used to develop fragility functions for the bare and retrofitted frame for four damage states while also accounting for the uncertainty in the property of BRBs. Risk estimates are successively evaluated for three case study regions. The results show that, for the considered case study structure, these uncertainties could lead to an increase of fragility up to 21% and a variation in seismic risk estimates up to 56%.