Michel Bruneau

A Framework to Quantitatively Assess and Enhance the Seismic Resilience of Communities

This paper presents a conceptual framework to define seismic resilience of communities and quantitative measures of resilience that can be useful for a coordinated research effort focusing on enhancing this resilience. This framework relies on the complementary measures of resilience: “Reduced failure probabilities,” “Reduced consequences from failures,” and “Reduced time to recovery.” The framework also includes quantitative measures of the “ends” of robustness and rapidity, and the “means” of resourcefulness and redundancy, and integrates those measures into the four dimensions of community resilience—technical, organizational, social, and economic—all of which can be used to quantify measures of resilience for various types of physical and organizational systems. Systems diagrams then establish the tasks required to achieve these objectives. This framework can be useful in future research to determine the resiliency of different units of analysis and systems, and to develop resiliency targets and detailed analytical procedures to generate these values.

Seismic resilience of a hospital system

This paper presents a comprehensive model to quantify disaster resilience of systems that is defined as the capability to sustain functionality and recover from losses generated by extreme events. The model combines loss estimation and recovery models and can be applied to critical facilities (e.g. hospitals, military buildings, etc.), as well as utility lifelines (e.g. electric power systems, transportation networks, water systems etc.) that are crucial to the response of recovery processes, decisions and policies. Current research trend leads toward the definition of complex recovery models that are able to describe the process over time and the spatial definition of recovery (e.g. meta-models for the case of health care facilities). The model has been applied to a network of hospitals in Memphis, Tennessee. The resilience framework can be used as a decision support tool to increase the resilience index of systems, such as health care facilities, and reduce disaster vulnerability and consequences.

Exploring the concept of seismic resilience for acute care facilities

This paper explores the operational and physical resilience of acute care facilities, recognizing that the key dimension of acute care facilities is not a simple engineering unit. Quantification of resilience is first approached from the broader societal context, from which the engineering subproblem is formulated, recognizing that, to operate, hospitals depend intricately on the performance of their physical infrastructure (from the integrity of structural systems and nonstructural systems, lifelines, components, and equipment). Quantification relates the probability of exceeding floor accelerations and interstory drifts within a specified limit space, for the structural and nonstructural performance. Linear and nonlinear structural responses are considered, as well as the impact of retrofit or repair. Impact on time to recovery is considered in all cases. The proposed framework makes it possible to relate probability functions, fragilities, and resilience in a single integrated approach, and to further develop general tools to quantify resilience for sociopolitical-engineering decisions.

Building damage from the Marmara, Turkey earthquake of August 17, 1999

The objective of this paper is to provide a brief overview of damage as observed immediately following the earthquake. Detailed studies of structural seismic performance, conducted in the time elapsed since August 1999, are not the subject of this paper, but rather the object of other papers presented in this Special Issue of the Journal. Damage to reinforced concrete, masonry, and steel structures, is described. The mode the failure presented include: foundation failures; soft stories; strong beams and weak columns; lack of column confinement and poor detailing practice; buckling and fractures of steel members; and non-structural damage. Some general lessons learned from this earthquake are also formulated.

Resilience-Based Design of Natural Gas Distribution Networks

The concept of disaster resilience has received considerable attention in recent years and is increasingly used as an approach for understanding the dynamic response to natural disasters. In this paper, a new performance index measuring the functionality of a gas distribution network has been proposed, which includes the restoration phase to evaluate the resilience index of the entire network. The index can also be used for any type of natural or artificial hazard, which might lead to the disruption of the system. The gas distribution network of the municipalities of Introdacqua and Sulmona, two small towns in the center of Italy that were affected by the 2009 earthquake, has been used as a case study. The pipeline network covers an area of 136 km2, with three metering pressure reduction (M/R) stations and 16 regulation groups. Different analyses simulating different breakage scenario events due to an earthquake have been considered. The numerical results showed that the functionality of the medium-pressure gas distribution network is crucial for ensuring an acceptable delivery service during the post earthquake response. Furthermore,the best retrofit strategy to improve the resilience index of the entire network should include emergency shutoff valves along the steel pipes.

Seismic retrofit of flexible steel frames using thin infill panels

Non-linear inelastic analyses are conducted to investigate how structural behavior is affected when thin infills of steel, low yield steel, or Shearfill fabric are used to seismically retrofit steel frames located in regions of low and high seismicity, namely New York City and Memphis. A typical three-bay frame extracted from an actual 20-story hospital building in New York City is considered for this purpose. Fully rigid and perfectly flexible frame connection rigidities are considered to capture the extremes of frame behavior. It is found that the use of even very thin steel infill panels can significantly reduce story drifts without significant increases in floor accelerations, and that low yield steel behaves slightly better than standard constructional grade steel under extreme seismic conditions but at the cost of some extra material. It is also concluded that Shearfill membranes may not have the necessary strength and stiffness to be an effective retrofit solution, unless a thick membrane having multiple layers can be constructed.

Performance of steel bridges during the 1995 Hyogoken-Nanbu (Kobe, Japan) earthquake—a North American perspective

Abstract A large number of steel bridges were damaged by the January 17, 1995, Hyogoken–Nanbu (Kobe, Japan) earthquake. This damage is particularly relevant to Eastern North America where considerably more steel bridges exist than in Western North America where bridges exposed to past earthquakes were mostly of reinforced concrete. Therefore, in light of the Kobe earthquake, a comparison of the steel design practice and design requirements in Japan and North America is instructive. In this paper, such a comparison is first presented, followed by a review of the observed damage to steel bridges and a review of the causes for this damage. Then, the relevance of these observations to North American bridge design practice is examined.

Finite-Element Investigation and Design Recommendations for Perforated Steel Plate Shear Walls

This paper presents results from an investigation of the behavior of unstiffened thin steel plate shear wall (SPSW) having a regular pattern of openings (a.k.a. perforated SPSW). Finite element monotonic pushover analyses were conducted, first on a series of individual perforated strips with variation in perforation diameter, to develop a fundamental understanding of the behavior of complete perforated SPSW, then on a corresponding series of complete perforated SPSW having various perforation diameters. Three different sets of wall boundary conditions are considered, namely: flexible beam laterally braced, rigid floor, and rigid beam. Though some differences between the SPSW panel strips and the individual strip results are observed at large monitored strain, at lower monitored strain however the two models are in a good agreement. Based on the analytical results design recommendations of these perforated SPSWs are presented. The shear strength of a SPSW infill plate having a pattern of multiple regularly spaced circular perforations can be calculated as a function of the shear strength of a solid panel, perforation diameter, and distance between perforations.

Capacity Design of Intermediate Horizontal Boundary Elements of Steel Plate Shear Walls

Consistent with capacity design principles and requirements of ductile behavior, the 2005 AISC and 2001 CSA seismic design codes require that the intermediate horizontal boundary elements HBEs of steel plate shear walls SPSWs be designed to remain essentially elastic with the exception of plastic hinges at their ends when the infill plates fully yield under seismic loading. However, the unexpected failure observed during the tests on a full-scale two-story SPSW suggested that the current design approach does not necessarily lead to an intermediate HBE with the expected performance. This paper presents analytical models for estimating the design forces for intermediate HBEs to reliably achieve capacity design. Those models combine the assumed plastic mechanism with a linear beam model of intermediate HBE considering fully yielded infill panels and are able to prevent in-span plastic hinges. Design forces predicted using the proposed models are compared with those from nonlinear finite element analysis. Good agreement is observed. Finally, the proposed models are also used to explain the observed premature failure of intermediate HBE. DOI: 10.1061/ASCEST.1943-541X.0000167 CE Database subject headings: Shear walls; Steel plates; Earthquake engineering; Seismic design. Author keywords: Shear walls; Steel plates; Capacity; Design; Earthquake engineering; Seismic design.

Seismic performance of multispan simply supported slab-on-girder steel highway bridges

Abstract The seismic response of existing multispan simply supported slab-on-girder steel highway bridges, never designed to resist earthquakes, is studied. Elastic response spectrum analyses are conducted for bridges with different bearing stiffness, span length and number of spans. It is found that the response of two-span simply supported bridges is highly dependent on the stiffness of fixed bearings on the abutments, but this effect vanishes as the number of spans increases. The transverse direction seismic capacity of bridges having more than two spans is not a function of the number of spans. These bridges may be damaged by earthquakes having peak accelerations less than 0.20 g. However, bridges with identical end-to-end length but subdivided into a smaller number of spans are found to be more vulnerable to seismic excitations than those with larger number of spans. Increasing span length is also found to have a negative impact on the seismic capacity of these bridges. Additionally, analytical expressions to calculate the minimum required seat width are developed.