Disaster resilience of a building or a community is the capability to quickly restore full functionality following an extreme event. Buildings play a critical role in achieving community resilience because of their importance in providing emergency response, essential services, and shelter, and because of the significant economic costs and potential loss of life associated with building damage or collapse. This project will develop the measurement science to assess the disaster resilience of buildings through the use of risk-based assessment and decision methods that are supported by a cost/benefit analysis and performance-based design and rehabilitation methodologies. A key component of a resilient building is a robust structural system, which limits the spread of collapse when subjected to extreme natural and man-made hazards. Many U.S. buildings are vulnerable to partial or total collapse under abnormal loads not considered in building design. At present, there is no accepted engineering methodology to assess and enhance overall structural robustness within a multi-hazard context that considers both design loads and abnormal loads. This project will address the development of procedures and computational methodologies for assessing overall structural robustness and will provide the measurement science needs for the development of performance-based provisions in U.S. codes and standards for disproportionate collapse resistance that will enhance the disaster-resilience of buildings.
Objective: By FY 2014, develop the measurement science to assess the disaster resilience of buildings through the use of risk-based assessment and decision methods, and develop performance-based pre-standards for mitigation of disproportionate collapse of steel and reinforced concrete structures.
What is the new technical idea? Disaster resilience is the capability of a system and its components—such as a community and its buildings and infrastructure—to quickly recover full functionality following an extreme event. Since buildings play a critical role in achieving community resilience, this project will initially focus on developing the measurement science to assess building resilience. This research project seeks to develop performance-based design methodologies for buildings subjected to a wide variety of natural and man-made hazards, and to provide a framework for other hazard-based projects, including earthquake, windstorm, and fire hazards.
The new technical idea is to develop the tools to measure the disaster resilience of buildings using risk-based assessment and decision methods that are supported by a cost/benefit analysis and performance-based design and rehabilitation methodologies. The tools will consider, for a wide spectrum of hazards, a holistic approach to building resilience that includes performance of structural and nonstructural building systems, system damage and loss of functionality following the event, the duration of recovery, and associated economic losses. Of particular interest is the need to develop appropriate design events/scenarios and performance goals and measures for resilience that account for life safety, building usability/functionality during and after an event, and the time and costs required to resume service. Performance criteria and metrics for building resilience will enable the development of decision tools for planners and stakeholders to enhance the performance of buildings during and after extreme events, thus reducing loss of life, injuries, and economic losses. This project will develop (1) performance criteria and metrics for evaluating building resilience, (2) design and retrofit strategies for resilience, and (3) risk-based assessment and decision methods for achieving building resilience that are supported by a cost/benefit analysis and performance-based methods for codes, standards, and practices.
A key component of a resilient building is a robust structural system, which limits the spread of collapse under extreme natural and man-made hazards. Therefore, an important focus of the project is to develop system-level performance metrics for robustness of building structures. Robustness is a key structural property that is related to disproportionate collapse resistance. Both structural redundancy and integrity are key factors that influence the robustness of the structure. The combined influence of these factors must be quantified to express the robustness in a meaningful and measurable manner. The assessment of structural robustness requires simulation of structural behavior under various local failure scenarios. Realistic and efficient simulations require the development and use of advanced and experimentally validated modeling methodologies to examine the structural system performance. Both traditional and new design concepts will be evaluated to determine the relative merits of various structural systems in resisting disproportionate collapse. The project will examine collapse limit states of various structural systems to quantify their reserve capacities, through a combination of push-down and push-over analyses. Reserve capacity measures will support resilience metrics for system damage. The project will also develop design and retrofit methodologies that take explicit advantage of the synergies associated with mitigating disproportionate collapse under multiple hazards to enhance overall structural performance, efficiency, and cost-effectiveness.
What is the research plan? NIST, through its Disaster Resilience of Buildings, Infrastructure, and Communities goal, is developing the measurement science to assess the performance of structures exposed to earthquake, tsunami, hurricane winds and storm surge, tornados, wind- and water-borne debris, and fire hazards. These efforts have the goal of providing the technical basis for performance-based approaches for the design of new buildings and the rehabilitation of existing buildings for these hazards. This project is cross-cutting with all programs in the Disaster Resilience of Buildings, Infrastructure, and Communities goal and will work closely with NEHRP, NWIRP, and Fire Research Division teams to develop consistent performance criteria and metrics for building resilience.
The proposed approach will be to develop resilience performance criteria and metrics that account for building performance under multiple hazards, including the performance of structural and nonstructural building systems during a hazard event, system damage and loss of functionality following the event, the duration of recovery, and associated economic losses. The primary focus will be the performance of structural and non-structural building systems (e.g., architectural, mechanical, and life safety systems), utility infrastructure housed within or below the building (such as water, wastewater, gas, power, and communications), adjacent transportation facilities (e.g., subway, roads, etc.), and adjacent buildings or facilities. To develop resilience metrics, the project will use data from past events, engineering judgment, and engineering analyses to evaluate the performance of building systems. The project will consider scenario-based events (events that exceed typical design requirements), including a variety of natural and manmade hazards, as candidates for evaluating building resilience. In addition, the project will provide a technical basis for cost/benefit analysis of design or rehabilitation approaches to enhance the resilience of buildings. In 2011, a DHS-NIST sponsored workshop, organized with ANSI-HSSP, was held to identify gaps in our current codes, standards, and practices related to resilience and to identify candidate metrics for resilience. A roadmap for NIST research in building and community resilience is being formulated based on input from this workshop.
This project will conduct a comprehensive comparison and assessment of current structural design provisions in standards and codes, including loads and material-specific (steel and reinforced concrete) design. The comparison will include current U.S.-based codes and standards including the International Building Code, ASCE standards, ACI standards, and AISC standards, as well as international codes and standards including ISO standards, the Eurocode, and codes and standards from Japan, New Zealand, Australia, etc. The code comparison and assessment will include steel and reinforced concrete structures and will address the following loads or hazards: (1) fire, (2) wind, (3) earthquake, and (4) coastal flooding (storm surge and tsunami), along with their combinations in a multi-hazard context. The comparison and assessment will have the following objectives: (1) identify differences between codes and standards for the U.S. and other countries/regions, (2) identify gaps in codes and standards and associated research needs, and (3) use the results from (1) and (2) to drive changes to improve U.S. or ISO standards. In addition, test cases (or case studies) of design loads for selected types of construction (e.g., low, medium, and high rise) will be evaluated for various codes and standards to quantify differences in design requirements, including magnitude, mean recurrence intervals (MRI), and associated risk (probability of failure) levels where appropriate. In FY 13, this task will focus on fire loads and effects on structures.
A case study analysis using HAZUS MH will vary the magnitude of the hazard and analyze the losses associated with different levels of hazard mitigation, as reflected in selected building codes. The case study findings will be used to demonstrate how to apply cost/benefit analysis to promote more cost-effective design/rehabilitation approaches.
Because resistance to disproportionate structural collapse is crucial for achieving building resilience, this project also addresses the measurement of structural robustness. The recommendations from a national workshop formed the basis for a coordinated national plan for problem-focused research on mitigation of disproportionate collapse of buildings. The project proposes to develop metrics to quantify the robustness of various structural systems to assess their disproportionate collapse potential. These metrics will be based on experimentally validated computational models of structural systems incorporating the predominant behaviors and failure modes of components and connections. Such models can also be used by design professionals in design for disproportionate collapse resistance. A key component in the development and evaluation of robustness metrics will be a series of push-down and push-over analyses to assess the reserve capacity of a variety of structures with different systems and materials. The project will develop performance objectives, acceptance criteria, and evaluation methods for both new and existing structures, which will be used to develop guidance documents and pre-standards for design and rehabilitation of structures to mitigate disproportionate collapse. The work on building resilience will produce the following outcomes in the near term:
The work on structural robustness will produce the following outcomes:
Outputs, Building Resilience:
Outputs, Structural Robustness:
Outcomes, Building Resilience:
Outcomes, Structural Robustness:
Standards and Codes:
Start Date:November 3, 2011
Lead Organizational Unit:el
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