Structural Performance for Multi-hazards Program

Summary

This program addresses the gap between basic research and building codes, standards, and practice through measurement science research to: (1) predict structural performance up to failure under extreme loading conditions: (2) assess and evaluate in-situ structural capacity using novel, smart sensing metrology and the ability of existing structures to withstand extreme loads; (3) design new buildings and retrofit existing buildings using cost-effective, performance-based methods; and (4) derive lessons learned from disasters and failures involving structures.  The program enhances the robustness of structures by focusing primarily on cross-cutting research topics including prevention of disproportionate collapse and disaster and failure studies, along with the specific hazards of extreme winds and coastal inundation.  This program also carries out statutory activities required for the implementation of the National Windstorm Impact Reduction Act (2004). The 2015 reauthorization of the National Windstorm Impact Reduction Program (Public Law, PL 114-52) directed NIST to perform as Program Lead Agency.

Description

Worker looks over the disaster site at New York City's World Trade Center complex a few days after the Sept. 11, 2001, terrorist attacks.

Credit: FEMA

Objective:
To develop and deploy advances in measurement science to enhance the robustness of buildings and infrastructure to natural and manmade hazards. 

What is the technical idea?

The fundamental new idea is that structural robustness can be significantly enhanced by developing reliable capabilities to predict the effects of hazards on the performance of buildings and infrastructure.  This will be achieved by developing: (1) measured data to characterize the hazard environment; (2) validated physics-based models to predict performance of structures to failure; (3) metrics, tools, and methodologies for measuring in-situ structural capacity and evaluating structural performance; (4) acceptance criteria for differing levels of performance objectives; and (5) mitigation strategies based on evaluated performance. The scope of this program encompasses structural performance under aging effects, extreme winds, including tornadoes, coastal inundation, mitigation of disproportionate collapse, and experimental structural research to advance the development of performance-based design standards. 

What is the research plan?

The program consists of three research thrusts:

(1) Develop validated tools that predict structural performance to failure under extreme loading conditions.  This research thrust consists of three elements:

• Develop an improved understanding of the hazards to the built environment.  The outcomes of this element will include:  innovative methods for defining design wind speeds and loads; risk-based storm surge maps; and improved understanding of disproportionate collapse of structures.
• Develop validated structural response models that characterize structural response from initial loading to failure for individual hazards (e.g., wind) and within a multi-hazard context.  The outcome of this element will be rational assessment of safety and reliability of structures at specified performance levels for individual hazards and within a multi-hazard context.
• Develop validated, simplified tools to characterize structural response from initial loading to failure for individual hazards and within a multi-hazard context.  The outcome of this element will be validated, simplified tools that can be used by practicing structural engineers in routine structural design.   

(2) Develop validated tools to assess and evaluate the capabilities of existing structures to withstand extreme loads.  This research thrust consists of three elements:

• Develop validated tools for use in initial visual evaluation and in simplified analyses.  The outcome of this element will be rapid visual screening methodologies and simplified analytical tools to evaluate the ability of existing structures to withstand extreme loads.
• Develop validated models for detailed analysis from initial loading to projected failure.  The outcome of this element will be experimentally validated, high-fidelity models of the behavior of existing structures in response to extreme loads, from initial loading through collapse.
• Develop validated, simplified models for routine analysis from initial loading to failure.  The outcome of this element will be validated, simplified tools that can be used by structural engineers in routine practice for analysis of the response of existing structures to extreme loads from initial loading through collapse.

(3) Develop performance-based guidelines for cost-effective design of new buildings and, where warranted, rehabilitation of existing buildings.  This research thrust consists of four elements:

• Develop acceptance criteria for different performance levels.  The outcome of this element will be published performance criteria for structures subjected to extreme loads and under disproportionate collapse.
• Develop performance-based design guidelines for new structures.  The outcome of this element will be published design guidelines for new structures to address individual hazards, multi-hazards, and disproportionate collapse.
• Develop cost-effective mitigation strategies for existing structures.  The outcome of this element will be published guidelines for mitigation strategies for existing structures to individual and multi-hazards and disproportionate collapse.
• Develop performance-based pre-standards for new and existing structures.  The outcome of this element will be to provide to standards bodies performance-based pre-standards to address individual and multi-hazards and disproportionate collapse.  

Major Accomplishments

Some recent accomplishments in the area of Disaster and Failure Studies include:

• Release of the Joplin and Moore tornado data repositories

A recent accomplishment in the area of Implementation of Joplin Tornado Recommendations:

• Code requiring tornado shelters be installed in new and existing schools for 2018 IBC and 2018 IEBC
• Successful passage of code change proposals requiring storm shelters in new and existing schools in tornado prone areas as part of NIST Joplin recommendation 7 (tornado shelters)
• NIST code change proposals to IBC and IEBC requiring storm shelters for new and existing schools in tornado prone areas successfully passed ICC code hearing in October 2015 and will be part of 2018 IBC and 2018 IEBC
• Held tornado hazard maps development methodology stakeholder workshop