Papers by Therese McAllister
A high-level review was conducted of design criteria in the United States for major components of... more A high-level review was conducted of design criteria in the United States for major components of the built environment for selected design and construction codes, reference standards, and best practices. The intent of the review is to gauge the expected performance of current building and infrastructure design from a community resilience perspective for natural hazard events. Design criteria that support community resilience were evaluated, including design hazard characterization, expected performance, recovery of function, interdependency issues, and emerging methods. The impact of changing environmental conditions on infrastructure design and performance was also examined, and areas needing improvement are identified. The review focused on design criteria related to flood, wind, and seismic hazards. Likewise, the systems of the built environment reviewed include buildings, water and wastewater systems, electrical power systems, and transportation systems. Although community resi...
Journal of Structural Engineering, 2022
The retrofit of wood-frame residential buildings is a relatively effective strategy to mitigate d... more The retrofit of wood-frame residential buildings is a relatively effective strategy to mitigate damage caused by windstorms. However, little is known about the effect of modifying building performance for intense events such as a tornado and the subsequent social and economic impacts that result at the community level following an event. This paper presents a method that enables a community to select residential building performance levels representative of either retrofitting or adopting a new design code that computes target community metrics for the effects on the economy and population. Although not a full risk analysis, a series of generic tornado scenarios for different Enhanced Fujita (EF) ratings are simulated, and five resilience metrics are assigned to represent community goals based on economic and population stability. To accomplish this, the functionality of the buildings following the simulated tornado is used as input to a computable general equilibrium (CGE) economics model that predicts household income, employment, and domestic supply at the community level. Population dislocation as a function of building damage and detailed sociodemographic US census-based data is also predicted and serves as a core community resilience metric. Finally, this proposed methodology demonstrates how the metrics can help meet community-level resilience objectives for decision support based on a level of design code improvement or retrofit level. The method is demonstrated for Joplin, Missouri. All analyses and data have been developed and made available on the open-source IN-CORE modeling environment. The proposed multidisciplinary methodology requires continued research to characterize the uncertainty in the decision support results.
Routledge Handbook of Sustainable and Resilient Infrastructure, 2018
The intent of current building codes for typical commercial and residential buildings is to safeg... more The intent of current building codes for typical commercial and residential buildings is to safeguard against loss of life to building occupants by minimizing the probability of structural collapse during natural hazard events. However, preserving building functionality after a natural hazard is not the primary consideration in current codes. Widespread building damage, and degradation or loss of building functions, can have severe social and economic impacts on a community. To reduce the likelihood and severity of potential property damage and to enable more rapid recovery for communities impacted by natural hazards, the U.S. Senate tasked the National Institute of Standards and Technology (NIST) with identifying research needs and implementation activities to develop a multi-hazard immediate occupancy (IO) performance objective for commercial and residential buildings. This new IO performance objective would provide the technical criteria needed to design a building to retain its ...
Recent events such as the 2011 Christchurch, New Zealand earthquake, the 2011 Great Tohoku, Japan... more Recent events such as the 2011 Christchurch, New Zealand earthquake, the 2011 Great Tohoku, Japan earthquake and tsunami, and Superstorm Sandy in 2012 have highlighted the need to better understand and model community resilience. This is particularly true with regard to interdependencies among physical infrastructure components and systems that exacerbate their lack of functionality and delay community recovery. The National Institute of Standards and Technology (NIST) funded the multi university five-year Center of Excellence for Risk-Based Community Resilience Planning (CoE), headquartered at Colorado State University. The Center’s purpose is to (i) develop a computational environment with fully integrated supporting databases to identify, study and understand the key attributes that make communities resilient; (ii) standardize data ontologies for community resilience; (iii) validate the computational environment through hindcasting of events and resilience-based field studies; an...
The concept of community resilience is a complex, multi-dimensional problem that relies on social... more The concept of community resilience is a complex, multi-dimensional problem that relies on social science, engineering, earth sciences, economics, and other disciplines to improve the way communities prepare for, resist, respond to, and recover from disruptive events. Community resilience can break the cycle of destruction and recovery and reduce the impacts of earthquakes and other hazards. This requires community planning for recovery of function and setting of recovery goals prior to the occurrence of hazard events to minimize social and economic disruptions. Investigations of lifeline system performance, interdependencies, and corresponding impacts on communities following earthquakes and other disasters around the world have highlighted the need for a new approach to improve the earthquake resilience of lifelines. In 2013, the National Institute of Standards and Technology (NIST) funded a project, led by the Applied Technology Council (ATC), that resulted in the NIST GCR 14-917...
At the present time, there is a lack of understanding of the performance of structures as complet... more At the present time, there is a lack of understanding of the performance of structures as complete systems under extreme loading conditions such as realistic, uncontrolled fires. Current specifications for the design of steel structures in the U.S. do not require structural engineers to design for fire conditions. A key issue in evaluating the response of structural systems to fire effects is the response of the structural system, including connections. The typical design procedure of representing connections as fixed or pinned is inadequate when evaluating structural response to fire. This paper presents a first step towards developing a simplified representation of simple shear tab connections for use in structural analysis and design. First, recently developed temperature-dependent material models for different types of steels are implemented. Finite Element (FE) analyses of coupon models are performed to verify the implementation of these material models. Detailed, solid-element...
Engineering Journal-american Institute of Steel Construction Inc, 2014
Performance-based methodologies to evaluate the fire performance of structures are needed to move... more Performance-based methodologies to evaluate the fire performance of structures are needed to move beyond the prescriptive procedures presently in use, which cannot be used to determine actual structural performance in fire. Analytical methods are needed for simulating the performance of structural systems, including connections, subject to realistic fire effects. Framing connections may be subject to large unanticipated deformations and loads during fire events, and connection failure may lead to other failures or local collapse. This paper presents the development of detailed finite element models of typical moment connections for steel framed structures. These detailed models incorporate temperature-dependent material models that have been calibrated against available test data from tensile coupons, including the modeling of necking behavior and fracture. The detailed connection models are loaded to failure to identify the applicable failure mechanisms. Connection performance at a...
Performance-based methodologies to evaluate the fire performance of structures are needed to move... more Performance-based methodologies to evaluate the fire performance of structures are needed to move beyond the prescriptive procedures currently in use, which cannot be used to determine actual structural performance in fire. Analytical methods are needed for simulating the performance of structural systems, including connections, subject to realistic fire effects. Framing connections may be subject to large, unanticipated deformations and loads during fire events, and connection failure may lead to other failures or local collapse. This paper presents the development of detailed finite element models of typical moment connections for steel-framed structures. These detailed models incorporate temperature-dependent material models that have been calibrated against available test data from tensile coupons, including the modeling of necking behavior and fracture. The detailed connection models are loaded to failure to identify the applicable failure mechanisms. Connection performance at ...
Journal of Structural Engineering-asce, 2018
ASCE 7 is moving toward adopting load requirements that are consistent with risk-informed design ... more ASCE 7 is moving toward adopting load requirements that are consistent with risk-informed design goals characteristic of performance-based engineering (PBE). ASCE 7-10 provided wind maps that correspond to return periods of 300, 700, and 1,700 years for Risk Categories I, II, and combined III/IV, respectively. The risk targets for Risk Categories III and IV buildings and other structures (designated as essential facilities) are different in PBE. The reliability analyses reported in this paper were conducted using updated wind load data to (1) confirm that the return periods already in ASCE 7-10 were also appropriate for risk-informed PBE, and (2) to determine a new risk-based return period for Risk Category IV. The use of data for wind directionality factor, K d , which has become available from recent wind tunnel tests, revealed that reliabilities associated with wind load combinations for Risk Category II structures are, in fact, consistent with the reliabilities associated with the ASCE 7 gravity load combinations. This paper shows that the new wind maps in ASCE 7-16, which are based on return periods of 300, 700, 1,700, and 3,000 years for Risk Categories I, II, III, and IV, respectively), achieve the reliability targets in Section 1.3.1.3 of ASCE 7-16 for nonhurricane wind loads.
Journal of Structural Engineering, 2020
Natural Hazards Review, 2020
In 2017, United States damages from natural hazard events exceeded $300 billion, suggesting that ... more In 2017, United States damages from natural hazard events exceeded $300 billion, suggesting that current targets for building performance do not sufficiently mitigate loss. The significant costs borne by individuals, insurers, and government do not include impacts from social disruption, displacement, and subsequent economic and livelihood effects. In 2016, Congress mandated the National Institute of Standards and Technology develop a report (NIST SP 1224) describing the research needs, implementation activities, and engineering principles necessary to improve the performance of residential and commercial buildings subjected to natural hazards. An immediate occupancy performance objective (IOPO) could help preserve building and social functions post event, minimizing physical, social, and economic disaster. The stakeholder-informed NIST report sets forth items needed for multihazard building design that can support enhanced resilience decision making. This paper highlights the social and economic considerations that require additional research, particularly with regard to feasibility and potential impacts from an IOPO. These topics must be considered prior to and throughout the IOPO technical development and community implementation processes to ensure better outcomes after natural hazard events.
Sustainable and Resilient Infrastructure, 2018
Journal of Structural Engineering, 2018
ASCE 7 is moving toward adopting load requirements that are consistent with risk-informed design ... more ASCE 7 is moving toward adopting load requirements that are consistent with risk-informed design goals characteristic of performance-based engineering (PBE). ASCE 7-10 provided wind maps that correspond to return periods of 300, 700, and 1,700 years for Risk Categories I, II, and combined III/IV, respectively. The risk targets for Risk Categories III and IV buildings and other structures (designated as essential facilities) are different in PBE. The reliability analyses reported in this paper were conducted using updated wind load data to (1) confirm that the return periods already in ASCE 7-10 were also appropriate for risk-informed PBE, and (2) to determine a new risk-based return period for Risk Category IV. The use of data for wind directionality factor, K d , which has become available from recent wind tunnel tests, revealed that reliabilities associated with wind load combinations for Risk Category II structures are, in fact, consistent with the reliabilities associated with the ASCE 7 gravity load combinations. This paper shows that the new wind maps in ASCE 7-16, which are based on return periods of 300, 700, 1,700, and 3,000 years for Risk Categories I, II, III, and IV, respectively), achieve the reliability targets in Section 1.3.1.3 of ASCE 7-16 for nonhurricane wind loads.
Journal of Structural Engineering, 2016
AbstractEstablishing consistent criteria for assessing the performance of structural systems and ... more AbstractEstablishing consistent criteria for assessing the performance of structural systems and infrastructure networks is a critical component of communities’ efforts to optimize investment decisions for the upkeep and renewal of the built environment. Although member-level performance and reliability assessment procedures are currently well-established, it is widely recognized that a member-oriented approach does not necessarily lead to an efficient utilization of limited resources when making decisions related to the management of existing deteriorating structures or lifeline systems, especially those that may be exposed to extreme events. For this reason, researchers have renewed their interests in developing system-level assessment methods as a basis to modern structural and infrastructure performance evaluation and design processes. Specifically, system-level performance metrics and characteristics such as reliability, redundancy, robustness, resilience, and risk continue to be refined. The objecti...
Structures, 2016
A key issue in evaluating the response of structural systems to fire effects is the representatio... more A key issue in evaluating the response of structural systems to fire effects is the representation of material behavior at elevated temperatures. In addition to stress-strain behavior, modeling of fracture is required to capture failure modes such as tear out in connection plates and bolt shear. Fracture can be simulated in explicit finite element analysis using element erosion, in which elements are removed from the analysis when specified failure criteria are satisfied. However, the basis for determining and implementing material failure criteria at elevated temperatures is not well-established in the literature. A finite element material modeling methodology is presented for structural steels and structural bolts at elevated temperatures that incorporates erosion-based modeling of fracture. Temperature-dependent stress-strain relationships for structural steel and structural bolts were combined with a plastic strain-based failure criterion for element erosion to enable modeling of fracture in analysis of structural connections and assemblies. The failure criterion was calibrated against high-temperature experimental data on elongation of tensile coupons at fracture, and its dependence on temperature and mesh size was investigated.
On the morning of September 11, 2001, Americans and people around the world were shocked by the d... more On the morning of September 11, 2001, Americans and people around the world were shocked by the destruction of the World Trade Center (WTC) in New York City and the devastation of the Pentagon near Washington, D.C., after large aircraft were flown into the buildings, and the crash of an aircraft in a Pennsylvania field that averted further tragedy. Four years later, the world has been changed irrevocably by those terrorist attacks. For some, the absence of people close to them is a constant reminder of the unpredictability of life and death. For millions of others, the continuing threats of further terrorist attacks affect how we go about our daily lives and the attention we must give to homeland security and emergency preparedness. Within the construction, building, and public safety communities, there arose a question pressing to be answered: How can we reduce our vulnerability to such attacks, and how can we increase our preparedness and safety while still ensuring the functionality of the places in which we work and live? This Investigation has, to the best extent possible, reconstructed the response of the WTC towers and the people on site to the consequence of the aircraft impacts. It provides improved understanding to the professional communities and building occupants whose action is needed and to those most deeply affected by the events of that morning. In this spirit, this report is dedicated to those lost in the disaster, to those who have borne the burden to date, and to those who will carry it forward to improve the safety of buildings.
Fire Technology, 2012
The National Institute of Standards and Technology (NIST) conducted an extensive investigation of... more The National Institute of Standards and Technology (NIST) conducted an extensive investigation of the collapse of World Trade Center towers (WTC 1 and WTC 2) and the WTC 7 building. This paper describes the reconstruction of impact damage to each of the WTC buildings, as well as analytical studies related to the WTC building collapses. In addition, data and evidence that were collected, tests of the floor truss systems in the WTC towers that were conducted, the overall structural analysis approach, and the development of the collapse hypotheses are discussed to provide a basis for the impact analyses and the fire and structural response analyses in a companion paper. Three companion papers address the primary structural systems of the WTC towers and WTC 7, the effects of fire on the three buildings, and how these events contributed to building collapse. The papers provide an overview of the complex and extensive investigations undertaken by NIST at a level of detail that has scientific merit but presents key aspects from the voluminous official reports at a level suitable for the technical literature.
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Papers by Therese McAllister