Analysis of Structural Response of WTC 7 to Fire and Sequential Failures Leading to Collapse

McAllister, Therese P.; MacNeill, Robert; Erbay, Omer O.; Sarawit, Andrew T.; Zarghamee, Mehdi S.; Kirkpatrick, Steven W.; Gross, John L.

doi:10.1061/(asce)st.1943-541x.0000398

Cited by 9 publications

(5 citation statements)

References 2 publications

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“…Explicit modeling of the collapse of structures is a challenging task and the subject of current research [37][38][39][40]. The FEMA [2] methodology has avoided the need to explicitly model collapse by defining collapse in the context of IDA.…”

Section: Analysis Resultsmentioning

confidence: 99%

Seismic performance factors for moment frames with steel‐concrete composite columns and steel beams

Denavit¹,

Hajjar

Perea

et al. 2016

Earthq Engng Struct Dyn

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Summary Steel‐concrete composite moment frames have been shown to be an effective alternative for use as the primary seismic force‐resisting system of building structures. However, little data are available to justify the structural system performance factors (i.e., R, Cd, and Ωo) given in codes to characterize the overstrength and ductility of these systems. Reasonable values for these factors are vital for successful seismic design. Based on a suite of new finite element formulations, this work investigates the behavior of composite special moment frames under seismic loading and develops rational system performance factors according to the Federal Emergency Management Agency P695 methodology. A set of archetype frames, selected to be representative of the range of frames seen in practice, were designed according to current design specifications. Nonlinear static pushover and dynamic response history analyses were performed on the frames to generate the statistical data on the seismic response from which the performance factors are quantified. The results from this investigation enable a better understanding of the variability in collapse performance of composite frame systems and will facilitate more effective designs of these systems. Copyright © 2016 John Wiley & Sons, Ltd.

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Section: Analysis Resultsmentioning

confidence: 99%

Seismic performance factors for moment frames with steel‐concrete composite columns and steel beams

Denavit¹,

Hajjar

Perea

et al. 2016

Earthq Engng Struct Dyn

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“…Using FDS derived gas temperatures, NIST then calculated the temperatures in the structural members and varied them by ±10% to create three scenarios that envelope the potential building fires and account for uncertainties in the modelling [14,18].…”

Section: Nistmentioning

confidence: 99%

“…As will be shown in the results and discussion, this does not seem to affect the overall structural behaviour as the effects of the fire in the mechanical space remained localised. The mesh size of the fire-affected 7 th floor was approximately 0.5 m, while the 6 th floor slab was meshed with element size of about 0.7 m. These values are of the same order of magnitude as NIST's thermomechanical model which had element size of 0.9 m for the floor members [18]. The model had a total of 22,823 nodes and 22,978 elements.…”

Section: Model 1: Thermomechanical Model Of Mechanical Floorsmentioning

confidence: 99%

The Collapse of World Trade Center 7: Revisited

et al. 2022

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The catastrophic events of September 11, 2001, stand out as a major motivation for research on improving the understanding of structural behaviour in fire. These events included the first complete collapse of a tall steel framed structure solely due to fire. World Trade Center 7 (WTC7) was a 47storey office building within the WTC complex that collapsed due to a fire initiated by debris from the collapse of WTC1. In the following years, detailed investigations were carried out by expert teams to pinpoint the cause of the progressive failure of WTC7. Each of the expert teams analysed the fire and structure and made varying conclusions with regards to the mechanisms responsible for initiating and propagating the collapse of the building. This paper revisits the collapse of WTC7 and its investigation, and then explores the hypothesis that a potential hydrocarbon fire may have compromised the large transfer structure within the mechanical space of the building. This is done via two OpenSees finite element models. The first model explores the thermomechanical response of the mechanical floors to a potential diesel fire, and the second investigates the response of the structure to a failure caused by that fire. The outcome of the analyses shows that it is feasible that a mechanical room fire could lead to a failure in the transfer structure, which would then result in the loss of support to at least two columns within the building core. The failure of these columns may unbrace the eastern-most core columns and precipitate in the failure of the structure as observed on 9/11.

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“…Fu [4] made a 3D finite element modle to study the global behaviour of a multi-storey building in fire. A study on the WTC 7 (McAllister et al, [5]) made use of ANSYS and LS-DYNA to analysis dynamic structural and pseudo static responses respectively. By considering different temperature and debris-impacts, the several uncertainties around the sequence of events was investigated and the contributors to collapse was able to be identified.…”

Section: Introductionmentioning

confidence: 99%

Collapse Mechanism of a Space Structure Under Fire Conditions

Naqvi

2021

ce papers

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This paper investigates the collapse mechanism of a long span space structure under fire. The mechanical and thermal properties of a space structure change drastically when subjected to a fire. The nature in which the space structure fails is dependent on a number of factors including fire load, shape and properties of the space structure and its materials. In order to fully analyze how a space structure would fail in these conditions, a multi‐physics thermal mechanical analysis model was built in ANSYS software. The chosen prototype space structure, Kings Cross Wester Concourse roof is modeled. The models were created using a series of complex features and were made to be geometrically sound with alignments between each member. Coupled steady state thermal and static structural analysis was performed and collapse mechanism of the space structure under fire were investigated the effectiveness of using finite element analysis software for large assemblies' analysis is also discussed.

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Analysis of Structural Response of WTC 7 to Fire and Sequential Failures Leading to Collapse

Cited by 9 publications

References 2 publications

Seismic performance factors for moment frames with steel‐concrete composite columns and steel beams

Seismic performance factors for moment frames with steel‐concrete composite columns and steel beams

The Collapse of World Trade Center 7: Revisited

Collapse Mechanism of a Space Structure Under Fire Conditions

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