Using Opensees for Structures in Fire

Usmani, Asif; Jian, Zhang; Jian, Jiang; Jiang, Yuwu; May, Ian

doi:10.1260/2040-2317.3.1.57

Cited by 32 publications

(18 citation statements)

References 11 publications

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“…OpenSees is effectively a library of advanced computational tools for the nonlinear analysis of structures. The OpenSees framework is being extended at the University of Edinburgh by adding classes that introduce into OpenSees the capability of performing analyses of structures in fire including both heat transfer and thermo-mechanical analysis [25]. This work aims to enable the analyst to perform state of the art nonlinear analysis of structures under different situations (fire or earthquake) or multi-hazard (fire after earthquake) in a single numerical tool.…”

Section: Structural Layoutmentioning

confidence: 99%

The World Trade Center 9/11 Disaster and Progressive Collapse of Tall Buildings

Kotsovinos

Usmani

2012

Fire Technol

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Abstract. The collapse of the World Trade Center buildings on September 11, 2001 posed questions on the stability of tall buildings in fire. Understanding the collapse of the WTC Towers offers the opportunity to learn useful engineering lessons in order to improve the design of future tall buildings against fire induced collapse. This paper extends previous research on the modelling of the collapse of the WTC Towers on September 11, 2001 using a newly developed ''structures in fire'' simulation capability in the open source software framework OpenSees. The simulations carried out are validated by comparisons with previous work and against the findings from the NIST investigation, albeit not in the forensic sense. The column ''pull in'' that triggers the instability of the structure and leads to collapse is explained. The collapse mechanisms of generic composite tall buildings are also examined. This is achieved through carrying out a detailed parametric study varying the relative stiffness of the column and the floors. The two main mechanisms identified in previous research (weak and strong floor) are reproduced and criteria are established on their occurrence. The analyses performed revealed that the collapse mechanism type depended on the bending stiffness ratio and the number of floors subjected to fire and that the most probable type of failure is the strong floor collapse. The knowledge of these mechanisms is of practical use if stakeholders wish to extend the tenability of a tall building structure in a major fire.

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Section: Structural Layoutmentioning

confidence: 99%

The World Trade Center 9/11 Disaster and Progressive Collapse of Tall Buildings

Kotsovinos

Usmani

2012

Fire Technol

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“…OpenSees capability to model structures has been verified previously at ambient temperature Asgarian and Jalaeefar, 2011;Asgarian et al, 2010Asgarian, 2012, 2014) and at elevated temperature Usmani et al, 2012) against several experimental observations and analytical calculations. As this capability has been verified, no verification analysis was performed in this study.…”

Section: Model Verificationmentioning

confidence: 80%

Structural response of a MRF exposed to travelling fire

Rezvani

Ronagh

2015

Proceedings of the Institution of Civil Engineers - Structures

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2In this study, structural response of a seismically designed steel moment-resisting frame subjected to travelling fire is investigated. This is to determine the structural strength of a generic frame designed for an extreme load when subjected to fire as another extreme load in addition to quantifying the effect of travelling fire size on its collapse behaviour. In this study, using the concept of travelling fire, and calculating the thermal field applied to structural elements, a generic frame was examined against a family of fires travelling across its first floor. In this regard, the resolved far-field gas temperatures dependent on the distance to the centre of fire were considered in order to calculate the temperature at the unprotected steel members. Analysis results revealed that fire size can deeply affect the total collapse time of a frame so that by reducing the fire size to a half or a quarter, collapse time increases by 19% and 62%, respectively. It was also suggested that columns of such structures should be designed against travelling fire considering the effect of load redistribution by which axial forces of columns might be doubled compared to the nominal loads applied to them prior to fire.

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“…So far, the thermal analysis and structural analysis has been uncoupled in OpenSees, which means that temperature distribution along the element should be provided as input before the structural analysis. Parallel work is under progressing on automatically generating time-varying structural temperature data from a heat transfer analysis within OpenSees (Usmani et al 2012), however, direct inputs will always be required for modeling of experiments. A series of parameters containing time points and corresponding temperature for the nine temperature points along the height of the section respectively are defined as the input of ThermalLoad-Pattern.…”

Section: Class Diagrams For Thermomechanical Analysis In Openseesmentioning

confidence: 99%

OpenSees Software Architecture for the Analysis of Structures in Fire

Jian

Jiang

Kotsovinos

et al. 2015

J. Comput. Civ. Eng.

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Computational modeling of structures subjected to extreme static and dynamic loads (such as snow, wind, impact, and earthquake) using finite-element software are part of mainstream structural engineering curricula in universities (at least at graduate level), and many experts can be found in industry who routinely undertake such analyses. However, only a handful or institutions around the world teach structural response to fire (at any level) and only a few of the top consulting engineers in the world truly specialize in this niche area. Among the reasons for this are the lack of cheap and easily accessible software to carry out such analyses and the highly tedious nature of modeling the full (often coupled) sequence of a realistic fire scenario, heat transfer to structure and structural response (currently impossible using a single software). The authors in this paper describe how finite-element software can be extended to include the modeling of structures under fire load. The added advantage of extending existing finite-element codes, as opposed to creating fire-specific applications, is due to ability to perform multihazard type analysis, e.g., fire following earthquake. Due to its open source nature and object-oriented design, the OpenSees software framework is used for this purpose. In this work, the OpenSees framework, which was initially designed for the earthquake analysis of structures, is extended by the addition of new concrete classes for thermal loads, temperature distributions across element cross sections, and material laws based on Eurocodes. Through class and sequence diagrams, this paper shows the interaction of these classes with the existing classes in the OpenSees framework. The performance of this development is tested using benchmark solutions of a single beam with finite stiffness boundary conditions and a steel frame test. The results from OpenSees agree well with analytical solutions for the benchmark problem chosen and provide reasonable agreement with the test. The experience with OpenSees so far suggests that it has excellent potential to be the basis of a unified software framework for enabling computational modeling of realistic fires, and further work is continuing towards the achievement of this goal. The extensions made to OpenSees described in this work, in keeping with the open source ideals of the framework, have been included in the current OpenSees code and are available for researchers and practicing engineers to test, develop, and use for their own purposes.

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Using Opensees for Structures in Fire

Cited by 32 publications

References 11 publications

The World Trade Center 9/11 Disaster and Progressive Collapse of Tall Buildings

The World Trade Center 9/11 Disaster and Progressive Collapse of Tall Buildings

Structural response of a MRF exposed to travelling fire

OpenSees Software Architecture for the Analysis of Structures in Fire

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