References of "Nadjai, Ali"
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See detailFull-scale fire test on a composite floor slab incorporating long span cellular steel beams
Nadjai, Ali; Bailey, Colin; Vassart, Olivier et al

in Structural Engineer (2011), 89(21), 18-25

As part of an international major research initiative, dealing with the behaviour of long span cellular beams in steel framed buildings under fire, a large-scale fire test incorporating 15m long cellular ... [more ▼]

As part of an international major research initiative, dealing with the behaviour of long span cellular beams in steel framed buildings under fire, a large-scale fire test incorporating 15m long cellular beams was carried out. The test incorporated unprotected secondary cellular steel beams acting compositely with the supporting floor slab. The floorplate in its entirety was designed to carry the load with unprotected beams, when subjected to a severe fire, by utilising membrane action of the floor slab. The overall structure performed very well supporting the full applied static load for the duration of the test. The unprotected cellular steel beams were subjected to distortional buckling, with only the top tee providing any support through catanary action. The test supported the assumptions adopted in the structural design approach and provided an accurate estimate of the strength of the floorplate. Comparison of the recorded time-temperature relationship of the fire with the design method presented in the Eurocodes shows that the code under-predicts the severity of the fire, although this was compensated to some extent by the conservative assumptions embedded within the structural model. [less ▲]

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See detailFire resistance of long span cellular beam made of rolled profiles
Vassart, Olivier; Hawes, Mike; Simms, Ian et al

Report (2011)

The aim of this document is to describe the calculation methods developed to assess the resistance of simply supported cellular beams in fire conditions. This development has been made in the scope of the ... [more ▼]

The aim of this document is to describe the calculation methods developed to assess the resistance of simply supported cellular beams in fire conditions. This development has been made in the scope of the RFCS FiCEB+ [23] and in the scope of the PHD of O.Vassart [24]. This calculation procedure has been introduced in the ACB+ software available on www.arcelormittal.com/sections [23] RFS2-CT-2007-00042 : FICEB+ - Fire resistance of long span cellular beam made of rolled profiles ; March 2011 [24] O. Vassart, Analytical model for cellular beams made of hot rolled sections in case of fire, PhD Thesis, Université Blaise Pascal Clermont-Ferrand II, 2009 [less ▲]

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See detailLarge-scale fire test of unprotected cellular beam acting in membrane action
Vassart, Olivier; Bailey, C. G.; Hawes, M. et al

in Franssen, Jean-Marc; Kodur, Venkatesh (Eds.) Proceedings of the Sixth International Conference Structures in Fire (2010, June)

This paper describes a full scale fire test performed recently on a composite floor for analysing the possibility of tensile membrane action to develop when the unprotected steel beams in the central part ... [more ▼]

This paper describes a full scale fire test performed recently on a composite floor for analysing the possibility of tensile membrane action to develop when the unprotected steel beams in the central part of the floor are made of cellular beams. The natural fire was created by a wood crib fire load of 700 MJ/m² and the 9 x 15 m floor survived the fire that peaked at 1000°C and lasted for 90 minutes. Blind predictions of the air temperature development by the software Ozone and of the structural behaviour by the software SAFIR which proved quite satisfactory are also described. [less ▲]

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See detailParametrical study on the behaviour of steel and composite cellular beams under fire conditions
Vassart, Olivier; Bailey, C. G.; Bihina, Gisèle et al

in Kodur, Venkatesh; Franssen, Jean-Marc (Eds.) Structures in Fire. Proceedings of the Sixth International Conference (2010)

This paper describes an extensive parametric study on the behaviour of cellular beam under fire conditions. Different finite element models using shell elements were developed considering both material ... [more ▼]

This paper describes an extensive parametric study on the behaviour of cellular beam under fire conditions. Different finite element models using shell elements were developed considering both material and geometrical non-linearity; CAST3M [1], ANSYS [2] and another one in SAFIR [3]. They were calibrated on the basis of a new experimental test campaign performed in the scope of the project FICEB+ [4] funded by the Research Fund for Coal and Steel. The comparison between the finite element prediction and actual experimental results showed a good agreement in terms of failure modes, load deflection relationship and ultimate loads. At failure, temperature measured during the fire tests indicated that failure arising by web post buckling of cellular beams in fire cannot be simply estimated by applying temperature dependent reduction factors on strength alone, as given in codes. A design model representing the behaviour of cellular beam in fire conditions has been developed by Vassart [5-7]. This design model is able to predict the complex behaviour of cellular beam in case of fire comprising web-post buckling and Vierendeel bending, as well as standard flexural bending. The results of the Finite Element Models are compared in terms of critical temperatures and failure mode obtained using the design model. This paper also contains some tests results that were used to calibrate the FEM model and the comparison between analytical and FEM models. [less ▲]

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