Geometric non-linear modelling of partial interaction in composite T-beams in fire

Amin Heidarpour, Mark Andrew Bradford

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1 Citation (Scopus)


The formulation for partial shear interaction in composite beams was developed over 50 years ago in closed form. This formulation is suitable for many cases encountered in practice, but it does not account for the geometric non-linearity produced by the "P-delta" effect. This effect is important in a compartment in a steel or composite framed building in a fire, where the initially large compressive forces which develop because of restraint against thermal expansion interact non-linearly with the large deflections of the composite floor slab, and a geometrically non-linear formulation must necessarily be invoked to capture the partial interaction behaviour of the composite floor system during a fire. This paper provides an elastic analysis of partial interaction at moderately low levels of temperature, so as to shed light on the significance of the parameters that affect the structural behaviour as well as to provide a precursor for an inelastic analysis to treat catenary action. The differential equations which quantify the problem are derived and solved numerically, and an illustrative example is worked.

Original languageEnglish
Title of host publicationComposite Construction in Steel and Concrete VI - Proceedings of the 2008 Composite Construction in Steel and Concrete Conference
PublisherAmerican Society of Civil Engineers
Number of pages9
ISBN (Print)9780784411421
Publication statusPublished - 2011
Externally publishedYes
EventInternational Conference on Composite Construction in Steel and Concrete 2008 - Devil's Thumb Ranch, Tabernash, United States of America
Duration: 20 Jul 200824 Jul 2008
Conference number: 6th


ConferenceInternational Conference on Composite Construction in Steel and Concrete 2008
CountryUnited States of America
Internet address


  • Composite beams
  • Fires

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