A component model for the behaviour of steel joints at elevated temperatures

Abstract

Recent experimental evidence has shown that steel joints exhibit a distinct change in their moment-rotation response under increasing temperature. In terms of cold design, the component method is currently the widely accepted procedure for the evaluation of the various design values. It is the purpose of the present paper to extend the component method to the prediction of the response of steel joints under fire loading. Using typical mechanical models consisting of extensional springs and rigid links, whereby the springs exhibit a non-linear force deformation response (here taken as a bi-linear approximation), an analytical procedure is proposed capable of predicting the moment-rotation response under fire conditions that incorporates the variation of yield stress and Young's modulus of the various components as the temperature increases. An application to a cruciform flush end-plate beam-to-column steel joint is presented and compared to the experimental results obtained under various loading conditions.

Alternative methods of identifying the moment – rotation characteristics related to the fire conditions

“…W tym przypadku poszukiwane relacje skojarzone z sytuacją poŜaru przy załoŜonych wartościach temperatury węzła są wyznaczane przez odpowiednią korektę takiej wyjściowej charakterystyki. Algorytm tego typu postępowania został szczegółowo opisany przez autorów w pracach [3] i [4], na podstawie sugestii zawartych w publikacji [7]. Drugie podejście (alternatywne względem pierwszego) opiera się na uwzględnieniu wpływu temperatury juŜ na etapie analizy potencjalnych mechanizmów zniszczenia, skojarzonych z poszczególnymi elementami węzła, a następnie na składaniu tych mechanizmów zgodnie z kanonem klasycznej metody składnikowej.…”

The development of a component-based connection element for endplate connections in fire

“…LestonJones 3 was the first to apply the method to his cruciform tests; Al-Jabri 4 used the method to model the flexible endplate behaviour of his high temperature experiments, and Spyrou 5 conducted a large number of high-temperature component tests and combined the investigated components using a simple two spring model. Simones da Silva et al 6 used the component models given in EC3-1.8, in combination with the temperature reduction factors given in EC3- 1.2 7 , to model the above-mentioned cruciform tests. However, none of these studies combined the Component Method directly with whole-frame action.…”

“…Hence the stiffness matrix in equation (5) is expanded to three dimensions and n bolt rows, as shown in equation (6). …”

Numerical Study on the Structural Performance of Steel Beams with Slant End-plate Connections

“…Dai et al (2010) witnessed various failure modes in the results of fire tests simulations of restrained steel beamcolumn assemblies adopting five different types of joints, signifying the importance of connection type details in thermal load resistance. Simões da Silva et al (2001) had extended the commonly practiced component method to the prediction of the response of steel joints under fire loading, focusing on a cruciform flush end-plate beam-to-column connection and comparing it to the experimental results obtained under various loading conditions. Realizing that restraint against thermal expansion of the beams can produce large axial forces, Heidarpour and Bradford (2009) presented an elastic analysis of a panel zone in a steel frame at elevated temperatures, joined in a rigid or semi-rigid fashion.…”