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Back-to-back lipped channels (I-section) under local vertical web-crushing load

Fig. 1. I-sections with stiffened flanges tested by Hetrakul and Yu [4] under ITF loading conditions and schematic of test set-up.

The citation is:
[4] N. Hetrakul, W. Yu, Webs for Cold-formed Steel Flexural Members; Structural Behaviour of Beam Webs Subjected to Web Crippling and a Combination of Web Crippling and Bending, University of Missouri-Rolla, Missouri, USA (1978)

This and the next 2 images are from:

P. Natanio (1), N. Silvestre (2) and D. Camotim (1)
(1) CERIS, ICIST, DECivil, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
(2) IDMEC, Department of Mechanical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal

“Web crippling of beams under ITF loading: A novel DSM-based design approach”, Journal of Constructional Steel Research, Vil. 128, pp 812-824, January 2017, DOI: 10.1016/j.jcsr.2016.10.011

ABSTRACT: A new approach to estimate the web crippling failure load of cold-formed steel beams under Internal Two Flange (ITF) loading using the Direct Strength Method (DSM) is proposed in this paper. After the description of the existing test data to calibrate the DSM-based formula, the accuracy of the analytical expressions given in Eurocode 3 [1] and the North-American Specification [2] is briefly assessed. In order to obtain additional information on the web crippling behaviour of each test specimen, several types of analyses are performed: (i) quasi-static non-linear analyses (using finite elements), (ii) elastic buckling analyses (using finite elements and the GBTWEB software), and (ii) rigid-plastic analyses (using yield-line theory). The coefficients of a DSM-based formula are determined on the basis of the set of 85 experimental results available in the literature and the corresponding buckling and plastic load values. In spite of the different cross-sections, fastening conditions and test set-ups considered in the calibration procedure, it is possible to establish a clear relationship between the web crippling slenderness and the nominal-to-plastic load ratio. Finally, it is shown that the proposed DSM-based formula for ITF loading yields reasonable predictions of web crippling loads and provides safe estimates of flange crushing loads.

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