Author: Wood, R H
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Wood, R H
The Structural Engineer, Volume 52, Issue 7, 1974
A numerical procedure to determine the load-deformation response, up to the point of instability, of restrained steel beam-columns under biaxial bending is presented in this paper. The rotational restraints and the end loads need not be symmetric. The member is prismatic, originally straight and untwisted. The influence of residual strains as well as the warping strains that result from the twisting of the cross-section of column are included in the analysis. The equilibrium equations are written with respect to an arbitrary system of co-ordinate axes. This way the shift in the shear centre, and the shift and rotation of principal axes of the elastic core, as the yielding of the cross-section progresses is taken care of automatically. S. Vinnakota and Y. Aoshima
Dr. E. C. Hambly (M) : I wish to challenge the authors' statement that grillage analysis is inappropriate for decks with less than four cells. I will substantiate this challenge by demonstrating that the shear-flexible grillage can be used to reproduce the structural behaviour of a box-girder deck with the accuracy of a more sophisticated technique. I advocate grillage analysis of cellular decks because-it is an automatic method which does not require a high level of concentration in the design office over a long period, it is relatively inexpensive for analysis of multiple load cases, it can accommodate variations of geometry in plan and section, and it can be used with accuracy. There are shortcomings but they are no worse than those associated with grillage analysis of beam and slab decks. I should add that my enthusiasm for grillage analysis has developed considerably since I changed to the C&CA program which has very simple and clear data praparation and output.
In my circular letter dated 28 February 1974, written on behalf of both the Department of Education and Science and the Department of the Environment, as is this letter, I suggested the precautions which might be taken pending a report from the Building Research Establishment on their investigation into the causes of the failure of precast prestressed high alumina cement concrete roof beams over the swimming pool at the Sir John Cass Foundation and Red Coat School, Stepney. I also undertook to write to you again as soon as further information became available from the Building Research Establishment. An interim statement is given below. C.F.R. Barclay