Proposed Effective Width Criteria for Composite Bridge Girders
Publication: Journal of Bridge Engineering
Volume 12, Issue 3
Abstract
In a composite section, in-plane shear strain in the slab (acting as a flange in the composite girder) under the applied bending causes the longitudinal displacements in the parts of the slab remote from the webs to lag behind those near the webs. This phenomenon, termed shear-lag, can result in an incorrect calculation of the displacement and extreme fiber stresses when using only the elementary theory of beam bending. The effective width concept has been introduced, widely recognized, and implemented into different codes of practice around the world as a simplified practical method for design and evaluation of structural strength and stiffness while accounting for shear-lag effects indirectly. Each code implements different ideas and approaches for specifying effective width. This paper proposes simpler and more versatile design criteria for computing the effective width in steel-concrete composite bridges. A parametric study was conducted based on finite-element analysis of bridges selected by a statistical method—namely, design of experiment concepts. Both simple-span and multiple-span continuous bridges were considered in the parametric study. The finite-element methodology was validated with companion experiments on 1/4- and 1/2-scale specimens. Effective width values at the critical sections were computed from stresses extracted from FEM models and used in developing candidate design equations. The final design criteria were selected based on assessment of impact of candidate equations. Use of full width—the most versatile, simplest, and sufficiently accurate effective width design criteria, is proposed for both positive and negative moment regions.
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Acknowledgments
This work was sponsored by the American Association of State Highway and Transportation Officials, in cooperation with the Federal Highway Administration, and was conducted in the National Cooperative Highway Research Program, which is administered by the Transportation Research Board of the National Research Council. The opinions and conclusions expressed or implied in this paper are those of the writers. They are not necessarily those of the Transportation Research Board, the National Research Council, the Federal Highway Administration, the American Association of State Highway and Transportation Officials, or the individual states participating in the National Cooperative Highway Research Program.
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Information & Authors
Information
Published In
Journal of Bridge Engineering
Volume 12 • Issue 3 • May 2007
Pages: 325 - 338
Copyright
© 2007 ASCE.
History
Received: Aug 31, 2005
Accepted: Jun 2, 2006
Published online: May 1, 2007
Published in print: May 2007
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