Effective Slab Width Definition for Negative Moment Regions of Composite Bridges
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Volume 12, Issue 3
Abstract
Currently, the AASHTO-LRFD design code specifies the same effective slab width design criteria for both positive moment sections and negative moment sections. The only difference in computing effective slab width between the positive and negative moment regions is the value of effective span length , the definition of which is problematic. The effective slab width concept for the positive moment regions has been investigated by many researchers. However, the classical effective slab width definition does not take into account both the strain variation through the slab thickness and the mechanism that redistributes load from concrete to steel reinforcement after cracking. In this paper, a more robust effective slab width definition for the negative moment section is introduced to account for these factors. The proposed definition is developed for negative moment regions and explored by using the finite-element method (FEM). The finite-element modeling scheme is briefly discussed, and the model is successfully verified with experimental results. Numerical results show the simplicity, accuracy, and robustness of the proposed definition in extracting effective slab width values from FEM results. Numerical results also indicate that the effective slab width criteria in the current AASHTO-LRFD Specifications is typically conservative for larger girder spacings. Detailed calculations of effective slab width for the negative moment regions using the proposed definition are summarized at the end of this paper.
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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.
References
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Information & Authors
Information
Published In
Journal of Bridge Engineering
Volume 12 • Issue 3 • May 2007
Pages: 339 - 349
Copyright
© 2007 ASCE.
History
Received: Dec 14, 2005
Accepted: Mar 3, 2006
Published online: May 1, 2007
Published in print: May 2007
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