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PROCEEDINGS OF THE SIXTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY
Edited by: B.H.V. Topping and Z. Bittnar
A Modified Algorithm for Reinforced Concrete Cross Section Integration
J.L. Bonet+, P.F. Miguel+, M.L. Romero* and M.A. Fernandez+
+Construction Engineering and Civil Engineering Projects Department, Polythecnic University, Valencia, Spain
J.L. Bonet, P.F. Miguel, M.L. Romero, M.A. Fernandez, "A Modified Algorithm for Reinforced Concrete Cross Section Integration", in B.H.V. Topping, Z. Bittnar, (Editors), "Proceedings of the Sixth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 120, 2002. doi:10.4203/ccp.75.120
Keywords: nonlinear analysis, reinforced concrete, stress integration, cross-section analysis, Gauss-Legendre quadrature, biaxial bending.
This paper deals with the implementation of a modified integration procedure for arbitrary geometry reinforced concrete cross sections with axial forces and biaxial bending, from service load to ultimate load. The proposed method is applicable in sections which stress field is uniform at least in one direction. The method decompose the integration area in thick layers parallel to the most tensile stressed fibre, which definition depends on the constitutive equation of the concrete. The integration of the stress field of each thick layer is transformed into a path integral over the perimeter of this layer, evaluating them by the Gauss-Legendre cuadrature. The fundamentals of the method are explained in the paper and different possibilities for this purpose are analysed. The obtained results for the different alternatives are compared in accuracy and in speed in relation with the results obtained with the classical fibre decomposition method, Mari , and also with other methods proposed by same authors, Miguel et al.  and Bonet et al.  and a recently method proposed by Fafitis . In the study among the four analysed methods (Cells, Fafitis, "Thick Layers Integration" and "Modified Thick Layers Integration"), applied in different concrete section types, the following conclusions are achieved:
Finally, the proposed "modified thick layers" method (MTLI), regarding the accuracy, efficiency, and continuity in the stress field integration it is advisable for the implementation in nonlinear reinforced concrete frameworks programs.
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