PSI - Issue 84

Gian Felice Giaccu et al. / Procedia Structural Integrity 84 (2026) 991–998

997

3. Conclusions This study introduces an extended effective width concept specifically formulated to address pure compression scenarios in the design of composite bridge decks. Developed through an extensive parametric investigation using Finite Element analysis, the proposed methodology provides a practical and efficient framework for estimating stress distributions in composite decks subjected to combined axial and bending loads. The approach is particularly suited for engineering practice, as it relies on simplified beam-based models, avoiding the computational burden associated with full three-dimensional finite element simulations. The key contributions of this research can be summarized as follows: • Identification of limitations in existing code-based provisions for effective width, particularly in the context of cable-stayed bridges where significant axial–bending interaction occurs; • Validation of a simplified design methodology for twin-girder composite decks applicable at both the Ultimate Limit State and the Serviceability Limit State, explicitly accounting for connector deformability; • Introduction of a non-dimensional Aspect Ratio parameter, which enables generalization of the method across diverse cross-sectional geometries and bridge configurations; • Confirmation that a 30° projection angle is suitable for estimating effective width under axial loading, in line with recommendations from AASHTO and consistent with stress diffusion behavior observed in segmental concrete box girder bridges (EN 1992-1-1:2004). These findings contribute to bridging the gap between advanced numerical modeling and practical design methodologies, offering a robust and accessible tool for the analysis and verification of composite bridge decks in complex loading scenarios. Acknowledgements This work has been supported by the project “Metamaterials design and synthesis with applications to infrastructure engineering” funded by the MUR Progetti di Ricerca di Rilevante Interesse Nazionale (PRIN) Bando 2022 - Grant 20228CPHN5. Numerical simulations by finite elements were carried out on the computers of the Department of Civil and Environmental Engineering and Architecture (DICAAR), University of Cagliari (Italy), using a licensed commercial software. The University of the Republic of San Marino is gratefully acknowledged for the support in the framework of the Research Project PRIU2024. References AASHTO. LRFD Bridge Design Specifications. Washington, D.C.: American Association of StateHighway and Transportation Officials, 1994. AASHTO. LRFD Bridge Design Specifications, in: Am. Assoc. State Highw. Transp. Off. 2017. Abdelhakim K., Houari M.S.A., Bousahla A.A., Mahmoud S.R. Post-buckling analysis of shear-deformable composite beams using a novel simple two-unknown beam theory. Structural Engineering & Mechanics 2018;65(5):621-631. Adekola A.O. Effective width of composite beams of steel and concrete. The Structural Engineer 1968;46(9):285-289. Adekola A.O. The dependence of the shear-lag on partial interaction in composite beams. Int. Journal of Solids and Structures 1974;10:389-400. Baertschi R., Garcia S., Kroyer R., Sutter P. Deformation capacity and ductility of shear connectors. In: Proceedings in civil engineering, 9th international conference on composite construction in steel and concrete. Behnam A., Denavit M.D. Steel-concrete composite columns are efficient structural members that possess significant strength, stiffness, and ductility. Journal of Constructional Steel Research 2020;170:106092. Byers D. Evaluation of the Effective Slab Width for Composite Cable-Stayed Bridge Design. Ph. D. Thesis. University of Kansas;1999. Cai H., Aref A.J. Three-dimensional geometric nonlinear analysis of composite cable-stayed bridges using a refined double-beam model. Journal of Bridge Engineering 2014;19(6):04014017. CEN ECFS. Eurocode 4: Design of composite steel and concrete structures – Part 2: General rules and rules for bridges, Brussels: 2005. CEN. Eurocode 2: Design of concrete structures. European Committee for Standardisation TC250/SC8/, 2004. Chen S.S., Aref A.J., Ahn I.S., Chiewanichakorn M., Carpenter J.A., Nottis A., Kalpakidis I. Effective Slab Width for Composite Steel Bridge Members. 2005. Chen S., Zhang Z. Effective width of a concrete slab in steel–concrete composite beams prestressed with external tendons. Journal of Constructional Steel Research, 2006;62(5):493-500. Denavit M.D. Interaction strength of steel-concrete composite beam-columns including the balance point. In: 2020 Proceedings of the Annual Stability Conference Structural Stability Research Council.