Design Recommendations for Y-Shaped Shear Connectors in Fire-Exposed Composite Beams

Subject Areas : Structural Engineering in Energy-Efficient Buildings

Maede Davami ^{1 *} , علیرضا میرزا گل تبار روشن ² , Hamidreza Tavakoli ³

1 - 1 Department of Civil Engineering, Babol Noshirvani University of Technology (NIT), Babol, Mazandaran, Iran)
2 - دانشگاه صنعتی نوشیروان بابل، دانشکده مهندسی عمران
3 - Babol Noshirvani University of Technology

Received: 2025-10-25 Accepted : 2025-11-13 Published : 2025-10-07

Keywords: Y-shaped shear connector, composite beam, elevated temperature, design guideline, reduction factor, finite element analysis (FE),

Abstract :

This study proposes design-oriented recommendations for Y-shaped shear connectors used in steel–concrete composite beams subjected to elevated temperatures. A comprehensive numerical analysis was carried out using ABAQUS to evaluate the effect of connector geometry and material strength on load transfer performance under fire exposure. The parameters studied include connector diameter, height, width, inclination angle, and concrete compressive strength. Strength and stiffness reduction factors were derived for temperatures ranging from 25°C to 800°C. Based on the results, practical design equations and optimal geometrical configurations are proposed to enhance structural performance and safety under thermal conditions. The analysis revealed that both shear strength and stiffness decrease by up to 80% and 85%, respectively, at 800°C. Based on these results, practical design equations and optimal geometrical configurations are proposed. Based on validated FE analyses and extensive parametric studies, this paper proposes design-oriented recommendations for Y-shaped shear connectors used in composite steel–concrete beams under fire exposure. Critical factors affecting strength retention, stiffness, and ductility are summarized, and practical design guidelines are suggested. Additionally, future research directions such as the application of UHPC and FRP reinforcement for improved thermal resistance are discussed. The novelty of this study lies in providing validated reduction factors and design-oriented correlations for fire-resistant applications.

References:

[1] Oehlers, D. J., & Bradford, M. A. Composite Steel and Concrete Structural Members: Fundamental Behaviour. Oxford: Butterworth–Heinemann, Elsevier, 2015, 592 pages. ISBN: 9780080971640.
[2] Ollgaard, J. G., Slutter, R. G., & Fisher, J. W. “Shear Strength of Stud Connectors in Lightweight and Normal-Weight Concrete.” AISC Engineering Journal, Vol. 8, No. 2, pp. 55–64, 1971.




[3] Shanmugam, N. E., & Lakshmi, B. “State of the Art Review on Steel–Concrete Composite Beams.” Journal of Constructional Steel Research, Vol. 57, No. 10, pp. 1041–1080, 2001, Elsevier.
[4] Wang, W., & Kodur, V. “Response of Shear Connectors in Composite Beams at Elevated Temperatures.” Fire Safety Journal, Vol. 67, pp. 41–53, 2014, Elsevier.




[5] Vianna, J. N. S., Rodrigues, J. P. C., & da Silva, J. G. S. “Structural Behavior of Perfobond Rib Shear Connectors: Experimental and Numerical Evaluation.” Engineering Structures, Vol. 125, pp. 149–162, 2016, Elsevier.
[6] Kim, S., Park, J., & Kim, D. “Behavior of Steel–Concrete Composite Beams with Y-Type Shear Connectors.” Journal of Constructional Steel Research, Vol. 120, pp. 179–192, 2016, Elsevier.
[7] Ding, X., Zhang, J., & Nie, J. “Finite Element Modeling and Parametric Study on Y-Shaped Shear Connectors in Composite Beams.” Engineering Structures, Vol. 188, pp. 1–15, 2019, Elsevier.
[8] Chen, S., & Liu, Y.“A Parametric Study of Innovative Shear Connectors for Composite Beams.”Advances in Structural Engineering, Vol. 21, No. 12, pp. 1821–1835, 2018, SAGE Publications.
[9] Kodur, V. K. R. Fire Hazard in Concrete and Composite Structures. Springer Nature, 2016, 356 pages. ISBN: 9783319411443.
[10] Youssef, M. A.“Behavior of Composite Steel–Concrete Beams under Fire Conditions.”Journal of Structural Engineering (ASCE), Vol. 143, No. 5, pp. 04016221, 2017.
[11] European Committee for Standardization (CEN). EN 1994-1-2: Eurocode 4 – Design of Composite Steel and Concrete Structures, Part 1-2: Structural Fire Design. Brussels, 2023 revision.
[12] Zhao, X., Zhang, L., & Yan, X.“Fire Resistance of Shear Connectors in Composite Beams: Numerical and Experimental Investigations.”Fire Safety Journal, Vol. 114, pp. 103–118, 2020, Elsevier.
[13] Wang, X., & Han, L. H. “High-Temperature Behavior of Steel–Concrete Composite Interfaces and Connectors.” Journal of Constructional Steel Research, Vol. 179, pp. 106–541, 2021, Elsevier.
[14] Phan, L. T.“Thermal and Mechanical Degradation of Concrete at Elevated Temperatures.”Cement and Concrete Research, Vol. 105, pp. 42–52, 2018, Elsevier.
[15] Xu, L., & Sugiura, K. “3D Nonlinear Finite Element Modeling of Steel–Concrete Composite Beams.” Journal of Structural Engineering (ASCE), Vol. 143, No. 4, pp. 04016212, 2017.
[16] Hu, Y., Zhang, L., & He, M.“Fire Performance of Innovative Shear Connectors for Composite Beams.”Structures, Vol. 33, pp. 1091–1105, 2022, Elsevier.
[17] Nie, J., Ding, X., & Zhu, Y.“Effect of Connector Geometry on Mechanical Performance of Composite Beams.”Engineering Structures, Vol. 99, pp. 1–13, 2015, Elsevier.
[18] Ali, F., & Bradford, M. A.“Advanced FE Modelling of Composite Steel–Concrete Members under Fire.”Fire Safety Journal, Vol. 101, pp. 47–61, 2018, Elsevier.
[19] Saad, M., Serror, H., & Sennah, K.“Temperature-Dependent Behavior of Shear Connectors in Composite Slabs.” Steel and Composite Structures, Vol. 34, No. 5, pp. 631–648, 2020.
[20] He, J., Zhang, Y., & Huang, Q.“Thermal Effects on Composite Steel–Concrete Slabs with Various Connector Types.” Construction and Building Materials, Vol. 208, pp. 448–460, 2019, Elsevier.
[21] Wang, X., & Hu, Z.“Connector Configuration Influence on High-Temperature Performance of Composite Beams.” Engineering Structures, Vol. 283, pp. 115–104, 2023, Elsevier.