Numerical and Experimental Investigations on the Behavior of Steel-reinforced Concrete Columns Subjected to Eccentric Loading

Document Type : Original Article


1 Faculty of Civil Engineering, Babol Noshirvani University of Technology, Babol, Iran

2 Department of Civil Engineering, University of Mazandaran, Babolsar, Iran


Steel-reinforced concrete (SRC) columns, which are classified as composite columns, became the most widely used in recent years; because of their extensive advantages over the reinforced concrete and the steel columns. In this paper, the ductility index and its influential factors were explored to investigate the behavior of SRC columns. A straightforward approach was then proposed by establishing the necessary equations based on the plastic stress distribution method. Accordingly, an experimental program was performed on six SRC column specimens with two H- and cross-shaped steel sections and three eccentricity ratios of 0.4, 0.55, and 0.7. In addition, a finite element model was developed for numerical analysis using Abaqus software, which was verified by the experimental results. A total of 30 columns were thus analyzed for the parametric study where the effects of geometric and material variables, including steel percentage, concrete compressive strength, lateral tie spacing, and geometrical shape of the steel core on the ductility index of these columns were assessed. The results confirm that for the H-shaped column, reducing the lateral tie spacing ratio from 0.6 to 0.2 not only increases the ductility index to as much as 72%, it also induces a post-yield hardening in the load-displacement curve and increases the bearing capacity by 20%. Subsequently, load-bending moment interaction curves were developed according to plastic stress distribution method cited in EC4 Code and then compared with those obtained through the software. Thus, normalized curves were presented as a means to design these columns.


1.   Shariati, M., Sulong, N.R., Shariati, A. and Kueh, A., "Comparative performance of channel and angle shear connectors in high strength concrete composites: An experimental study", Construction and Building Materials,  Vol. 120, (2016), 382-392 DOI:
2.   Rahmani, Z., Naghipour, M. and Nematzadeh, M., "Flexural performance of high-strength prestressed concrete-encased concrete-filled steel tube sections", International Journal of Engineering,  Vol. 32, No. 9, (2019), 1238-1247 DOI: https://doi:10.5829/ije.2019.32.09c.03.
3.   Nematzadeh, M., Naghipour, M., Jalali, J. and Salari, A., "Experimental  study and calculation of confinement relationships for prestressed steel tube-confined compressed concrete
stub columns", Journal of Civil Engineering and
, Vol. 23, No. 6, (2017), 699-711 DOI:
4.   ECS, "Eurocode 4: En 1994-1-2: 2004: Design of composite steel and concrete structures. Part1-1: General rules–structural rules for buildings, ECS Brussels, Belgium,  (2004).
5.   An, Y.-F., Han, L.-H. and Roeder, C., "Performance of concrete-encased cfst box stub columns under axial compression", Structures,  Vol. 3, (2015), 211-226 DOI:
6.   An, Y.-F., Han, L.-H. and Roeder, C., "Flexural performance of concrete-encased concrete-filled steel tubes", Magazine of Concrete Research,  Vol. 66, No. 5, (2014), 249-267 DOI:
7.   Ellobody, E., Young, B. and Lam, D., "Eccentrically loaded concrete encased steel composite columns", Thin-walled Structures,  Vol. 49, No. 1, (2011), 53-65 DOI:
8.   Ellobody, E. and Young, B., "Numerical simulation of concrete encased steel composite columns", Journal of Constructional Steel Research,  Vol. 67, No. 2, (2011), 211-222 DOI:
9.   Chen, C.-C. and Lin, N.-J., "Analytical model for predicting axial capacity and behavior of concrete encased steel composite stub columns", Journal of Constructional Steel Research,  Vol. 62, No. 5, (2006), 424-433 DOI:
10. Mander, J.B., Priestley, M.J. and Park, R., "Theoretical stress-strain model for confined concrete", Journal of Structural Engineering,  Vol. 114, No. 8, (1988), 1804-1826 DOI:
11. Wang, H., Li, J. and Song, Y., "Numerical study and design recommendations of eccentrically loaded partially encased composite columns", International Journal of Steel Structures,  Vol. 19, No. 3, (2019), 991-1009 DOI:
12. Han, L.-H. and An, Y.-F., "Performance of concrete-encased cfst stub columns under axial compression", Journal of Constructional Steel Research,  Vol. 93, (2014), 62-76 DOI:
13. Zhou, X., Yan, B. and Liu, J., "Behavior of square tubed steel reinforced-concrete (src) columns under eccentric compression", Thin-walled Structures,  Vol. 91, (2015), 129-138 DOI:
14. Li, B., Park, R. and Tanaka, H., "Stress-strain behavior of high-strength concrete confined by ultra-high-and normal-strength transverse reinforcements", ACI Structural Journal,  (2001), 395-406 DOI:
15. Mirza, S.A. and Skrabek, B., "Statistical analysis of slender composite beam-column strength", Journal of Structural Engineering,  Vol. 118, No. 5, (1992), 1312-1332 DOI:
16. Mirza, S.A., Hyttinen, V. and Hyttinen, E., "Physical tests and analyses of composite steel-concrete beam-columns", Journal of Structural Engineering,  Vol. 122, No. 11, (1996), 1317-1326 DOI:
17. El-Tawil, S. and Deierlein, G.G., "Strength and ductility of concrete encased composite columns", Journal of Structural Engineering,  Vol. 125, No. 9, (1999), 1009-1019 DOI:
18. Munoz, P.R. and Hsu, C.-T.T., "Behavior of biaxially loaded concrete-encased composite columns", Journal of structural engineering,  Vol. 123, No. 9, (1997), 1163-1171 DOI:
19. Bogdan, T., Gerardy, J.C., Davies, D.W. and Popa, N., "Performance and capacity of composite “mega columns” with encased hot rolled steel sections", Euro Steel,  Vol. 1, No. 2-3, (2017), 1879-1888 DOI:
20. Lelkes, A. and Gramblička, Š., "Theoretical and experimental studies on composite steel–concrete columns", Procedia Engineering,  Vol. 65, (2013), 405-410 DOI:
21. Nematzadeh, M., Fazli, S. and Hajirasouliha, I., "Experimental study and calculation of laterally-prestressed confined concrete columns", Steel and Composite Structures,  Vol. 23, No. 5, (2017), 517-527 DOI:
22. ACI, "Standard practice for selecting proportions for normal, heavyweight, and mass concrete(aci 211.1-91), ACI manual of concrete practice,  (1996),  1-38.
23. ASTM, "E8/e8m-2013, standard test methods for tension testing of metallic materials, ASTM International, West Conshohocken, USA,  (2013).
24. Nematzadeh, M. and Ghadami, J., "Evaluation of interfacial shear stress in active steel tube-confined concrete columns", Computers and Concrete,  Vol. 20, No. 4, (2017), 469-481 DOI:
25. Haghinejada, A. and Nematzadeh, M., "Three-dimensional finite element analysis of compressive behavior of circular steel tube-confined concrete stub columns by new confinement relationships", Latin American Journal of Solids and Structures,  Vol. 13, No. 5, (2016), 916-944 DOI:
26. ACI, "Building code requirements for structural concrete (aci 318-11), Detroit, MI, USA,  (2011).
27. Barr, B. and Lee, M., "Modelling the strain-softening behaviour of plain concrete using a double-exponential model", Magazine of Concrete Research,  Vol. 55, No. 4, (2003), 343-353 DOI:
28.   Zhao, X.-L., Han, L.-H. and Lu, H., "Concrete-filled tubular members and connections, CRC Press,  (2010).