Flexural Load-Bearing Capacity Evaluation of Steel-SFRC Composite Beams under Positive Moment by Finite Element Method and Theoretical Analysis
Xiaojun Liao1, Shenlu Jiao2, Zheshi Wang1, Jiyu Xie1, Zhiqing Chen1, Wei Chang3,*
1 Guangzhou Expressway Co., Ltd., Guangzhou, China
2 China Railway Fourth Bureau Group Second Engineering, Co., Ltd., Suzhou, China
3 School of Civil Engineering, Harbin Institute of Technology, Harbin, China
* Corresponding Author: Wei Chang. Email: 
Structural Durability & Health Monitoring https://doi.org/10.32604/sdhm.2026.085407
Received 12 May 2026; Accepted 24 June 2026; Published online 22 July 2026
Abstract
To reduce self-weight, accelerate construction, and lower costs of steel-concrete composite beams, steel fiber-reinforced concrete (SFRC) was combined with steel to develop a novel steel-SFRC composite beam system. To evaluate the ultimate flexural load-bearing capacity of steel-SFRC composite beams, a three-dimensional finite element model (FEM) was established. Compared with test results, the simulated failure modes agreed well with the experimental observations, and the predicted ultimate flexural capacities ranged from 89% to 97% of the test values, validating the accuracy and reliability of the FEM. In addition, the effects of SFRC slab thickness, SFRC slab width, SFRC compressive strength, steel beam yield strength, steel beam web thickness, and longitudinal reinforcement ratio in the SFRC slab on the ultimate flexural load-bearing capacity of steel-SFRC composite beams were analyzed. The results showed that the ultimate flexural capacity increased significantly with thicker SFRC slabs, wider slabs, higher steel beam tensile strength, thicker webs, and higher longitudinal reinforcement ratios. The capacity first rose and then dropped with increasing SFRC compressive strength. Based on the position of the neutral axis, theoretical calculation models for the ultimate flexural capacity were established by dividing into two cases: the plastic neutral axis located in the steel beam and in the SFRC slab. Comparisons with FEM results showed that the proposed theoretical formulas had high prediction accuracy, with a mean ratio of predicted to simulated values of 0.891, a standard deviation of 0.067, and a coefficient of variation of 0.075, which can be used for the flexural design of steel-SFRC composite beams under positive moment.
Keywords
Steel-SFRC composite beam; flexural load-bearing capacity; FEM; parametric analysis; theoretical method
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