Comparison of seismic behavior between RC frame structures without and with diagonal steel reinforcement elements

This paper focuses on the numerical evaluation of the seismic behavior of a reinforced
concrete frame structure without diagonal steel reinforcement elements and five
strengthened variants using different steel profiles. Variants include steel diagonal
elements with different profiles (CHS 114.3×5, HEA 100, IPE 120, RHS 120×80×5 and
UNP 120, all steel grade S235). Comparison is made according to numerical
calculation results of structure loaded with seismic action. Paper focuses on
comparing lateral displacements and material efficiency of different steel diagonal
variants. Structural models are made in the SCIA Engineer 2026 software. Structure is
loaded with seismic load from two orthogonal horizontal directions according to
Eurocode 8 with return period of 95 years (serviceability limit state).
Reinforced concrete frame structure without diagonal steel reinforcement elements
demonstrated significant lateral displacements. By implementing steel diagonal
reinforcement elements, a notable reduction in structural lateral displacements was
achieved, reaching up to approximately 90%. The comparative analysis of different
diagonal steel reinforcement elements demonstrated that all strengthening variants
significantly improved the global stiffness and seismic resistance of the structure,
with the HEA 100 profile providing the most effective performance while consuming
highest steel quantity.
Numerical results of all analyzed variants confirm that diagonal steel reinforcement
elements represent an efficient and practical strengthening solution for existing
reinforced concrete frame structures in seismic regions.