PSI - Issue 70

Abhishek Badalia et al. / Procedia Structural Integrity 70 (2025) 121–128

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loads effectively through the frame, improve load transfer through axial mechanisms, making the RC structures more resistant to seismic loads. The past studies strongly recommend the use of X-type bracing for multi-story buildings requiring seismic retrofitting. Kulkarni et al. (2013) employed a numerical analysis approach to investigate the seismic response of reinforced concrete (RC) braced frames, focusing on various bracing configurations to enhance lateral stability. The study found that carefully selected bracing patterns could enhance seismic performance in RC frames while achieving significant cost savings, with bay-wise and level-wise configurations providing optimal solutions for structural economy and stability. The study also underscores the efficiency of strategically placed bracing patterns, particularly in taller RC frames, and demonstrates that a well-planned retrofitting strategy using steel bracings can both enhance seismic performance and minimize retrofitting costs. Boru and Aydin, (2022) investigated the effect of different steel brace types on reinforced concrete frame retrofitting and concluded that X-type and K-type bracings provide superior stiffness and strength compared to other configurations. Authors focused on selecting a suitable bracing section for a RC building under seismic loading. They analysed different bracing systems with various steel sections and found that K and X-bracing with a tubular steel section performed the best in terms of reducing displacement and increasing base shear capacity. Similarly, Poudel and Suwal, (2020) conducted a seismic performance analysis of RC frames using different steel bracing configurations and observed that steel bracing effectively reduces story displacement and drift. Among the tested configurations, X and inverted V-bracing showed the best results in reducing structural deformations. A comparative study by Ahiwale et al., (2023) evaluated the seismic response of an RC frame with various bracing systems using SAP 2000 software, including eight different bracing configurations. The results showed that X-type bracing led to the maximum reduction in lateral displacement. The study concluded that steel bracing is an effective retrofitting measure to enhance seismic resilience and emphasized the selection of an appropriate configuration based on building height, seismic zone, and structural requirements. The impact of steel bracing on key structural parameters, such as stiffness, inter-story drift, and base shear, has been extensively studied. Studies have indicated that the inclusion of steel bracing improves lateral stiffness and reduces drift significantly. A research study compared different bracing types and reported that X-bracing led to a reduction in story drift by up to 65% and an increase in base shear resistance. Another study by Tahamouli Roudsari et al., (2017) found that the use of eccentric, V braces enhances the ductility of RC frames while reducing the axial forces in columns; while X-braces are more from stiffness, strength and crack control perspective However, the choice of bracing configuration should be based on the height of the building, as different patterns may have varying effects on stiffness and energy dissipation. Various numerical studies using software like ETABS, SAP2000, and STAAD. Pro has validated the effectiveness of different bracing patterns. A study on Self-Centering Energy Dissipative (SCED) braces using pushover analysis also found that X-bracing is the most efficient in increasing the structural capacity and reducing displacement demands, providing balanced improvement in strength, stiffness, and ductility without causing force concentrations in structural members (Joseph et al., 2022). Use of Buckling Restrained Braces (BRB) has become popular in recent years, and researchers suggest that these bracing systems are more cost-effective to improve seismic performance. They intend to make brace buckling a viable energy dissipation mechanism where beams and columns in braced bays are intended to remain elastic (Shen et al., 2017). Overall, the literature review indicates that steel bracing is a viable and effective method for retrofitting RC frames to improve their seismic performance. 6. Parametric Study 6.1 Methodology A G+9 reinforced concrete Ordinary Moment Resisting Frame (OMRF) located in seismic zone IV as per IS:1893 (Part 1):2016 and founded on a medium soil, is considered in this study. The building was 24 m × 24 m in plan, having each bay of 4m. The storey height was 3m for each storey, totaling to 30m as marked in figure 1. The building is assumed to be designed for M30 concrete and Fe 500 steel. The beams are sized 450×500mm and columns are 600×600mm. The frame is first analyzed as OMRF later, braces were added in the end bays of the frame in each principal plan directions. The brace configurations included internal type X-brace, X-intersecting brace, Chevron brace, V-brace, forward and backward diagonal brace provided in the peripheral frame. Figure 2 shows the OMRF as