PSI - Issue 70

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

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well as different brace configurations adopted. The hollow steel section of 150×150×8mm was selected as brace member for retrofitting concerning guidelines of IS 15988: 2013. The structure was modeled, and appropriate properties and specifications were applied in STAAD Pro software. Seismic load was defined considering the site conditions and structural characteristics, and gravity loads were applied as per IS 875 provisions. Load combinations considering three-dimensional earthquake effects were applied as per clause 6.3.4.1 of IS:1893(Part 1):2016. Static and dynamic response spectrum analysis was performed, and the results were validated.

Fig. 1: Building Dimensions

Fig. 2: a) OMRF; b) X-Brace; c) X Int. Brace. d) Chevron Brace; e) V-Brace; f) Diagonal Brace

6.2 Discussion of Results The results of inter-story drift, roof displacement, lateral stiffness, seismic weight, base shear, frequency and period of oscillation in different modes of oscillation were studied and compared for different brace configurations with respect to the unbraced frame being considered as benchmark frame. Results are discussed in the form of a percentage increase or decrease in these performance parameters as beneficial for the overall performance point of view. 6.2.1 Inter-storey drift The inter-storey drift results of braced frames were compared with OMRF. Figure 3 presents the percentage reduction in drift for all adopted brace configurations. Both X-braced and X-intersecting braced observed around 61% less story drift compared to unbraced frame. There is a moderate reduction in the Chevron braced frame, about 59%. The layouts that show minimum reduction story drift are V-braced and diagonal braced, showing the worst performance. Because they can withstand both lateral forces and axial forces effectively, these results demonstrate that the X-bracing configurations (X-Braced and X Int.-Braced) are the most effective in decreasing drift. Chevron bracing is found less effective; this may be due to load transfer at the beam's midspan potentially causing a mechanism.

53% 54% 55% 56% 57% 58% 59% 60% 61% 62%

61%

61%

59%

57%

56%

Percentage Reduction in Drift

X-Braced X Int.-Braced Chevron-Braced V-Braced Diagonal-Braced

Bracing Configuration

Fig. 3: Inter-Storey Drift Reduction in Different Brace Configurations