PSI - Issue 70

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

126

V-bracing and diagonal bracing exhibit least reduction, indicating they may be less successful in limiting lateral displacements. 6.2.2 Roof displacement The lateral displacement of unbraced frames and those with various bracing configurations for the load case, considering three-dimensional earthquake effects is shown in Table 1. Roof displacement results were compared across all brace configurations included in the study, with the unbraced frame serving as the baseline. X-braced designs lower side-to-side movements. The results show a significant reduction in roof displacement with bracing, with the unbraced frame experiencing the highest displacement of 288.153 mm. X-Braced and X-Intersecting Braced frames achieve the greatest reduction of around 72.77% when compared to the unbraced frame, followed by Chevron-Braced (69.7%), V-Braced (67.57%), and Diagonal-Braced (65.44%). X-type bracing proves the most effective in enhancing lateral stiffness, while diagonal bracing, though beneficial, provides the least reduction. Overall, bracing significantly improves structural stability, with X-Bracing emerging as the optimal choice for minimizing lateral displacement. These results completely align with the results of (Desai, 2010), who investigated the use of three similar brace types.

Table 1 : Roof displacement in frames Frame Configuration

Roof Displacement (mm)

Percentage Reduction

Unbraced X-Braced

288.153 78.507 78.478 87.302 93.460 99.578

-

72.76% 72.77% 69.70% 67.57% 65.44%

X int.-Braced

Chevron-Braced

V-Braced

Diagonal-Braced

6.2.3 Lateral stiffness Among all storey heights, an unbraced structure has the least amount of rigidity, which shows that the frame is far more pliable and susceptible to lateral stresses in the absence of bracing. X- braced and X-intersecting bracing provide the highest lateral stiffness across all storey heights, which indicates that these bracing configurations are the most effective in resisting lateral deformations. Chevron, V-braced, and diagonal-braced frames offer moderate stiffness improvements compared to an unbraced frame. Their effectiveness is lower than X- bracing configurations but still beneficial. It can be seen in figure 4 that there is sudden rise in stiffness when moving from the first-floor diaphragm to second-floor diaphragm and afterwards there is continuous fall in the stiffness values with rising height; this can be because of the reason that there is no rigid floor diaphragm assigned at the plinth level.

Unbraced

X-Braced

X Int.-Braced

Chevron-Braced

V-Braced

Diagonal-Braced

2.50E+06

2.00E+06

1.50E+06

1.00E+06

5.00E+05

Lateral Stifness (kN)

0.00E+00

3

6

9

12

15

18

21

24

27

30

Storey Height (m)

Fig. 4: Lateral Stiffness Variation