PSI - Issue 70

Vivek Kumar C et al. / Procedia Structural Integrity 70 (2025) 97–104

100

4. Structural Modelling A G+15 multistoried structural steel building with X bracings at various locations was designed using ETABS 21 software with and without X bracing systems across different zones shown in table 1 and 2. A Special Moment Resisting Frame (SMRF) displayed a 25 m x 22.5 m G+15 building on Type 2 soil in seismic zone IV.

Table 2. Parameters considered for analysis

Parameters Soil Type

Specification

Parameters Floor Finish Live Load

Specification

Hard Soil (Type II) 45m (15 Story)

1.5KN/m 2 4.0KN/m 2

Height of the building Story to story Height

3.0 m

Grade of Concrete (fck) Grade of Structural Steel (fys) Grade of Reinforcing Steel (fyr)

M35

Span length

5m

Fe 350 Fe 500

Column Size used Thickness of Slab

ISMB500 125 mm

5. Results and Discussions 5.1. Storey Displacement

The analysis of maximum storey displacement for structures without bracing and with X-bracing shows distinct effectiveness patterns. For the unbraced structure, displacement increases with height. At Story 1, the unbraced system shows displacements of 2.511 mm in EQx and 4.62 mm in EQy. Displacement varies, with the center and corners having nearly identical values of 1.152 mm and 1.265 mm in EQy, while other locations exhibit a higher displacement in EQx at 2.012 mm. By Story 15, displacements reach 53.628 mm in EQx and 63.714 mm in EQy. The center displacement is 34.427 mm in EQx and 48.382 mm in EQy, with corners slightly higher. The X-braced system significantly reduces displacements at all storeys. At Story 1, it reduces displacement to 1.152 mm in EQx and 1.24 mm in EQy, with corner displacements slightly higher. By Story 15, the X-braced system results in displacements of 40.648 mm in EQx and 50.6 mm in EQy, much lower than the unbraced structure. Displacement values at the center, corners, and other locations are consistently lower in X-braced across all storeys. At Story 15, the center displacement is 34.427 mm in EQx and 46.159 mm in EQy, both reduced compared to the unbraced system in Table 3.

Table 3. Maximum Storey Displacement (in mm) in different positions of X bracing

Unbraced

X Bracings – Maximum Storey Displacement (mm)

Storey

Centre (EQx)

Centre (EQy)

Corners (EQx)

Corners (EQy)

Alternate (EQx)

Alternate (EQy)

EQx EQy

Base

0

0

0

0

0

0

0

0

Story1 2.511 4.62 1.152 1.24 1.152 1.265 Story2 7.373 10.016 3.476 3.299 3.475 3.165 Story3 12.927 15.441 6.264 5.989 6.262 5.576 Story4 18.52 20.854 9.229 9.16 9.227 8.403 8.127 Story5 23.886 26.219 12.247 12.682 12.244 11.559 15.388 11.582 Story6 28.906 31.494 15.25 16.443 15.247 14.96 18.781 15.383 Story7 33.522 36.629 18.193 20.343 18.189 18.532 22.114 19.358 Story8 37.702 41.563 21.034 24.293 21.03 22.205 25.337 23.5 Story9 41.421 46.229 23.732 28.217 23.727 25.912 28.415 27.627 Story10 44.662 50.55 26.24 32.048 26.236 29.597 31.287 31.796 Story11 47.41 54.44 28.513 35.731 28.508 33.207 33.91 35.798 Story12 49.66 57.806 30.501 39.223 30.496 36.697 36.212 39.784 Story13 51.415 60.546 32.159 42.499 32.155 40.035 38.144 43.491 Story14 52.707 62.551 33.46 45.551 33.456 43.197 39.628 47.214 Story15 53.628 63.714 34.427 48.382 34.423 46.159 40.648 50.6 2.012 5.169 8.541 11.96 0.853 2.616 5.079