Comparative seismic performance of steel EBF shear links frame designed to IS 18168:2023 using force-based and direct displacement method

Abstract

Abstract The recent introduction of IS 18168:2023 marks a significant advancement in the seismic design of steel structures in India by providing dedicated provisions for eccentrically braced frames (EBFs). While the code promotes link-controlled energy dissipation, its performance under different design philosophies, particularly in the nonlinear range, remains largely unexplored. This study presents a comprehensive seismic performance evaluation of steel EBF buildings designed as per IS 18168:2023 using conventional Force-Based Design (FBD) and Direct Displacement-Based Design (DDBD) approaches. The nonlinear static pushover analysis, nonlinear time-history analysis, and incremental dynamic analysis are performed for four building heights of 3-, 6-, 9-, and 12-storey. In addition, various important response parameters, including inter-storey drift, link rotation, plastic hinge distribution, variability, and collapse-related behaviour, have been systematically examined. Based on the results, it has been confirmed that EBF systems designed according to IS 18,168 exhibit a stable and desirable seismic behaviour, with inelastic deformation pretty much localized in the shear links. With respect to FBD, however, DDBD provides stronger control over nonlinear response due to approximately 20–40% lower median drift demands, 30–50% reduction at critical link rotation in MCE level, and strongly reduced record-to-record variability. Further, the drift escalation in DDBD frames is delayed while collapse robustness is notably improved, particularly for the midand high-rise buildings. Overall, the study brings out that though IS 18,168 provides a robust codal framework in the design of EBF systems, integrating DDBD within this codal context further leads to a more realistic, predictable, and performanceoriented seismic response, especially under strong ground motions.