Seismic performance of steel structures retrofitted with optimal slack cable collapse prevention system

The present paper provides a performance-based evaluation of the configuration of the slack cable collapse prevention system for seismic retrofitting of existing buildings. In order to avert collapse during strong ground motions, the studied structures are strengthened with pairs of slack cables that work in tandem with the moment frame system involving the gravity framing. The effect of different cable placements, diameters, and slacking gaps in 4-, 8- and 12-story archetypical steel frame buildings are examined. Here, 2620 Pushover and 6 Incremental Dynamic Analysis (IDA) with 22 earthquakes are conducted for selected cases. In the first phase, the feasible and optimum configurations are determined, and in the second phase, their performances are captured through fragility assessment. The investigations indicated that the slack cable system, utilizing a cost-effective mechanism, improves the performance of the buildings and substantially reduces the probability of collapse during Maximum Considered Earthquake (MCE) ground motions. Particularly in 8 and 12 story structures, It is observed that the placements become optimal when they are installed in central and lower than structures' half height.