Assessment of Repairability Index of Building Connections with Posttensioned Strands

Abstract

Recently developed steel self-centering moment-resisting frames (SC-MRFs) have been validated analytically and experimentally as having the potential to eliminate structural damage under a design basis earthquake and restore their original vertical position following a major earthquake. This study developed the repairability index of posttensioned self-centering frames for near-field earthquakes (RIPSCF-N). According to the 12 models of the studied building, which was a building that can be repaired, the maximum rotation in its connection after the earthquake did not exceed the rotation of the immediate occupancy performance. Based on this, the output data of incremental dynamic analysis (IDA) analyses were drawn according to the connection of relative rotation and spectral acceleration. According to the performance levels predicted in the literature for each acceleration level, the value of the connection opening is divided by the opening of the design basis earthquake (DBE) level. The resulting curve shows the repairability index according to spectral acceleration; if the index is less than 1, the repairability target is achieved. To evaluate the damage of angles, the angle failure probability of posttensioned self-centering frames for near-field earthquakes (AFPPSCF-N) was developed. This index equation is determined according to the fragility curve and the intensity of damage in each building. According to the RIPSCF-N, the nine-story buildings had lower repairability than the three-story buildings. According to result of the AFPPSCF-N, this indicates a higher percentage of angle damage in nine-story buildings than in three-story buildings at similar spectral accelerations.