Seismic Fragility Analysis of a Three-story Cross-laminated Timber Building Considering Near and Far Field Ground Motions

This paper investigates the seismic response of the three-story Cross-Laminated Timber (CLT) building of the SOFIE project subjected to the Near-Field (NF) Far-Field (FF) ground motions according to FEMA P-695. The numerical models have been developed in connector, wall and full-scale building levels in OpenSees. Nonlinear zero-length springs have been utilised to model the behaviour of CLT connectors while considering Gap joints only to transfer compression forces between panels and the rigid foundation without the ability to carry tensile forces. The CLT panels have been modelled as moment-resisting frames by applying elastic beam elements with high stiffness. The panel-to-panel and panel-to-foundation friction has also been considered by modifying the initial stiffness of the CLT connector springs. The building was analysed using Incremental Dynamic Analysis (IDA), including 2450 time-history simulations, to assess its behaviour during ground motions. Significant Damage (SD) and Near-Collapse (NC) damage stated have been identified for the building based on EN12512 standard through Modal Push-over Analysis (MPA). Subsequently, the fragility curves have been developed for the CLT building under NF and FF ground motions. The IDA curves prove that the CLT building considered in this paper is more affected by Near-Field Pulse-like (NF-P) than by Near-Field No-Pulse (NF-NP) and FF ground motions. Moreover, the modelled building is significantly more affected by NF-P ground motions than by NF-NP and FF motions, with a higher probability of collapse under NF-P conditions.