Seismic Fragility Estimates for Cross-Laminated Timber Platform Building

AbstractCross-laminated timber (CLT) has been gaining popularity also in seismic regions, because of its low carbon footprint and potential cost-competitiveness with concrete and steel construction. Recent effort has focused on developing standardized design provisions for CLT buildings. In the study presented herein, incremental dynamic analysis (IDA) was performed on a six-story CLT platform-type building. A nonlinear numerical model was developed in OpenSees considering the CLT shear walls as elastic shell elements and the connections (wall-to-foundation, wall-to-floor, and wall-to-wall) as nonlinear springs. The hysteresis behavior of the connections was modeled using “pinching4” after calibrating its parameters against experimental results, and the load-deformation response of the shear walls was validated against full-scale test results. The building’s seismic performance—terms of interstory drift until collapse—was evaluated using fragility curves constructed from the IDA. The probability of collapse was less than 0.1% at the maximum considered earthquake, and the resulting collapse margin ratio demonstrated that a six-story CLT platform-type building can safely be built in a high seismic zone if appropriately designed.