The provisions of CSA O86 (2019) for Cross-laminated Timber (CLT) shear walls recommend the design of non-dissipative hold-downs with sufficient deformability to facilitate wall rocking. A hyperelastic hold-down system was proposed to satisfy these criteria. In this study, a numerical model was developed to capture the behaviour of CLT shear walls with the hyperelastic hold-down system using data from previous component level and full-scale shear testing. Six hold-down configurations were calibrated using the software OpenSees. Different modelling approaches were attempted; ultimately, a back calibration approach using the shear wall test data produced acceptable results. Calibration parameters were derived for the OpenSees ‘Hysteretic material’ for each hold-down configuration utilizing data from six tests on shear walls with un-coupled panels, and validated with the results from twelve additional tests on shear walls with coupled panels. The average differences between test and model for corner uplift, force at peak lateral displacement and energy dissipation were found to be 7%, 12% and 11%, respectively. A set of equations were proposed to predict calibration parameters of untested configurations. Finally, a two-storey platform-type shear wall was designed and modelled applying the calibrated Hysteretic material for the hyperelastic hold-downs. The developed model can be used to predict the shear wall performance of un-tested configurations.
A proposed hybrid lateral load resisting system combining a moderately ductile steel moment resisting frame (SMRF) with Cross-laminated Timber (CLT) balloon-framed shear walls is investigated on 8, 12 and 16-storey case-study buildings using equivalent static, linear dynamic (modal), nonlinear static (push-over) and nonlinear dynamic (time history) analyses. First, a SMRF is designed using ETABS, then the hybrid structures are analysed in OpenSees. By adding the CLT shear wall to steel moment frame, the period of structure decreased and its stiffness increased. The time history analyses result revealed that by adding the CLT shear wall the maximum drift decreased, while the maximum base shear in hybrid structure slightly increased. The hold down uplift forces under earthquake records are reported and compared to each other. Using push-over capacity-curves, a ductility reduction factor of 3.6, an over strength factor of 1.57 and a seismic response modification factor of 5.67 are derived.
